' xi—
Shawn M. Garvin, Regional Administrator
U.S. Environmental Protection Agency
Region 3
Judith A. Enck, Regional Administrator
U.S. Environmental Protection Agency
Region 2
DATE
/ /
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Chesapeake Bay Total Maximum Daily Load
for Nitrogen, Phosphorus and Sediment
December 29, 2010
U.S. Environmental Protection Agency
Region 3
Water Protection Division
Air Protection Division
Office of Regional Counsel
Philadelphia, Pennsylvania
U.S. Environmental Protection Agency
Region 3
Chesapeake Bay Program Office
Annapolis, Maryland
and
U.S. Environmental Protection Agency
Region 2
Division of Environmental Planning and Protection
New York, New York
in coordination with
U.S. Environmental Protection Agency
Office of Water
Office of Air and Radiation
Office of General Counsel
Office of the Administrator
Washington, D.C.
and in collaboration with
Delaware, the District of Columbia, Maryland, New York,
Pennsylvania, Virginia, and West Virginia
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Chesapeake Bay TMOL
CHESAPEAKE BAY TMDL EXECUTIVE SUMMARY
INTRODUCTION
The U.S. Environmental Protection Agency (EPA) has established the Chesapeake Bay Total
Maximum Daily Load (TMDL), a historic and comprehensive "pollution diet" with rigorous
accountability measures to initiate sweeping actions to restore clean water in the Chesapeake
Bay and the region's streams, creeks and rivers.
Despite extensive restoration efforts during the past 25 years, the TMDL was prompted by
insufficient progress and continued poor water quality in the Chesapeake Bay and its tidal
tributaries. The TMDL is required under the federal Clean Water Act and responds to consent
decrees in Virginia and the District of Columbia from the late 1990s. It is also a keystone
commitment of a federal strategy to meet President Barack Obama's Executive Order to restore
and protect the Bay.
The TMDL - the largest ever developed by EPA - identifies the necessary pollution reductions
of nitrogen, phosphorus and sediment across Delaware. Maryland. New York, Pennsylvania,
Virginia, West Virginia and the District of Columbia and sets pollution limits necessary to meet
applicable water quality standards in the Bay and its tidal rivers and embayments. Specifically,
the TMDL sets Bay watershed limits of 185.9 million pounds of nitrogen, 12.5 million pounds of
phosphorus and 6.45 billion pounds of sediment per year - a 25 percent reduction in nitrogen,
24 percent reduction in phosphorus and 20 percent reduction in sediment. These pollution limits
are further divided by jurisdiction and major river basin based on state-of-the-art modeling tools,
extensive monitoring data, peer-reviewed science and close interaction with jurisdiction partners.
The TMDL is designed to ensure that all pollution control measures needed to fully restore the
Bay and its tidal rivers are in place by 2025, with at least 60 percent of the actions completed by
2017. The TMDL is supported by rigorous accountability measures to ensure cleanup
commitments are met, including short-and long-term benchmarks, a tracking and accountability
system for jurisdiction activities, and federal contingency actions that can be employed if
necessary to spur progress.
Watershed Implementation Plans (WIPs), which detail how and when the six Bay states and the
District of Columbia will meet pollution allocations, played a central role in shaping the TMDL.
Most of the draft WIPs submitted by the jurisdictions in September 2010 did not sufficiently
identify programs needed to reduce pollution or provide assurance the programs could be
implemented. As a result, the draft TMDL issued September 24, 2010 contained moderate- to
high-level backstop measures to tighten controls on federally permitted point sources of
pollution.
A 45-day public comment period on the draft TMDL was held from September 24 to November
8. 2010. During that time, EPA held 18 public meetings in all seven Bay watershed jurisdictions,
which were attended by about 2.500 citizens. EPA received more than 14,000 public comments
and, where appropriate, incorporated responses to those comments in developing the final
TMDL.
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Chesapeake BayTMDL
After states submitted the draft WIPs, EPA worked closely with each jurisdiction to revise and
strengthen its plan. Because of this cooperative work and state leadership, the final WIPs were
significantly improved. Examples of specific improvements include:
• Regulated point sources and non-regulated nonpoint sources of nitrogen, phosphorus, and
sediment are fully considered and evaluated separately in terms of their relative
contributions to water quality impairment of the Chesapeake Bay's tidal waters.
• Committing to more stringent nitrogen and phosphorus limits at wastewater treatment
plants, including on the James River in Virginia. (Virginia. New York, Delaware)
• Pursuing state legislation to fund wastewater treatment plant upgrades, urban stormwatcr
management and agricultural programs. (Maryland, Virginia, West Virginia)
• Implementing a progressive stormwater permit to reduce pollution. (District of Columbia)
• Dramatically increasing enforcement and compliance of state requirements for agriculture.
(Pennsylvania)
• Committing state funding to develop and implement state-of-the-art-technologies for
converting animal manure to energy for farms. (Pennsylvania)
• Considering implementation of mandatory programs for agriculture by 2013 if pollution
reductions fall behind schedule. (Delaware, Maryland, Virginia)
These improvements enabled EPA to reduce and remove most federal backstops, leaving a few
targeted backstops and a plan for enhanced oversight and contingency actions to ensure progress.
As a result, the final TMDL is shaped in large part by the jurisdictions' plans to reduce pollution,
which was a long-standing priority for EPA and why the agency always provided the
jurisdictions with flexibility to determine how to reduce pollution in the most efficient, cost-
effective and acceptable manner.
Now the focus shifts to the jurisdictions' implementation of the WIP policies and programs that
will reduce pollution on-the-ground and in-the-water. EPA will conduct oversight of WIP
implementation and jurisdictions' progress toward meeting two-year milestones. If progress is
insufficient, EPA is committed to take appropriate contingency actions including targeted
compliance and enforcement activities, expansion of requirements to obtain NPDES permit
coverage for currently unregulated sources, revision of the TMDL allocations and additional
controls on federally permitted sources of pollution, such as wastewater treatment plants, large
animal agriculture operations and municipal stormwater systems.
In 2011, while the jurisdictions continue to implement their WIPs, they will begin development
of Phase II WIPs, designed to engage local governments, watershed organizations, conservation
districts, citizens and other key stakeholders in reducing water pollution.
TMDL BACKGROUND
The Clean Water Act (CWA) sets an overarching environmental goal that all waters of the
United States be "fishable" and "swimmable.'1 More specifically it requires states and the District
of Columbia to establish appropriate uses for their waters and adopt water quality standards that
are protective of those uses. The CWA also requires that every two years jurisdictions develop -
with EPA approval - a list of waterways that are impaired by pollutants and do not meet water
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Chesapeake BayTMDL
quality standards. For those waterways identified on the impaired list, a TMDL must be
developed. A TMDL is essentially a "pollution diet" that identifies the maximum amount of a
pollutant the waterway can receive and still meet water quality standards.
Most of the Chesapeake Bay and its tidal waters are listed as impaired because of excess
nitrogen, phosphorus and sediment. These pollutants cause algae blooms that consume oxygen
and create "dead zones" where fish and shellfish cannot survive, block sunlight that is needed for
underwater Bay grasses, and smother aquatic life on the bottom. The high levels of nitrogen,
phosphorus and sediment enter the water from agricultural operations, urban and suburban
stormwater runoff, wastewater facilities, air pollution and other sources, including onsite septic
systems. Despite some reductions in pollution during the past 25 years of restoration due to
efforts by federal, state and local governments; non-governmental organizations; and
stakeholders in the agriculture, urban/suburban stormwater, and wastewater sectors, there has
been insufficient progress toward meeting the water quality goals for the Chesapeake Bay and its
tidal waters.
More than 40,000 TMDLs have been completed across the United States, but the Chesapeake
Bay TMDL will be the largest and most complex thus far - it is designed to achieve significant
reductions in nitrogen, phosphorus and sediment pollution throughout a 64,000-square-mile
watershed that includes the District of Columbia and large sections of six states. The TMDL is
actually a combination of 92 smaller TMDLs for individual Chesapeake Bay tidal segments and
includes pollution limits that are sufficient to meet state water quality standards for dissolved
oxygen, water clarity, underwater Bay grasses and chlorophyll-a, an indicator of algae levels
(Figure ES-1). It is important to note that the pollution controls employed to meet the TMDL
will also have significant benefits for water quality in tens of thousands of streams, creeks, lakes
and rivers throughout the region.
Since 2000, the seven jurisdictions in the Chesapeake Bay watershed (Delaware, District of
Columbia, Maryland, New York, Pennsylvania, Virginia, and West Virginia), EPA and the
Chesapeake Bay Commission, which are partners in the Chesapeake Bay Program, have been
planning for a Chesapeake Bay TMDL.
Since September 2005, the seven jurisdictions have been actively involved in decision-making to
develop the TMDL. During the October 2007 meeting of the Chesapeake Bay Program's
Principals' Staff Committee, the Bay watershed jurisdictions and EPA agreed that EPA would
establish the multi-state TMDL. Since 2008, EPA has sent official letters to the jurisdictions
detailing all facets of the TMDL, including: nitrogen, phosphorus and sediment allocations;
schedules for developing the TMDL and pollution reduction plans; EPA's expectations and
evaluation criteria for jurisdiction plans to meet the TMDL pollution limits; reasonable assurance
for controlling nonpoint source pollution; and backstop actions that EPA could take to ensure
progress.
The TMDL also resolves commitments made in a number of consent decrees, Memos of
Understanding, the Chesapeake Bay Foundation settlement agreement of 2010, and settlement
agreements dating back to the late 1990s that address certain tidal waters identified as impaired
in the District of Columbia, Delaware, Maryland and Virginia.
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Chesapeake Bay TMDL
Figure ES-1. A nitrogen, phosphorus and sediment TMDL has been developed for each of the 92
Chesapeake Bay segment watersheds.
Additionally, President Obama issued Executive Order 13508 on May 12, 2009, which directed
the federal government to lead a renewed effort to restore and protect the Chesapeake Bay and its
watershed. The Chesapeake Bay TMDL is a keystone commitment in the strategy developed by
11 federal agencies to meet the President's Executive Order.
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December 29, 2010
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Chesapeake Bay TMDL
DEVELOPING THE CHESAPEAKE BAY TMDL
Development of the Chesapeake Bay TMDL required extensive knowledge of the stream flow
characteristics of the watershed, sources of pollution, distribution and acreage of the various land
uses, appropriate best management practices, the transport and fate of pollutants, precipitation
data and many other factors. The TMDL is informed by a series of models, calibrated to decades
of water quality and other data, and refined based on input from dozens of Chesapeake Bay
scientists. Modeling is an approach that uses observed and simulated data to replicate what is
occurring in the environment to make future predictions, and was a critical and valuable tool to
develop the Chesapeake Bay TMDL.
The development of the TMDL consisted of several steps:
I. LPA provided the jurisdictions with loading allocations for nitrogen, phosphorus and
sediment for the major river basins by jurisdiction.
2. Jurisdictions developed draft Phase I WIPs to achieve those basin-jurisdiction allocations.
In those draft WIPs, jurisdictions made decisions on how to further sub-allocate the
basin-jurisdiction loadings to various individual point sources and a number of point and
nonpoint source pollution sectors.
3. LPA evaluated the draft WIPs and, where deficiencies existed, HPA provided backstop
allocations in the draft TMDL that consisted of a hybrid of the jurisdiction WIP
allocations modified by 1:PA allocations for some source sectors to fill gaps in the WIPs.
4. The draft TMDL was published for a 45-day public comment period and EPA held 18
public meetings in all six states and the District of Columbia. Public comments were
received, reviewed and considered for the final TMDL.
5. Jurisdictions, working closely with EPA, revised and strengthened Phase I WIPs and
submitted final versions to EPA.
6. LPA evaluated the final WIPs and used them along with public comments to develop the
final TMDL.
Since nitrogen and phosphorus loadings from all parts of the Bay watershed have an impact on
the impaired tidal segments of the Bay and its rivers, it was necessary for EPA to allocate the
nitrogen and phosphorus loadings in an equitable manner to the states and basins. EPA used
three basic guides to divide these loads.
• Allocated loads should protect living resources of the Bay and its tidal tributaries and
should result in all segments of the Bay mainstem, tidal tributaries and embayments
meeting water quality standards for dissolved oxygen, chlorophyll «, water clarity and
underwater Bay grasses.
• Tributary basins that contribute the most to the Bay water quality problems must do the
most to resolve those problems (on a pound-per-pound basis) (Figure ES-2).
• All tracked and reported reductions in nitrogen, phosphorus and sediment loads are credited
toward achieving final assigned loads.
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Chesapeake Bay TMDL
Effectiveness
Nitrogen
H 00-12
• 1.3-2.7
28-42
43-5.5
B 58-7.1
• 72-103
Figure ES-2. Sub-basins across the Chesapeake Bay watershed with the
highest (red) to lowest (blue) pound for pound nitrogen pollutant loading
effect on Chesapeake Bay water quality.
In addition, EPA has committed to reducing air deposition of nitrogen to the tidal waters of the
Chesapeake Bay from 17.9 to 15.7 million pounds per year. The reductions will be achieved
through implementation of federal air regulations during the coming years.
To ensure that these pollutant loadings will attain and maintain applicable water quality
standards, the TMDL calculations were developed to account for critical environmental
conditions a waterway would face and seasonal variation. An implicit margin of safety for
nitrogen and phosphorus, and an explicit margin of safety for sediment, also are included in the
TMDL.
Ultimately, the TMDL is designed to ensure that by 2025 all practices necessary to fully restore
the Bay and its tidal waters are in place, with at least 60 percent of the actions taken by 2017.
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December 29, 2010
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Chesapeake Bay TMDL
The TMDL loadings to the basin-jurisdictions are provided in Table ES-1. These loadings were
determined using the best peer-reviewed science and through extensive collaboration with the
jurisdictions and are informed by the jurisdictions' Phase I WIPs.
Table ES-1. Chesapeake Bay TMDL watershed nitrogen, phosphorus and sediment final
allocations by jurisdiction and by major river basin.
Jurisdiction
Pennsylvania
Maryland
Virginia
District of
Columbia
New York
Delaware
West Virginia
Basin
Susquehanna
Potomac
Eastern Shore
Western Shore
PA Total
Susquehanna
Eastern Shore
Western Shore
Patuxent
Potomac
MD Total
Eastern Shore
Potomac
Rappahannock
York
James
VA Total
Potomac
DC Total
Susquehanna
NY Total
Eastern Shore
DE Total
Potomac
James
WV Total
Total Basin/Jurisdiction Draft
Allocation
Atmospheric Deposition Draft
Allocationa
Total Basinwide Draft
Allocation
Nitrogen
allocations
(million Ibs/year)
68.90
4.72
0.28
0.02
73.93
1.09
9.71
9.04
2.86
16.38
39.09
1.31
17.77
5.84
5.41
23.09
53.42
2.32
2.32
8.77
8.77
2.95
2.95
5.43
0.02
5.45
185.93
15.7
201.63
Phosphorus
allocations
(million Ibs/year)
2.49
0.42
0.01
0.00
2.93
0.05
1.02
0.51
0.24
0.90
2.72
0.14
1.41
0.90
0.54
2.37
5.36
0.12
0.12
0.57
0.57
0.26
0.26
0.58
0.01
0.59
12.54
N/A
12.54
Sediment
allocations
(million Ibs/year)
1,741.17
221.11
21.14
0.37
1,983.78
62.84
168.85
199.82
106.30
680.29
1,218.10
11.31
829.53
700.04
117.80
920.23
2,578.90
11.16
11.16
292.96
292.96
57.82
57.82
294.24
16.65
310.88
6,453.61
N/A
6,453.61
a Cap on atmospheric deposition loads direct to Chesapeake Bay and tidal tributary surface waters to be achieved
by federal air regulations through 2020.
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Chesapeake Bay TMDL
ACCOUNTABILITY AND GOALS
The Chesapeake Bay TMDL is unique because of the extensive measures EPA and the
jurisdictions have adopted to ensure accountability for reducing pollution and meeting deadlines
for progress. The TMDL will be implemented using an accountability framework that includes
WIPs, two-year milestones, EPA's tracking and assessment of restoration progress and, as
necessary, specific federal contingency actions if the jurisdictions do not meet their
commitments. This accountability framework is being established in part to provide
demonstration of the reasonable assurance provisions of the Chesapeake Bay TMDL pursuant to
both the Clean Water Act (CWA) and the Chesapeake Bay Executive Order, but is not part of the
TMDL itself.
When EPA establishes or approves a TMDL that allocates pollutant loads to both point and
nonpoint sources, it determines whether there is a "reasonable assurance" that the point and
nonpoint source loadings will be achieved and applicable water quality standards will be attained.
Reasonable assurance for the Chesapeake Bay TMDL is provided by the numerous federal, state
and local regulatory and non-regulatory programs identified in the accountability framework that
EPA believes will result in the necessary point and nonpoint source controls and pollutant
reduction programs. The most prominent program is the CWA's National Pollutant Discharge
Elimination System (NPDES) permit program that regulates point sources throughout the nation.
Many nonpoint sources are not covered by a similar federal permit program; as a result, financial
incentives, other voluntary programs and state-specific regulatory programs are used to achieve
nonpoint source reductions. These federal tools are supplemented by a variety of state and local
regulatory and voluntary programs and other commitments of the federal government set forth in
the Executive Order strategy and identified in the accountability framework.
Beginning in 2012, jurisdictions (including the federal government) are expected to follow two-
year milestones to track progress toward reaching the TMDL's goals. In addition, the milestones
will demonstrate the effectiveness of the jurisdictions' WIPs by identifying specific near-term
pollutant reduction controls and a schedule for implementation (see next section for further
description of WIPs). EPA will review these two-year milestones and evaluate whether they are
sufficient to achieve necessary pollution reductions and, through the use of a Bay TMDL
Tracking and Accountability System, determine if milestones are met.
If a jurisdiction's plans are inadequate or its progress is insufficient, EPA is committed to take
the appropriate contingency actions to ensure pollution reductions. These include expanding
coverage of NPDES permits to sources that are currently unregulated, increasing oversight of
state-issued NPDES permits, requiring additional pollution reductions from point sources such as
wastewater treatment plants, increasing federal enforcement and compliance in the watershed,
prohibiting new or expanded pollution discharges, redirecting EPA grants, and revising water
quality standards to better protect local and downstream waters.
Watershed Implementation Plans
The cornerstone of the accountability framework is the jurisdictions' development of WIPs,
which serve as roadmaps for how and when a jurisdiction plans to meet its pollutant allocations
under the TMDL. In their Phase I WIPs, the jurisdictions were expected to subdivide the Bay
TMDL allocations among pollutant sources; evaluate their current legal, regulatory.
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Chesapeake Bay TMDL
programmatic and financial tools available to implement the allocations; identity and rectify
potential shortfalls in attaining the allocations; describe mechanisms to track and report
implementation activities; provide alternative approaches; and outline a schedule for
implementation.
EPA provided the jurisdictions with detailed expectations for WIPs in November 2009 and
evaluation criteria in April 2010. To assist with WIP preparation, EPA provided considerable
technical and financial assistance. EPA worked with the jurisdictions to evaluate various "what
if scenarios - combinations of practices and programs that could achieve their pollution
allocations.
The two most important criteria for a WIP is that it achieves the basin-jurisdiction pollution
allocations and meets EPA's expectations for providing reasonable assurance that reductions will
be achieved and maintained, particularly for non-permitted sources like runoff from agricultural
lands and currently unregulated stonnwater from urban and suburban lands.
After the draft Phase I WIP submittals in September 2010, a team of EPA sector experts
conducted an intense evaluation process, comparing the submissions with EPA expectations. The
EPA evaluation concluded that the pollution controls identified in two of the seven jurisdictions'
draft WIPs could meet nitrogen and phosphorus allocations and five of the seven jurisdictions'
draft WIPs could meet sediment allocations. Hie EPA evaluation also concluded that none of the
seven draft Phase I WIPs provided sufficient reasonable assurance that pollution controls
identified could actually be implemented to achieve the nitrogen, phosphorus and sediment
reduction targets by 2017 or 2025.
In response to its findings, EPA developed a draft TMDL that established allocations based on
using the adequate portions of the jurisdictions' draft WIP allocations along with varying degrees
of federal backstop allocations in all seven jurisdictions. Backstop allocations focused on areas
where EPA has the federal authority to control pollution allocations through NPDES permits,
including wastewater treatment plants, stormwater permits, and animal feeding operations.
Public Participation
The draft Chesapeake Bay TMDL was developed through a highly transparent and engaging
process during the past two years. The outreach effort included hundreds of meetings with
interested groups; two rounds of public meetings, stakeholder sessions and media interviews in
all six states and the District of Columbia in fall of 2009 and 2010; a dedicated EPA website; a
series of monthly interactive webinars; notices published in the Federal Register; and a close
working relationship with Chesapeake Bay Program committees representing citizens, local
governments and the scientific community.
The release of the draft Chesapeake Bay TMDL on September 24, 2010 began a 45-day public
comment period that concluded on November 8, 2010. During the comment period EPA
conducted 18 public meetings in all six states and the District of Columbia. More than 2,500
people participated in the public meetings. Seven of these meetings were also broadcast live
online. During the six weeks that EPA officials traveled around the watershed, they also held
do/ens of meetings with stakeholders, including local governments, agriculture groups.
homebuilder and developer associations, wastewater industry representatives and environmental
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Chesapeake Bay TMDL
organizations. EPA received more than 14,000 comments - most of which supported the TMDL
- and the Agency's response to those comments is included as an appendix to the TMDL.
Final Watershed Implementation Plans and TMDL
Since submittal of the draft WIPs and release of the draft TMDL in September 2010. EPA
worked closely with each jurisdiction to revise and strengthen its plan. Because of this
cooperative work and state leadership, the final WIPs were significantly improved. Examples of
specific improvements include:
• Committing to more stringent nitrogen and phosphorus limits at wastewater treatment
plants, including on the James River in Virginia. (Virginia, New York, Delaware)
• Pursuing state legislation to fund wastewater treatment plant upgrades, urban stormwater
management and agricultural programs. (Maryland, Virginia, West Virginia)
• Implementing a progressive stormwater permit to reduce pollution. (District of Columbia)
• Dramatically increasing enforcement and compliance of state requirements for agriculture.
(Pennsylvania)
• Committing state funding to develop and implement state-of-the-art-technologies for
converting animal manure to energy for farms. (Pennsylvania)
• Considering implementation of mandatory programs for agriculture by 2013 if pollution
reductions fall behind schedule. (Delaware, Maryland, Virginia)
These improvements enabled EPA to reduce and remove most federal backstops, leaving a few
targeted backstops and a plan for enhanced oversight and contingency actions to ensure progress.
Backstop Allocations, Adjustments, and Actions
Despite the significant improvement in the final WIPs, one of the jurisdictions did not meet all of
its target allocations and two of the jurisdictions did not fully meet EPA's expectations for
reasonable assurance for specific pollution sectors. To address these few remaining issues, EPA
included in the final TMDL several targeted backstop allocations, adjustments and actions. As a
result of the jurisdictions' significant improvements combined with EPA's backstops, EPA
believes the jurisdictions are in a position to implement their WIPs and achieve the needed
pollution reductions. This approach endorses jurisdictions' pollution reduction commitments,
gives them the flexibility to do it their way first, and signals EPA's commitment to fully use its
authorities as necessary to reduce pollution.
New York Wastewater - Backstop Allocation
• EPA closed the numeric gap between New York's WIP and its modified allocations by
establishing a backstop that further reduces New York's wasteload allocation for
wastewater. EPA is establishing an aggregate wasteload allocation for wastewater
treatment plants.
• EPA calculated this backstop WLA using the nitrogen and phosphorus performance levels
that New York committed to, but assumes that significant wastewater treatment plants
(WWTPs) are at current flow rather than design flow.
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Chesapeake Bay TMDL
• EPA understands that New York plans to renew and/or modify WWTP permits upon
completion of its Phase II WIP. consistent with the applicable TMDL allocations at that
time. New York is reviewing engineering reports from WWTPs and, in its Phase II WIP,
will provide information to support individual WLAs for these plants.
Pennsylvania Urban Stormwater- Backstop Adjustment
• EPA transferred 50 percent of the stormwater load that is not currently subject to NPDHS
permits from the load allocation to the wasteload allocation. The TMDL allocation
adjustment increases reasonable assurance that pollution allocations from urban stormwater
discharges will be achieved and maintained by signaling that EPA is prepared to designate
any of these discharges as requiring NPDES permits. Urban areas would only be subject to
NPDLS permit conditions protective of water quality as issued by Pennsylvania upon
designation. EPA will consider this step if Pennsylvania does not demonstrate progress
toward reductions in urban loads identified in the WIP. EPA may also pursue designation
activities based on considerations other than TMDL and WIP implementation.
• EPA will maintain close oversight of general permits for the Pennsylvania stormwater
sector (PAG-13 and PA(j-2) and may object if permits are not protective of water quality
standards and regulations. Upon review of Pennsylvania's Phase II WIP, EPA will revisit
the wasteload allocations for wastewater treatment plants, including more stringent
phosphorus limits, in the event that Pennsylvania does not reissue PAG-13 and PAG-2
general permits for Phase II MS4s and construction that are protective of water quality by
achieving the load reductions called for in Pennsylvania's Phase I WIP.
West Virginia Agriculture - Backstop Adjustment
• EPA shifted 75 percent of West Virginia's animal feeding operation (AFO) load into the
wasteload allocation and assumed full implementation of barnyard runoff control, waste
management and mortality composting practices required under a CAFO permit on these
AFOs. The shift signals that any of these operations could potentially be subject to state or
federal permits as necessary to protect water quality. AFOs would only be subject to
NPDES permit conditions as issued by West Virginia upon designation. EPA will consider
this step if West Virginia does not achieve reductions in agricultural loads as identified in
the WIP. EPA may also pursue designation activities based upon considerations other than
TMDL and WIP implementation.
• Based upon West Virginia's ability to demonstrate near-term progress implementing the
agricultural section of its WIP, including CAFO Program authorization and permit
applications and issuance, EPA will assess in the Phase II WIP whether additional federal
actions, such as establishing more stringent wasteload allocations for wastewater treatment
plants, are necessary to ensure that TMDL allocations are achieved.
Enhanced Oversight and Contingencies
While final WIPs were significantly improved and the jurisdictions deserve credit for the efforts,
EPA also has minor concerns with the assurance that pollution reductions can be achieved in
certain pollution sectors in Pennsylvania, Virginia and West Virginia. EPA has informed these
jurisdictions that it will consider future backstops if specific near-term progress is not
demonstrated in the Phase II WIP.
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Pennsylvania Agriculture
• Based on Pennsylvania's ability to demonstrate near-term progress implementing the
agricultural section of its WIP, including EPA approval for its CAFO program and
enhanced compliance assurance with state regulatory programs, EPA will assess in the
Phase II WIP whether additional federal actions, such as shifting AFO loads from the load
allocation to the wasteload allocation or establishing more stringent wasteload allocations
for WWTPs, are necessary to ensure that TMDL allocations are achieved.
Pennsylvania Wastewater
• EPA established individual wasteload allocations for wastewater treatment plants in the
TMDL to ensure that sufficient detail is provided to inform individual permits for sources
within the wasteload allocation. Individual allocations do not commit wastewater plants to
greater reductions than what the state has proposed in its WIP. Provisions of the TMDL
allow, under certain circumstances, for modifications of allocations within a basin to
support offsets and trading opportunities.
• EPA will assess Pennsylvania's near-term urban stormwater and agriculture program
progress and determine whether EPA should modify TMDL allocations to assume
additional reductions from wastewater treatment plants.
Virginia Urban Stormwater
• If the statewide rule and/or the Phase II WIP do not provide additional assurance regarding
how stormwater discharges outside of MS4 jurisdictions will achieve nitrogen, phosphorus,
and sediment reductipns proposed in the final Phase I WIP and assumed within the TMDL
allocations, EPA may shift a greater portion of Virginia's urban stormwater load from the
load allocation to the wasteload allocation. This shift would signal that substantially more
stormwater could potentially be subject to NPDES permits issued by the Commonwealth as
necessary to protect water quality.
West Virginia Urban Stormwater
• If stormwater rules and/or the Phase II WIP do not provide additional assurance regarding
how urban stormwater discharges outside of MS4 jurisdictions will achieve nitrogen,
phosphorus, and sediment allocations proposed in the final Phase I WIP and assumed within
the TMDL load allocations, EPA may shift a greater portion of West Virginia's urban
stormwater load from the load allocation to the wasteload allocation. The shift would signal
that substantially more urban stormwater could potentially be subject to state permit coverage
and/or federal Clean Water Act permit coverage as necessary to protect water quality.
West Virginia Wastewater
• EPA established individual wasteload allocations for significant wastewater treatment
plants in the TMDL to ensure that sufficient detail is provided to inform individual permits
for sources within the wastewater wasteload allocation. Individual allocations do not
commit wastewater plants to greater reductions than what the state has proposed in its WIP.
Provisions of this TMDL allow, under certain circumstances, for modifications of
allocations within a basin to support offsets and trading opportunities.
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• EPA will assess West Virginia's near-term agriculture program progress and determine
whether additional federal actions consistent with BPA's December 29, 2009 letter, such as
modifying TMDL allocations to assume additional reductions from wastewater treatment
plants, are necessary to ensure that TMDL allocations are achieved.
Ongoing oversight of Chesapeake Bay jurisdictions
FPA will carefully review programs and permits in all jurisdictions. EPA's goal is for
jurisdictions to successfully implement their WIPs, but EPA is prepared to take necessary actions
in all jurisdictions for insufficient WIP implementation or pollution reductions. Federal actions
can be taken at any time, although EPA will engage particularly during two-year milestones and
refining the TMDL in 2012 and 2017. Actions include:
• Expanding coverage of NPDES permits to sources that are currently unregulated
• Increasing oversight of state-issued NPDES permits
• Requiring additional pollution reductions from federally regulated sources
• Increasing federal enforcement and compliance
• Prohibiting new or expanded pollution discharges
• Conditioning or redirecting EPA grants
• Revising water quality standards to better protect local and downstream waters
• Discounting nutrient and sediment reduction progress if jurisdiction cannot verity proper
installation and management of controls
FINAL TMDL
As a result of the significantly improved WIPs and the removal and reduction of federal
backstops, the final TMDL is shaped in large part by the jurisdictions' plans to reduce pollution.
Jurisdiction-based solutions for reducing pollution was a long-standing priority for EPA and why
the agency always provided the jurisdictions with flexibility to determine how to reduce
pollution in the most efficient, cost-effective and acceptable manner.
Now, the focus shifts to jurisdictions' implementation of the WIP policies and programs
designed to reduce pollution on-the-ground and in-the-water. EPA will conduct oversight of WIP
implementation and jurisdictions' progress toward meeting two-year milestones. If progress is
insufficient, EPA will utilize contingencies to place additional controls on federally permitted
sources of pollution, such as wastewater treatment plants, large animal agriculture operations and
municipal stormwater systems, as well as target compliance and enforcement activities.
Federal agencies will greatly contribute to restoration of the Chesapeake Bay watershed,
particularly through implementation of the new federal strategy created under President Obama's
Executive Order. Eleven federal agencies have committed to a comprehensive suite of actions
and pursuit of critical environmental goals on the same 2025 timeline as the TMDL.
Additionally, federal agencies will be establishing and meeting two-year milestones, with the
specific charge of taking actions that directly support the jurisdictions in reducing pollution and
restoring water quality.
ES-13 December 29, 2010
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Chesapeake Bay TMDL
The jurisdictions are expected to submit Phase II WIPs that provide local area pollution targets
for implementation on a smaller scale; the timeframe for these Phase II WIPs will be determined
in early 2011. Phase III WIPs in 2017 are expected to be designed to provide additional detail of
restoration actions beyond 2017 and ensure that the 2025 goals are met.
ES-14 December 29, 2010
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Chesapeake Bay TMDL
Contents
SECTION 1. Introduction 1-1
1.1 TMDLs and the CWA 1-2
1.2 History of the Chesapeake Bay TMDL 1-3
1.2.1 Regulatory and Management Initiatives 1-3
1.2.2 Partnership Commitment to Develop the Chesapeake Bay TMDL 1-8
1.2.3 President's Chesapeake Bay Executive Order 1-10
1.3 Bay TMDL Process, Partner Coordination and Responsibilities.
1.3.1 CBP Partnership and Organizational Structure.
1.4 Legal Framework for the Chesapeake Bay TMDL.
1.4.1 What is a TMDL?
1.4.2 Why is EPA establishing this TMDL?.,
-11
-11
-15
-15
-16
SECTION 2. Watershed and Impairment Description 2-1
2.1 General Watershed Setting .'. 2-1
2.2 Chesapeake Bay TMDL Scope 2-6
2.2.1 Pollutants of Concern 2-7
2.2.2 Chesapeake Bay Program Segmentation Scheme 2-7
2.2.3 Jurisdictions' 2008 303(d) Listings 2-14
2.2.4 2008 303(d) Listing Segments Compared to Consent Decree and MOU Segments 2-15
SECTIONS. Chesapeake Bay Water Quality Standards 3-1
3.1 Chesapeake Bay Water Quality Criteria and Designated Uses 3-2
3.1.1 Tidal Water Designated Uses 3-4
3.1.2 Dissolved Oxygen Criteria 3-9
3.1.3 Chlorophyll a Criteria 3-11
3.1.4 Water Clarity/Underwater Bay Grasses Criteria 3-11
3.2 Jurisdictions' Current Chesapeake Bay Water Quality Standards Regulations 3-15
3.2.1 Delaware 3-15
3.2.2 District of Columbia 3-15
3.2.3 Maryland 3-16
3.2.4 Virginia '. 3-17
3.3 Assessing Attainment of Chesapeake Bay Water Quality Standards 3-18
3.3.1 Defining Total Exceedances.. 3-18
3.3.2 Defining Allowable Exceedances 3-20
3.3.3 Assessing Criteria Attainment : 3-22
SECTION 4. Sources of nitrogen, phosphorus and Sediment to the Chesapeake Bay 4-1
4.1 Jurisdiction Loading Contributions 4-1
4.2 Major River Basin Contributions 4-3
4.3 Pollutant Source Sector Contributions 4-5
4.4 Regulated Point Sources 4-6
4.4.1 Significant and Nonsignificant Municipal and Industrial Facilities 4-7
4.4.2 Basinwide NPDES Permitting Approach 4-8
4.5 Regulated Point Source Load Summaries 4-9
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4.5.1 Municipal Wastewater Discharging Facilities 4-9
4.5.2 Industrial Discharge Facilities 4-13
4.5.3 Combined Sewer Overflows 4-17
4.5.4 Sanitary Sewer Overflows 4-21
4.5.5 NPDES Permitted Stormwater 4-22
4.5.6 Concentrated Animal Feeding Operations 4-25
4.6 Nonpoint Sources 4-28
4.6.1 Agriculture 4-29
4.6.2 Atmospheric Deposition 4-33
4.6.3 Forest Lands 4-36
4.6.4 On-site Wastewater Treatment Systems 4-37
4.6.5 Nonregulated Stormwater Runoff 4-38
4.6.6 Oceanic Inputs 4-39
4.6.7 Streambank and Tidal Shoreline Erosion -. 4-41
4.6.8 Tidal Resuspension 4-42
4.6.9 Wildlife 4-43
4.6.10 Natural Background 4-44
SECTION 5. Chesapeake Bay Monitoring and Modeling Frameworks. 5-7
5.1 Technical Monitoring and Modeling Requirements 5-1
5.2 Bay Monitoring Framework Overview 5-2
5.2.1 Partnership's Chesapeake Bay Tidal Monitoring Network 5-3
5.2.2 Partnership's Watershed Monitoring Network 5-12
5.2.3 Data Quality and Access 5-14
5.2.4 Data Submission and Quality Assurance 5-16
5.2.5 Monitoring Applications in Chesapeake Bay TMDL Development 5-18
5.3 Modeling Framework Overview . , 5-18
5.4 Chesapeake Bay Airshed Model 5-21
5.5 Chesapeake Bay Land Change Model 5-24
5.5.1 Motivations for Developing Future Land Use Estimates 5-24
5.5.2 Scale of Chesapeake Bay Land Change Model Future Land Use Estimates 5-24
5.5.3 Components of Chesapeake Bay Land Change Model Future Land Use Estimates 5-26
5.6 Chesapeake Bay SPARROW Model 5-27
5.7 Chesapeake Bay Scenario Builder 5-28
5.8 Phase 5.3 Chesapeake Bay Watershed Model 5-30
5.8.1 Bay Watershed Model Segmentation 5-30
5.8.2 Bay Watershed Model Setup 5-32
5.8.3 Pollutant Source Representation : 5-37
5.8.4 Calibration 5-38
5.9 Chesapeake Bay Water Quality and Sediment Transport Model 5-38
5.9.1 Nonpoint Source Loads 5-41
5.9.2 Point Source Loads 5-41
5.9.3 Atmospheric Loads 5-41
5.9.4 Bank Loads 5-42
5.9.5 Wetlands 5-42
5.9.6 Model Setup 5-42
5.10 Chesapeake Bay Criteria Assessment Program 5-43
5.11 Climate Change Simulation 5-43
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SECTION 6. Establishing the Allocations for the Basin-Jurisdictions 6-1
6.1 Establishing the Overall Model Parameters 6-2
6.1.1 Hydrologic Period .6-2
6.1.2 Seasonal Variation 6-3
6.1.3 Daily Loads 6-5
6.2 Establishing the Nitrogen and Phosphorus Related Model Parameters 6-8
6.2.1 Critical Conditions ; 6-8
6.2.2 Assessment Procedures for DO and Chlorophyll a Standards 6-9
6.2.3 Addressing Reduced Sensitivity to Load Reductions at Low Nonattainment Percentages 6-10
6.2.4 Margin of Safety 6-13
6.3 Methodology for Establishing the Basin-Jurisdiction Allocations for Nitrogen and
Phosphorus 6-16
6.3.1 Accounting for Relative Effectiveness ofthe Major River Basins on Tidal Water Quality 6-17
6.3.2 Determining Controllable Load 6-20
6.3.3 Relating Relative Impact to Needed Controls (Allocations) 6-24
6.4 Establishing the Basin-Jurisdiction Allocations for Nitrogen and Phosphorus 6-25
6.4.1 Setting the Atmospheric Nitrogen Deposition Allocation 6-26
6.4.2 Determining the Basinwide Nitrogen and Phosphorus Target Load Based on Dissolved
Oxygen 6-28
6.4.3 Allocating Nitrogen and Phosphorus Loads to Jurisdictions within the Bay Watershed 6-30
6.4.4 Resolving Dissolved Oxygen and Chlorophyll a Nonattaining Bay Segments 6-32
6.4.5 Allocation Considerations for the Headwater Jurisdictions (New York and West Virginia) 6-38
6.4.6 Nitrogen-to-Phosphorus Exchanges 6-39
6.5 Establishing the Sediment-Related Model Parameters 6-41
6.5.1 Critical Conditions for Water Clarity and SAV 6-41
6.5.2 Assessment Procedures for the Clarity and SAV Standards 6-42
6.5.3 Addressing Reduced Sensitivity to Load Reductions at Low Nonattainment Percentages 6-43
6.5.4 Explicit Margin of Safety for Sediment 6-44
6.6 Establishing the Basin-Jurisdiction Allocations for Sediment 6-44
6.6.1 Methodology for Determining Sediment Allocations 6-45
6.6.2 Addressing Water Clarity/SAV Nonattaining Segments 6-45
6.7 Basin-Jurisdiction Allocations to Achieve the Bay WQS 6-48
6.7.1 Basin-Jurisdiction Allocations Tables 6-48
6.7.2 Correction ofthe West Virginia Sediment Allocation 6-48
6.8 Attainment of the District of Columbia pH Water Quality Standard 6-49
SECTION 7. Reasonable Assurance and Accountability Framework 7-1
7.1 Reasonable Assurance 7-1
7.1.1 Overview of the Accountability Framework 7-2
7.1.2 Federal Strategy 7-3
7.1.3 Funding 7-4
7.1.4 Air Emission Reductions 7-4
7.2 Accountability Framework 7-4
7.2.1 Watershed Implementation Plans 7-6
7.2.2 Two-Year Milestones 7-8
7.2.3 Chesapeake Bay TMDL Tracking and Accountability System 7-10
7.2.4 Federal EPA Actions 7-11
iii December 29, 2010
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Chesapeake Bay TMDL
SECTION 8. Watershed Implementation Plan Evaluation and Resultant Allocations 8-1
8.1 WIP Evaluation Methodology 8-3
8.1.1 Quantitative Evaluation of the Final Phase I WIPs 8-3
8.1.2 Qualitative Evaluation of the Final Phase I WIPs 8-4
8.2 WIP Evaluation Results 8-5
8.2.1 Target Allocation Attainment 8-5
8.2.2 Reasonable Assurance 8-9
8.3 Allocation Methodology 8-9
8.3.1 Backstop Allocation Methodology 8-10
8.3.2 Backstop Adjustment (Allocation Shift) Methodology 8-10
8.3.3 Assumptions Supporting the Allocations 8-12
8.4 Allocations by Jurisdiction 8-17
8.4.1 Delaware 8-17
8.4.2 District of Columbia 8-19
. 8.4.3 Maryland 8-20
8.4.4 New York 8-22
8.4.5 Pennsylvania 8-24
8.4.6 Virginia 8-27
8.4.7 West Virginia .- 8-30
8.5 Allocation Summary Chart 8-33
SECTION 9. Chesapeake Bay TMDLs 9-1
9.1 Bay Segment Annual and Daily Allocations to Meet WQS 9-1
SECTION 10. Implementation and Adaptive Management 10-1
10.1 Future Growth 10-1
10.1.1 Designating Target Loads for New or Increased Sources 10-1
10.1.2 Offset Programs 10-1
10.1.3 Additional Offset Program Features 10-2
10.1.4 EPA's Oversight Role of Jurisdictions'Offset Programs 10-3
10.2 Water Quality Trading 10-3
10.3 Future Modifications to the Chesapeake Bay TMDL 10-4
10.4 Federal Facilities and Lands 10-5
10.5 Factoring in Effects from Continued Climate Change 10-7
10.6 Sediment behind the Susquehanna River Dams 10-7
10.7 Filter Feeders , 10-8
SECTION 11. Public Participation 11-1
11.1 Stakeholder and Local Government Outreach and Involvement 11-1
11.1.1 Open Collaboration with Stakeholders 11-1
11.1.2 Outreach to Local Governments and Elected Officials 11-1
11.1.3 Local Pilots 11-2
11.2 Public Outreach 11-2
11.2.1 Public Meetings 11-2
11.2.2 Webinars to Expand Audiences 11-4
11.2.3 Chesapeake Bay TMDL Website 11-5
11.2.4 Public Notices 11-5
iv December 29, 2010
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Chesapeake BayTMDL
11.3 Responses to Public Comments 11-5
11.4 Interaction with States, D.C. on Watershed Implementation Plans 11-6
SECTION 12. References 12-1
SECTION 13. Glossary 13-1
SECTION 14. Abbreviations. 14-1
Appendices
Appendix A Chesapeake Bay TMDL Contributors
Appendix B Index of Documents Supporting the Chesapeake Bay TMDL
Appendix C Record of Chesapeake Bay TMDL Related Chesapeake Bay Program Committee,
Team and Workgroup and Partner/Stakeholder Meetings
Appendix D Evaluation of the Most Protective Chesapeake Bay Dissolved Oxygen Criteria
Appendix E Summary of Initial Climate Change Impacts on the Chesapeake Bay Watershed
Flows and Loads
Appendix F Determination of the Hydrologic Period for Model Application
Appendix G Determination of Critical Conditions for the Chesapeake Bay TMDL
Appendix H Criteria Assessment Procedures using Model Scenario Output with Bay
Monitoring Data
Appendix I Documentation of the Reduced Sensitivity to Load Reductions at Low
Nonattainment Percentages
Appendix J Key Chesapeake Bay TMDL Reference and Management Model Scenarios:
Definitions and Descriptions
Appendix K Allocation Methodology for Relating Relative Impact to Needed Controls
Appendix L Setting the Chesapeake Bay Atmospheric Nitrogen Deposition Allocations
Appendix M Chesapeake Bay Water Quality/Sediment Transport Model Management Scenario
Attainment Assessment Results and 2008 303(d) Chesapeake Bay List
Assessment Results
Appendix M-l Chesapeake Bay Dissolved Oxygen Criteria Attainment
Assessment Results
Appendix M-2 Chesapeake Bay Chlorophyll a Criteria Attainment
Assessment Results
Appendix M-3 Chesapeake Bay Water Clarity/SAV Criteria Attainment
Assessment Results
Appendix M-4 Chesapeake Bay Segments 2008 303(d) List Assessment
Results
Appendix N Resolution of Segments Failing to Attain the Applicable Criteria
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Appendix O Setting the Chlorophyll a Criteria-Based Nutrient Allocations for the James River
Watershed
Appendix P Setting the Water Clarity/SAV Criteria-Based Sediment Allocations
Appendix Q Detailed Annual Chesapeake Bay TMDL WLAs and LAs
Appendix R Chesapeake Bay TMDL Daily WLAs and LAs
Appendix S Offsets for New or Increased Loadings of Nitrogen, Phosphorus and Sediment to
the Chesapeake Bay Watershed
Appendix T Sediment behind the Susquehanna Dams Technical Documentation
Appendix U Accounting for the Benefits of Filter Feeder Restoration Technical
Documentation
Appendix V Best Management Practice (BMP) Implementation Rates for Final Scenarios
Appendix W Responses to Public Comments Received on the September 24, 2010, Draft
Chesapeake Bay TMDL
Appendix X Staged Implementation Approach for Wastewater Treatment Facilities in the
Virginia James River Basin
VI
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Chesapeake Bay TMDL
Tables
Table ES-1. Chesapeake Bay TMDL watershed nitrogen, phosphorus and sediment final
allocations by jurisdiction and by major river basin ES-7
Table 1-1. URLs for accessing the seven Chesapeake Bay watershed jurisdictions'
tributary strategies 1-7
Table 1-2. Summary of Chesapeake Bay TMDL relevant actions agreed to by the
CBP's Principals' Staff Committee during its October 1, 2007, meeting 1-9
Table 1-3. Virginia consent decree (CD) waters impaired for dissolved oxygen (DO)
and/or nutrients addressed by the Chesapeake Bay TMDL 1-18
Table 1-4. District of Columbia consent decree (CD) waters impaired for pH addressed
by the Chesapeake Bay TMDL 1-19
Table 2-1. The Chesapeake Bay 303(d) tidal segments with consent decree
(CD)/memorandum of understanding (MOU) and 303(d) listing status by
major river basin and jurisdiction 2-10
Table 2-2. Comparison of consent decree/MOU segments with total number of Bay
segments 2-15
Table 3-1. Chesapeake Bay water quality criteria and designated use related
documentation and addenda 3-2
Table 3-2. Five Chesapeake Bay tidal waters designated uses 3-4
Table 3-3. Current tidal water designated uses by Chesapeake Bay segment 3-6
Table 3-4. Current Chesapeake Bay DO criteria., 3-10
Table 3-5. Summary of Chesapeake Bay water clarity criteria for application to
shallow-water Bay grass designated use habitats 3-12
Table 3-6. Chesapeake Bay SAV restoration acreage goals and application depths 3-12
Table 3-7. Links for accessing the current waters quality standards (WQS) regulations
for Delaware, the District of Columbia, Maryland, and Virginia 3-15
Table 3-8. District of Columbia designated uses for surface waters 3-16
Table 3-9. Numeric criteria for the District of Columbia's tidally influenced waters 3-16
Table 3-10. Segment-specific chlorophyll a criteria for Virginia's tidal James River
waters 3-17
Table 3-11. Estimated percent spatial criteria exceedances and associated cumulative
probabilities 3-19
Table 4-1. Percentage of total nitrogen delivered to the Bay from each jurisdiction by
pollutant source sector 4-5
Table 4-2. Percentage of total phosphorus delivered to the Bay from each jurisdiction
by pollutant source sector 4-5
Table 4-3. Percentage of sediment delivered to the Bay from each jurisdiction by
pollutant source sector 4-6
Table 4-4. Jurisdiction-specific definitions of significant municipal and industrial
wastewater discharge facilities 4-7
Table 4-5. Significant and nonsignificant municipal and industrial wastewater
discharging facilities by jurisdiction as of December 2010 4-8
Table 4-6. Nitrogen and phosphorus permit tracking summary under the Basinwide
NPDES Wastewater Permitting Approach, through December 2010 4-9
Table 4-7. Municipal wastewater facilities by jurisdiction 4-10
VII
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Chesapeake Bay TMDL
Table 4-8. Model estimated 2009 municipal wastewater loads by jurisdiction delivered
to Chesapeake Bay 4-10
Table 4-9. Model estimated 2009 municipal wastewater loads by major river basin
delivered to Chesapeake Bay 4-10
Table 4-10. Industrial wastewater facilities 4-14
Table 4-11. 2009 Load estimates of industrial facility discharges 4-14
Table 4-12. 2009 Flow, total nitrogen, and total phosphorus load estimates of industrial
wastewater facility discharges by major river basin 4-14
Table 4-13. Combined sewer system communities in the Bay watershed 4-18
Table 4-14. NPDES stormwater permittees by jurisdiction and in the Chesapeake Bay
watershed, summer 2009 4-25
Table 4-15. Federal numeric thresholds for small, medium, and large CAFOs 4-26
Table 4-16. Estimated number of state or federal permitted CAFOs 4-28
Table 4-17. Estimated portion of deposited NOx loads on the Chesapeake watershed
from four source sectors—EGUs, mobile sources, industry, and all other
sources in 1990 and 2020 4-36
Table 4-18. Chesapeake Bay Water Quality and Sediment Transport Model -simulated
SAV acres under a range of sediment scoping scenarios compared with the
2010 Tributary Strategy scenario 4-44
Table 5-1. Modeling tools supporting development of the Chesapeake Bay TMDL 5-20
Table 5-2. Phase 5.3 Chesapeake Bay Watershed Model land uses 5-33
Table 6-1. ADM for calculating daily maximum loads 6-7
Table 6-2. Different approaches available under the explicit and implicit MOS types 6-14
Table 6-3. Relative effectiveness (measured as DO concentration per edge-of-stream
pound reduced) for nitrogen and phosphorus for watershed jurisdictions by
major river basin and above and below the fall line 6-19
Table 6-4. Pollutant sources as defined for the No Action and E3 model scenarios 6-23
Table 6-5. Chesapeake Bay designated use segments showing percent nonattainment of
the applicable Bay DO WQS under the basinwide nitrogen and phosphorus
target loadings (million pounds per year) •• 6-33
Table 6-6. Tributary strategy scenario and nitrogen and phosphorus-based allocation
scenario's total suspended solids loads (millions of pounds) by watershed
jurisdiction 6-43
Table 6-7. Chesapeake Bay watershed nitrogen and phosphorus and sediment
allocations by major river basin by jurisdiction to achieve the Chesapeake
Bay WQS 6-50
Table 6-8. Chesapeake Bay watershed nitrogen and phosphorus and sediment
allocations by jurisdiction by major river basin to achieve the Chesapeake
Bay WQS 6-51
Table 7-1. Eight elements of the jurisdictions' Watershed Implementation Plans 7-6
Table 7-2. Comparison of elements within the Chesapeake Bay TMDL and Phase I, II,
andHIWIPs 7-7
Table 8-1. Comparison between nitrogen, phosphorus, and sediment jurisdiction-wide
allocations and final Phase I Watershed Implementation Plans, in millions of
pounds per year 8-6
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Chesapeake Bay TMDL
Table 8-2. Comparison between the nitrogen, phosphorus, and sediment basin-
jurisdiction allocations and final Phase I Watershed Implementation Plans, in
million pounds per year 8-7
Table 8-3. Percent reductions in edge-of-stream loads to achieve urban stormwater
WLAs 8-14
Table 8-4. EPA backstop allocations, adjustments, and actions based on assessment of
final Phase I WIPs 8-16
Table 8-5. Chesapeake Bay watershed nitrogen, phosphorus, and sediment allocations
by jurisdiction and by major river basin, in millions of pounds per year 8-33
Table 9-1. Chesapeake Bay TMDL total nitrogen (TN) annual allocations (pounds per
year) by Chesapeake Bay segment to attain Chesapeake Bay WQS 9-2
Table 9-2. Chesapeake Bay TMDL total phosphorus (TP) annual allocations (pounds
per year) by Chesapeake Bay segment to attain for the proposed amended
Chesapeake Bay WQS '. 9-7
Table 9-3. Chesapeake Bay TMDL sediment (TSS) annual allocations (pounds per
year) by Chesapeake Bay segment to attain Chesapeake Bay WQS 9-12
Table 9-4. Edge of Stream (EOS) WLAs (Annual) for the 478 significant permitted
dischargers to meet TMDLs to attain the Chesapeake Bay WQS 9-17
IX
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Chesapeake Bay TMDL
Figures
Figure ES-1. A nitrogen, phosphorus and sediment TMDL has been developed for each
of the 92 Chesapeake Bay segment watersheds ES-4
Figure ES-2. Sub-basins across the Chesapeake Bay watershed with the highest (red) to
lowest (blue) pound for pound nitrogen pollutant loading effect on
Chesapeake Bay water quality ES-6
Figure 1-1. CBP's organizational structure 1-12
Figure 2-1. The Chesapeake Bay watershed with major rivers and cities 2-2
Figure 2-2. Hydrogeomorphic regions of the Chesapeake Bay watershed 2-3
Figure 2-3. Chesapeake Bay watershed land cover 2-5
Figure 2-4. Reported and projected human population growth in the Chesapeake Bay
watershed 1950-2030 2-6
Figure 2-5. The 92 Chesapeake Bay segments 2-8
Figure 2-6. The 92 Chesapeake Bay segment watersheds 2-9
Figure 3-1. Conceptual illustration of the five Chesapeake Bay tidal water designated use
zones 3-5
Figure 3-2. Dissolved oxygen concentrations (mg/L) required by different Chesapeake
Bay species and biological communities 3-9
Figure 3-3. Example cumulative frequency distribution (CFD) curve 3-19
Figure 3-4. Default reference curve used in the attainment assessment of Chesapeake
Bay water quality criteria for which biologically based reference curves have
not yet been derived 3-21
Figure 3-5. Example reference and assessment curves showing allowable and non-
allowable exceedances 3-21
Figure 3-6. Direct model assessment of open water (a), and deep water and deep channel
(b) criteria 3-24
Figure 4-1. Modeled estimated total nitrogen loads delivered to the Chesapeake Bay by
jurisdiction in 2009 4-1
Figure 4-2. Model estimated total phosphorus loads delivered to the Chesapeake Bay by
jurisdiction in 2009 4-2
Figure 4-3. Model estimated total sediment loads delivered to the Chesapeake Bay by
jurisdiction in 2009 4-2
Figure 4-4. Model estimated total nitrogen loads delivered to the Chesapeake Bay by
major tributary in 2009 4-3
Figure 4-5. Model estimated total phosphorus loads delivered to the Chesapeake Bay by
major tributary in 2009 4-4
Figure 4-6. Model estimated total sediment loads delivered to the Chesapeake Bay by
major tributary in 2009 4-4
Figure 4-7. Significant wastewater treatment facilities in the Chesapeake Bay watershed 4-11
Figure 4-8. Nonsignificant municipal wastewater treatment facilities in the Chesapeake
Bay watershed 4-12
Figure 4-9. Significant industrial wastewater discharge facilities in the Chesapeake Bay
watershed 4-15
Figure 4-10.Nonsignificant industrial wastewater discharge facilities in the Chesapeake
Bay watershed 4-16
Figure 4-ll.CSO communities in the Chesapeake Bay watershed 4-20
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Chesapeake Bay TMDL
Figure 4-12.Phase I and II MS4s in the Chesapeake Bay watershed 4-24
Figure 4-13.1985 and 2009 modeled total nitrogen, phosphorus, and sediment loads from
agricultural lands across the Chesapeake Bay watershed 4-30
Figure 4-14.2007 Chesapeake Bay watershed poultry populations by jurisdiction 4-31
Figure 4-15.2007 Chesapeake Bay watershed livestock populations by jurisdiction 4-32
Figure 4-16.Principle area of NOX emissions (outlined in blue) that contribute nitrogen
deposition to the Chesapeake Bay and its watershed (solid blue fill) (the Bay
airshed) 4-34
Figure 4-17 Trend of estimated average nitrate and ammonia deposition concentrations in
the Phase 5 Model domain from 1984 to 2005 4-35
Figure 4-18. Estimated 2001 annual total deposition of nitrogen (kg/ha) to North America
and adjacent coastal ocean 4-40
Figure 4-19. Relative estimates of sources of erosion from land sources (crop, forest, or
construction) or bank sources banks and ditch beds) 4-41
Figure 4-20. Sources of total suspended solids in the Chesapeake including the two
components of shoreline erosions, fastland and nearshore erosion 4-42
Figure 4-21. Estimated tidal sediment inputs for 1990 from the Chesapeake Bay
watershed and from shore erosion. Shoreline sediment inputs (here labeled
bank load) are estimated to be about equal to watershed inputs (here labeled
as nonpoint source) 4-43
Figure 5-1. Tidal Chesapeake Bay water quality monitoring network stations 5-4
Figure 5-2. Shallow-water monitoring illustrating segment completion and latest rotation
for Maryland 5-7
Figure 5-3. 2003-2008 Chesapeake Bay stratified random benthic sampling sites used to
estimate habitat impairment through benthic community condition
assessment 5-8
Figure 5-4. Flightlines for the annual Chesapeake Bay SAV Aerial Survey 5-9
Figure 5-5. Illustration of mapped SAV beds, individual bed coding, bed density
estimates, and species identification (from ground surveys) 5-10
Figure 5-6. Chesapeake Bay watershed monitoring network 5-13
Figure 5-7. Chesapeake Bay tidal and watershed water quality monitoring networks'
participants arrayed by their role in sample collection, laboratory analysis,
and/or data reporting 5-17
Figure 5-8. Chesapeake Bay TMDL modeling framework 5-19
Figure 5-9. Atmospheric deposition monitoring stations used in the Chesapeake Bay
airshed nitrogen wet deposition regression model 5-22
Figure 5-10. The Community Muldscale Air Quality Model's 12 km grid over the Phase
5.3 Chesapeake Bay Watershed Model county segmentation 5-23
Figure 5-11. 2006 Land cover conditions in the Chesapeake Bay watershed and
intersecting counties 5-25
Figure 5-12. An example of the Chesapeake Bay SPARROW Model output showing
delivered yields of total nitrogen in the Chesapeake Bay watershed 5-28
Figure 5-13. Scenario Builder conceptual process. 5-29
Figure 5-14. Segmentation and reach simulation of the Phase 5.3 Chesapeake Bay
Watershed Model 5-31
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Chesapeake Bay TMDL
Figure 5-15. Phase 5.3 Chesapeake Bay Watershed Model hydrology (upper panel) and
water quality (lower panel) monitoring calibration stations overlaid on the
Phase 5.3 Bay Watershed Model's river segments 5-39
Figure 5-16. The detailed 57,000 cell grid of the Chesapeake Bay Water Quality and
Sediment Transport Model 5-40
Figure 6-1. Graphic comparison of allowable exceedance compared to actual
exceedance 6-11
Figure 6-2. Example of DO criteria nonattainment results from a wide range of nitrogen
and phosphorus load reduction model scenarios. 6-12
Figure 6-3. Example of a James River segment's spring chlorophyll a WQS
nonattainment results from a wide range of TN loading Chesapeake Bay
Water Quality Model scenarios 6-13
Figure 6-4. Relative effectiveness for nitrogen for the watershed jurisdictions and major
rivers basins, above and below the fall line, in descending order 6-20
Figure 6-5. Relative effectiveness illustrated geographically by subbasins across the
Chesapeake Bay watershed for nitrogen 6-21
Figure 6-6. Relative effectiveness for illustrated geographically by subbasins across the
Chesapeake Bay watershed for phosphorus 6-22
Figure 6-7. Allocation methodology example showing the hockey stick and straight line
reductions approaches, respectively, to wastewater (red line) and all other
sources (blue line) for nitrogen , 6-25
Figure 6-8. Principal areas of nitrogen oxide (blue line) and ammonia (red line)
emissions that contribute to nitrogen deposition to the Chesapeake Bay and
its watershed (dark blue fill) 6-27
Figure 6-9. Chesapeake Bay water quality model simulated DO criteria attainment under
various TN and TP loading scenarios 6-29
Figure 6-10.Example allocation methodology application for phosphorus 6-31
Figure 6-11.Example allocation methodology application for nitrogen 6-31
Figure 6-12.Potomac River chlorophyll a monitoring data compared with the District's
summer seasonal mean chlorophyll a water quality criteria 6-36
Figure 6-13.Tidal James River monitoring data for chlorophyll a at station TF5.5 (in the
upper tidal James River near Hopewell, Virginia) compared to Virginia's
James River segment-season specific chlorophyll a criteria 6-37
Figure 6-14.James River nonattainment of the chlorophyll a WQS at various load
scenarios 6-38
Figure 6-15.TN:TP exchanges based on anoxic volume days and varying TP loads 6-40
Figure 6-16.TN: TP exchanges based on chlorophyll a concentrations and varying TP
loads. 6-40
Figure 6-17. Chesapeake Bay SAV/Water Clarity WQS attainment from monitoring data
assessment '. 6-46
Figure 6-18.Model simulated sediment loads by scenario compared with the range of
sediment allocations (billions of pounds per year as total suspended
sediment) 6-49
Figure 6-19. District of Columbia's Roosevelt Island station pH versus chlorophyll a
monitoring data regression 6-52
Figure 7-1. Relationship between WIPs and 2-year milestones 7-9
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Foreword
This document describes the technical, legal, and policy underpinnings of the Chesapeake Bay
Total Maximum Daily Load (TMDL). While EPA Regions 2 and 3 are establishing this TMDL,
it represents the product of decades of scientific research, monitoring, assessment, and model
application, and years of focused dialogue and analysis among EPA, our six watershed state
partners and the District of Columbia, and numerous stakeholders. This document has benefited
from the input of thousands of professionals and citizens dedicated to the restoration of the
Chesapeake Bay. In accordance with the Clean Water Act and Executive Order 13508 (signed by
President Obama on May 12, 2009), the Chesapeake Bay TMDL provides a critical plan to
restore and maintain the living resources of the Chesapeake Bay.
A TMDL is required by the Clean Water Act for waters that are on state lists identifying waters
that are impaired - i.e., not attaining state adopted and EPA approved water quality standards.
Most of the waters of the Chesapeake Bay and its tidal tributaries and embayments are on the
three states' (Maryland, Virginia, and Delaware) and the District's lists of impaired waters
because of excess nitrogen, phosphorus, and sediment pollution. The Chesapeake Bay TMDL
identifies the loadings of nitrogen, phosphorus, and sediment that are necessary to achieve the
applicable jurisdiction's water quality standards for the Bay and its tidal tributaries and
embayments for dissolved oxygen, chlorophyll a (an indicator of algae), water clarity, and
submerged aquatic vegetation (SAV, or underwater Bay grasses). For this reason, the
Chesapeake Bay TMDL has been described as a pollution diet defining the pollutant loadings
necessary to attain water quality standards and restore the aquatic life resources of the
Chesapeake Bay.
The Chesapeake Bay receives waters from thousands of streams and rivers within seven
jurisdictions in the mid-Atlantic region of the United States: Delaware, the District of Columbia,
Maryland, New York, Pennsylvania, Virginia, and West Virginia. These waters drain to the
Chesapeake Bay and, therefore, contribute pollutant loadings to the Bay. The Chesapeake Bay
TMDL also establishes total maximum daily loads from these watersheds and jurisdictions for
each of the 92 impaired segments that comprise the waters of the Chesapeake Bay and its tidal
tributaries and embayments. Thus, the Chesapeake Bay TMDL is actually an assemblage of 276
TMDLs: individual TMDLs for each of the 3 pollutants— nitrogen, phosphorus, and sediment—
for each of the 92 segments (3 x 92 = 276).
The purpose of the Chesapeake Bay TMDL is to identify the pollutant loading reductions needed
to meet the applicable Bay water quality standards. The TMDL, thus, allocates loads to all
pollutant source sectors in aH parts of the Bay's 64,000 square mile watershed. Because of the
watershed-wide nature of these loading reductions, the water quality benefits from these
reductions will not be limited to the Bay and its tidal tributaries and embayments. In fact, the
watershed's headwaters from the location the pollutant reductions are made to the point they
enter the Bay or its tidal tributaries should benefit from some measure of improved water quality.
The controls necessary to reduce nitrogen, phosphorus, and sediment also are likely to reduce
other pollutants like bacteria and chemical contaminants.
While the Chesapeake Bay TMDL establishes the pollutant loadings for nitrogen, phosphorus,
and sediment needed to restore and maintain a healthy Bay, the TMDL is essentially an
xiii December 29, 2010
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Chesapeake Bay TMDL
information and planning tool that does not, by itself, implement the needed controls.
Implementation mechanisms available under other provisions of the Clean Water Act, Clean Air
Act, state laws, and federal and state regulations, and local ordinances, as well as appropriate
levels of funding, are needed to achieve these loading targets. The Bay TMDL will be
implemented using an accountability framework that includes the seven jurisdictions' Watershed
Implementation Plans (WIPs), two-year milestones, EPA's tracking and assessment of
restoration progress and, as necessary, specific federal actions if the Bay watershed jurisdictions
do not meet their targets and commitments. Although not itself an element of the Chesapeake
Bay TMDL, the accountability framework is being established pursuant to both section 117(g)(l)
of the Clean Water Act and Executive Order 13508, in part, to demonstrate reasonable assurance
that the Chesapeake Bay TMDL allocations for nitrogen, phosphorus, and sediment and the
jurisdictions' water quality standards are met.
An executive summary provides an overview of the TMDL, highlighting its more important
aspects. For more specific information, readers should consult the main document, which
describes each aspect of the Chesapeake Bay TMDL in detail. Finally, for additional background
and supportive material, the reader is referred to the references contained in the main document
and numerous appendices.
Shawn M. Garvin, Regional Administrator
U.S. Environmental Protection Agency Region 3
Judith A. Enck, Regional Administrator
U.S. Environmental Protection Agency Region 2
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Acknowledgements
This document was developed through the collaborative efforts of the U.S. Environmental
Protection Agency (EPA) and its seven Chesapeake Bay watershed partners—Delaware, the
District of Columbia, Maryland, New York, Pennsylvania, Virginia, and West Virginia—
principally through the Chesapeake Bay Program's (CBP) Water Quality Goal Implementation
Team (WQGIT) (formerly the Water Quality Steering Committee), its principal workgroups, and
the former Nutrient Subcommittee. The CBP's Principals' Staff Committee made decisions on
behalf of the partnership and provided policy direction to the WQGIT. Advice, direction, and
independent peer review were provided by the CBP's Scientific and Technical Advisory
Committee (STAC), the Local Government Advisory Committee (LGAC), and the Citizen's
Advisory Committee (CAC). Comments and recommendations gathered through the November-
December 2009 public meetings/webinars, the monthly webinars scheduled during 2010, and the
September—November 2010 public comment period were instrumental in ensuring that the
published allocations provide the most benefits to local streams and rivers and still achieve the
jurisdictions' Chesapeake Bay water quality standards.
The document resulted from the collaborative expertise, input, feedback, and formal comments
of thousands of individuals from the multitude of CBP partnering agencies and institutions, local
governments, nongovernmental organizations, businesses, many other involved stakeholders, and
the general public. Their individual and collective contributions are hereby acknowledged.
Special acknowledgment is made to past and present members the following CBP committees:
WQGIT, Principals' Staff Committee, Management Board, STAC, LGAC, CAC, Agriculture
Workgroup, Forestry Workgroup, Sediment Workgroup, Urban and Suburban Stormwater
Workgroup, Wastewater Treatment Workgroup, Watershed Technical Workgroup, TMDL
Workgroup (formerly Reevaluation Technical Workgroup), the former Nutrient Subcommittee,
Scientific and Technical Analysis and Reporting Team, Criteria Assessment Procedures
Workgroup, Modeling Workgroup, Nontidal Water Quality Workgroup, Tidal Monitoring and
Analysis Workgroup, Analytical Methods and Quality Assurance Workgroup, and former
Monitoring and Analysis Subcommittee. Appendix A provides a detailed member listing of these
committees, teams, and workgroups who were instrumental in completing the Chesapeake Bay
total maximum daily load (TMDL).
Special acknowledgement is also made to the following individuals (in alphabetical order) for
their contributions to the development of the Bay TMDL, support of the development of the
jurisdictions' Phase I Watershed Implementation Plans (WIPs), evaluation of the draft and final
Phase I WIPs, supporting public and stakeholder outreach, responding to thousands of public
comments, and publication of this document: Greg Allen, EPA Region 3 CBP Office; Katherine
Antos, EPA Region 3 CBP Office; Cheryl Atkinson, EPA Region 3 Water Protection Division
(WPD); Seth Ausubel, EPA Region 2 Division of Environmental Planning and Protection;
Michael Barnes, Chesapeake Research Consortium/CBP Office; Greg Barranco, EPA Region 3
CBP Office; Richard Batiuk, EPA Region 3 CBP Office; Benita Best-Wong, EPA Office of
Water; Carin Bisland, EPA Region 3 CBP Office; Ross Brennan, EPA Office of Water; Kevin
Bricke, EPA Region 2 Division of Environmental Planning and Protection; Chris Brosch,
University of Maryland/CBP Office; Brian Burch, EPA Region 3 CBP Office; Jon Capacasa,
EPA Region 3 WPD; Ann Carkhuff, EPA Region 3 WPD; Peter Claggett, U.S. Geological
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Chesapeake Bay TMDL
Survey (USGS)/CBP Office; Jeff Corbin, EPA Region 3 Office of the Regional Administrator;
James Curtin, EPA Office of General Counsel; Thomas Damm, EPA Region 3 WPD;
Christopher Day, EPA Region 3 Office of Regional Counsel; Kevin DeBell, EPA Region 3 CBP
Office; Robin Dennis, NOAA/EPA Office of Research and Development; Helene Drago, EPA
Region 3 WPD; Mark Dubin, University of Maryland/CBP Office; Jim Edward, EPA Region 3
CBP Office; Judith Enck, EPA Region 2 Regional Administrator; Leo Essenthier, EPA Region 3
WPD; Barbara Finazzo, EPA Region 2 Division of Environmental Planning and Protection;
Katie Foreman, University of Maryland/CBP Office; Kristin Foringer, Chesapeake Research
Consortium/CBP Office; Debra Forman, EPA Region 3 WPD; J. Charles Fox, EPA Office of the
Administrator; Michael Fritz, EPA Region 3 CBP Office; Elizabeth Gaige, EPA Region 3 WPD;
Angie Garcia, EPA Region 3 WPD; Shawn Garvin, EPA Region 3 Regional Administrator;
Kelly Gable, EPA Region 3 Office of Regional Counsel; Patricia Gleason, EPA Region 3 WPD;
Peter Gold, EPA Region 3 WPD; Aaron Gorka, Chesapeake Research Consortium/CBP Office;
Michelle Gugger, EPA Region 3 WPD; Michael Haire, EPA Office of Water; Denise Hakowski,
EPA Region 3 WPD; Suzanne Hall-Trevena, EPA Region 3 WPD; James Hanlon, EPA Office of
Water; Rachel Herbert, EPA Office of Water; Sara Hilbrich, EPA Office of Water; Amie Howe,
EPA Region 3 Office of State and Congressional Relations; Nan Ides, EPA Region 3 WPD; Fred
Irani, USGS/CBP Office; Ruth Izraeli, EPA Region 2 Division of Environmental Planning and
Protection; Jackie Johnson, Interstate Commission on the Potomac River Basin/CBP Office; Jeni
Keisman, University of Maryland/CBP Office; Victoria Kilbert, Chesapeake Research
Consortium/CBP Office; Robert Koroncai, EPA Region 3 WPD; Caitlin Kovelove, EPA Office
of Water; Amelia Letnes, EPA Office of Water; Mary Letzkus, EPA Region 3 WPD; Lewis
Linker, EPA Region 3 CBP Office; Felix Locicero, EPA Region 2 Division of Environmental
Planning and Protection; Travis Loop, EPA Region 3 CBP Office; Michael Mallonee, Interstate
Commission on the Potomac River Basin/CBP Office; Lori Mackey, EPA Region 3 CBP Office;
David McGuigan, EPA Region 3 WPD; Evelyn MacKnight, EPA Region 3 WPD; Mike Mason,
EPA Office of Water; Larry Merrill, EPA Region 3 WPD; Linda Miller, EPA Region 3 Office of
State and Congressional Relations; Jenny Molloy, EPA Region 3 CBP Office/WPD; Francis
Mulhern EPA Region 3 WPD; Elizabeth Ottinger, EPA Region 3 WPD; Andrew Parker, Tetra
Tech; Reggie Parrish, EPA Region 3 CBP Office; Jeffrey Potent, EPA Office of Water; Lucinda
Power, EPA Region 3 CBP Office; Andrew Prugar, EPA Office of Environmental Information;
Teresa Rafi, Tetra Tech; Pravin Rana, EPA Office of Water; Sucharith Ravi, University of
Maryland/CBP Office; Bill Richardson, EPA Region 3 WPD; Robert Rose, EPA Office of
Water; Jennifer Sincock, EPA Region 3 WPD; Mike Shapiro, EPA Office of Water; Gary Shenk,
EPA Region 3 CBP Office; Kelly Shenk, EPA Region 3 CBP Office; Rachel Streusand,
Chesapeake Research Consortium/CBP Office; Jeff Strong, Tetra Tech; Fred Suffian, EPA
Region 3 WPD; Gwen Supplee, EPA Region 3 WPD; Jeff Sweeney, University of *
Maryland/CBP Office; Nita Sylvester, EPA Region 3 CBP Office; Peter Tango, U.S. Geological
Survey/CBP Office; Renee Thompson, USGS/CBP Office; Brian Trulear, EPA Region 3 WPD;
Randy Waite, EPA Office of Air and Radiation; Tom Wail, EPA Office of Water; Ping Wang,
University of Maryland/CBP Office; Howard Weinberg, University of Maryland/CBP Office;
Steve Whitlock EPA Office of Water; Julie Winters, EPA Region 3 CBP Office; John Wolf,
USGS/CBP Office; Robert Wood, EPA Region 3 CBP Office; Jing Wu, University of
Maryland/CBP Office; Guido Yactayo, University of Maryland/CBP Office; Ning Zhou,
Virginia Polytechnical and State University/CBP Office; Kyle Zieba, EPA Region 3 WPD; and
Hank Zygmunt, EPA Region 3 WPD.
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Special acknowledgement of the policy direction and guidance provided by Lisa Jackson, EPA
Administrator; Robert Perciasepe, EPA Deputy Administrator; and Robert Sussman, Counselor
to the Administrator.
xvii December 29, 2010
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Members of the Chesapeake Bay Program's Water Quality Goal Implementation Team gather in Lancaster,
Pennsylvania, in April 2009 to discuss development of the Chesapeake Bay TMDL.
XVIII
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SECTION! INTRODUCTION
This document establishes total maximum daily loads (TMDLs) for nitrogen, phosphorus, and
sediment for the Chesapeake Bay and its tidal tributaries and embayments as required by section
303(d) of the Clean Water Act (CWA) and its implementing regulations at Title 40 of the Code
of Federal Regulations (CFR) section 130.7. This TMDL represents the culmination of decades
of collaboration among many partners and stakeholders and is the result of an analysis of water
quality pollution and its solution on an unprecedented geographic, scientific, programmatic, and
political scale. While all TMDLs are unique, this TMDL is distinguished by the magnitude of the
watershed it addresses and the wealth of science synthesized, data developed, and analyses
conducted over the course of the past decades that support its conclusions.
In an effort to keep the Chesapeake Bay TMDL (Bay TMDL) document as clear and succinct as
possible, discussion of the technical analyses and modeling that support the pollutant allocations
are reasonably summarized in nature with links provided to the more detailed technical support
documentation. Because of the large size of the watershed and the many individual sources, load
allocations (LAs) and wasteload allocations (WLAs) summarized in Section 9 are presented in
greater detail in supporting appendices.
This document is organized into 11 sections as follows:
• Section 1: Clean Water Act and regulatory, statutory, and historical background of the
Chesapeake Bay TMDL
• Section 2: Description of the Chesapeake Bay watershed, the Bay. and its impaired
segments
• Section 3: The jurisdictions' Chesapeake Bay water quality standards
• Section 4: The major sources of nutrients and sediment in the Bay, its watershed, and its
airshed
• Section 5: The modeling tools used to develop the WLAs and LAs
• Section 6: How the TMDL was developed, including the allocation methodology and
related considerations
• Section 7: Discussion of reasonable assurance, Bay TMDL implementation, and the Bay
TMDL accountability framework
• Section 8: The evaluation of jurisdictions' Watershed Implementation Plans
• Section 9: The individual nitrogen, phosphorus, and sediment TMDLs for each of the 92
Bay tidal segments
• Section 10: Adaptive management approach to Bay TMDL implementation
• Section 11: Documentation of public participation, comments, and responses
This document also contains three additional sections providing: a list of references (Section 12),
a glossary (Section 13), and a list of abbreviations (Section 14) and 24 Appendices.
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Additional supporting information that is not part of" this document or its appendices, can be
found as follows:
• Technical documentation for each of the Chesapeake Bay TMDL models and supporting
tools—Bay airshed, land change, Scenario Builder, SPARROW, Bay watershed. Bay water
quality and sediment transport, oyster filter feeder, and menhaden filter feeder—are
provided via URL links in Section 5.
• Access to each of the jurisdictions' final Phase I Watershed Implementation Plans (WIPs)
is provided via URL in Section 7. The WIPs are part of the accountability framework
meant to implement the Bay TMDL, but they are not an element of the Bay TMDL itself.
EPA reviewed the Phase I WIPs as part of the information used to inform its allocation
decisions.
• Publicly accessible agreements, documents, reports, papers, meeting summaries.
correspondence, and data sets developed during the decades and more recent years leading
up to the Chesapeake Bay TMDL, which were instrumental in setting the scientific,
programmatic, policy, and legal foundation on which the Bay TMDL is built, are listed in
Appendix B with electronic access to all through the provided URLs.
1.1 TMDLS AND THE CWA
Section 303(c) of the 1972 Clean Water Act (CWA) requires states, including the District of
Columbia, (collectively referred to as jurisdictions) to establish water quality standards (WQS)
that identify each waterbody's designated uses and the criteria needed to support those uses. The
CWA establishes a rebuttable presumption that all waters can attain beneficial aquatic life uses.
i.e., fishable and recreational (i.e., swimmable) uses.
Section 303(d) of the CWA requires states, including the District of Columbia, to develop lists of
impaired waters that fail to meet WQS set by jurisdictions even after implementing technology-
based and other pollution controls. EPA's regulations for implementing CWA section 303(d) are
codified in the Water Quality Planning and Management Regulations at 40 CFR Part 130. The
law requires that jurisdictions establish priority rankings and develop TMDLs for waters on the
lists of impaired waters (40 CFR 130.7).
A TMDL specifies the maximum amount of a pollutant that a waterbody can receive and still
meet applicable WQS. A mathematical definition of a TMDL is written as the sum of the
individual wasteload allocations (WLAs) for point sources, the load allocation (LAs) for
nonpoint sources and natural background, and a margin of safety (MOS)[CWA section
303(d)(l)(C)]:
TMDL = IWLA + ILA + MOS
where
WLA = \vasie\oad avocation, or the portion of the TMDL allocated to existing and/or
future point sources.
LA = load allocation, or the portion of the TMDL attributed to existing and/or future
nonpoint sources and natural background.
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Chesapeake Bay TMDL
MOS = margin of safety, or the portion of the TMDL that accounts for any lack of
knowledge concerning the relationship between effluent limitations and water
quality, such as uncertainty about the relationship between pollutant loads and
receiving water quality, which can be provided implicitly by applying
conservative analytical assumptions or explicitly by reserving a portion of loading
capacity.
The process of calculating and documenting a TMDL involves a number of tasks and—
especially for a large, complex, and multijurisdictional waterbody with multiple impairments—
can require substantial effort and resources. Major tasks involved in the TMDL development
process include the following:
• Characterizing the impaired waterbody and its watershed
• Identifying and inventorying the relevant pollutant source sectors
• Applying the appropriate WQS
• Calculating the loading capacity using appropriate modeling analyses to link pollutant
loads to water quality
• Identifying the required source allocations
The Bay TMDL report presents the results of numerous analyses and model simulations
designed to calculate the Bay and its tidal tributaries and embayments' pollutant loading capacity
and documents the informational elements described above. Because the Chesapeake Bay
watershed is so large, and the analysis required for developing the Bay TMDL so extensive, the
Chesapeake Bay TMDL and its supporting documentation consists of this report and additional
supporting materials in the numerous appendices referenced throughout the report. The Bay
TMDL is also supported by an extensive list of significant documents (Appendix B).
1.2 HISTORY OF THE CHESAPEAKE BAY TMDL
The Chesapeake Bay watershed has been inhabited for thousands of years, but the population
started to increase significantly with the arrival of European settlers in the 1600s. Settlers began
clearing forests for timber and to make room for expanding agricultural activities, increasing soil
erosion and nutrient delivery to the Bay and its tributaries (Curtin et al. 2001; Rountree et al.
2007). As early as 1900, the oyster population began to decline. Throughout the 20th century,
urban development and agricultural activities increased throughout the watershed. In the late
1970s, Maryland Senator Charles Mathias sponsored a congressionally funded, 5-year study to
analyze the rapid loss of aquatic life that was affecting the Bay. That study identified excess
nitrogen and phosphorus pollution as the main source of the Bay's degradation (USEPA 1982,
1983a, 1983b, 1983c, 1983d).
1.2.1 Regulatory and Management Initiatives
In response to the Bay's decline, various regulatory and management initiatives have been
undertaken aimed at Bay restoration, ranging from cooperative agreements among surrounding
jurisdictions to new regulatory programs and policies. Through the years, the agreements and
alliances have become more formalized and inclusive to address the multitude of factors
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Chesapeake Bay TMDL
contributing to the deterioration in Chesapeake Bay water quality. The following paragraphs
outline the major policy, legislative, and programmatic events that have led to the development
of the Bay TMDL, including the management agreements and statutory and regulatory
requirements that form the underpinning of the Bay TMDL.
1983 Chesapeake Bay Agreement
In 1983 the governors of Maryland, Virginia, and Pennsylvania; the mayor of the District of
Columbia; the chairman of the Chesapeake Bay Commission; and EPA's Administrator signed
the first Chesapeake Bay Agreement. In that agreement, the signatories acknowledged the
decline in living resources of the Chesapeake Bay and agreed to establish the Chesapeake
Executive Council (CEC) to "assess and oversee the implementation of coordinated plans to
improve and protect the water quality and living resources of the Chesapeake Bay estuarine
systems" (Chesapeake Bay Partnership 1983).
1987 Chesapeake Bay Agreement
Faced with the need to take a more comprehensive and coordinated approach to restoring water
quality and living resources of the Chesapeake Bay, the signatories to the 1983 agreement
entered into the 1987 Chesapeake Bay Agreement (CEC 1987). The 1987 Chesapeake Bay
Agreement set priority goals and commitments, of which a key goal was to "reduce and control
point and nonpoint sources of pollution to attain the water quality condition necessary to support
the living resources of the Bay." To achieve that goal, signatories to the 1987 Bay Agreement
committed to reduce the controllable nitrogen and phosphorus loads delivered to the mainstem of
the Chesapeake Bay by 40 percent by 2000 and to develop a Bay-wide implementation strategy
to achieve those reductions (CEC 1987).
CWA Section 117 and the Chesapeake Bay Program (CBP)
In the 1987 amendments to the CWA, Congress—in section 117—authorized the formation and
funding of the Chesapeake Bay Program (CBP) within EPA Region 3. Congress directed the
CBP to collect and disseminate information related to the environmental quality of the Bay, to
"coordinate state and federal efforts to improve Bay water quality, to evaluate sediment impacts
on the Bay, and to determine the impact of natural and human-induced environmental changes
on the living resources of the Bay."
1991 Reevaluation
A 199I reevaluation of progress made toward achievement of the 1987 Bay Agreement's 40
percent nutrient reduction goal led to a detailed quantification of the original narrative goal. Each
major river basin by jurisdiction received a "tributary nutrient load allocation" as a "40%
controllable load reduction" for both nitrogen and phosphorus as the principal outcome of the
reevaluation (Secretary Robert Perciasepe 1992). The 1991 reevaluation also introduced several
concepts still applicable in the Bay TMDL: tributary strategies (WIPs), limit of technology
(everything by everyone everywhere or E3 scenario), recognition of air deposition (air load
allocation to tidal surface waters), and geographic-based allocations (relative effectiveness-based
allocation methodology).
Clean Water Act section 117(33 United States Code [U.S.C.I I2671
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1992 Amendments to the Chesapeake Bay Agreement
The 1991 reevaluation led to several amendments to the 1987 Chesapeake Bay Agreement in
1992. including an increased focus on the importance of the tributaries in the Bay's restoration.
The parties to the 1987 Chesapeake Bay Agreement were to begin by 1993 to develop and
implement tributary-specific strategies to meet mainstem nutrient reduction goals, to improve
water quality, and to restore living resources to the mainstem and tributaries (CEC 1992). The
amendments also established a goal of expanding the distribution of submerged aquatic
vegetation (SAV) as an initial measure of progress toward the water quality and living resource
goals of the 1987 Agreement.
1997 Reevaluation
In 1997 the CBP conducted a year-long evaluation to assess what progress had been made
toward the goal set in the 1987 Chesapeake Bay Agreement of a 40 percent reduction by 2000 in
nitrogen and phosphorus delivered to the Bay (CEC 1997). The 1997 reevaluation found that
between 1985 and 1996 phosphorus loads delivered to the Bay declined by 6 million pounds
annually, and nitrogen loads delivered to the Bay declined by 29 million pounds annually. By
1996 phosphorus loads from wastewater dischargers had been reduced by 51 percent in the
participating jurisdictions as a result of implementing effluent standards, upgrading wastewater
treatment plants, and banning phosphate laundry detergents. Wastewater nitrogen loads were
reduced by 15 percent by implementing biological nutrient removal at some major municipal
wastewater treatment facilities and by upgrading certain industrial wastewater treatment
facilities. Implementation of nutrient reduction best management practices (BMPs) reduced
nonpoint source loadings of nitrogen and phosphorus to the Bay by 7 and 9 percent, respectively.
There was no clear trend in Bay dissolved oxygen (DO) levels, however. Although progress was
made, the 1997 reevaluation report stated, "we must accelerate our efforts to close the gap on the
year 2000 goal, maintain those reduced loading levels into the future and if necessary adjust the
nutrient goals to help us achieve the water quality improvements needed to sustain living
resources in the Bay" (CBP 1997).
1999 Integration of Cooperative and Statutory Programs
In September 1999. senior water quality program managers representing the Bay watershed
jurisdictions and EPA outlined the Process for Integrating the Cooperative and Statutory
Programs of the Chesapeake Bay and its Tributaries—Continuing the Watershed Partnership to
Restore the Chesapeake Bay (CBP 1999). That consensus document laid the groundwork for the
water quality goals and commitments within the Chesapeake 2000 Agreement. A decade in
advance, it set the partnership on a course that culminated in the Bay TMDL.
Chesapeake 2000 Agreement
In June 2000 the governors of Maryland, Virginia, and Pennsylvania; the mayor of the District of
Columbia: the Administrator of EPA; and the chairman of the Chesapeake Bay Commission
signed the Chesapeake 2000 Agreement (CEC 2000). To meet the goal of "achieving and
maintaining the water quality necessary to support the aquatic living resources of the Bay and its
tributaries and to protect human health," the signatories committed to specific actions, including:
"Continue to achieve and maintain the 40 percent nutrient reduction goal agreed to in 1987.
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By 2010. correct nutrient- and sediment-related problems in the Chesapeake Bay and its tidal
tributaries sufficiently to remove the Bay and the tidal portions of its tributaries from the list of
impaired waters under the Clean Water Act. In order to achieve this:
I. By 2001, define the water quality conditions necessary to protect aquatic living
resources and then assign load reductions for nitrogen and phosphorus to each
major tributary;
2. By 2001, using a process parallel to that established for nutrients, determine the
sediment load reductions necessary to achieve the water quality conditions that
protect aquatic living resources, and assign load reductions for sediment to each
major tributary:
3. By 2002. complete a public process to develop and begin implementation of
revised Tributary Strategies to achieve and maintain the assigned loading goals;
4. By 2003, jurisdictions with tidal waters use their best efforts to adopt new or
revised WQS consistent with the defined water quality conditions. Once
adopted by the jurisdictions, EPA will expeditiously review the new or revised
standards, which are used as the basis for removing the Bay and its tidal rivers
from the list of impaired waters; and
5. By 2003, work with the Susquehanna River Basin Commission and others to
adopt and begin implementing strategies that prevent the loss of the sediment
retention capabilities of the lower Susquehanna River dams."
2000 Six-Jurisdiction Memorandum of Understanding
In the fall of 2000, EPA, Delaware, the District of Columbia, Maryland, New York,
Pennsylvania, and Virginia signed a Memorandum of Understanding (MOD) (Chesapeake Bay
Watershed Partners 2000), with West Virginia joining as a signatory in June 2002, agreeing to
the following:
• Work cooperatively to achieve the nutrient and sediment reduction targets necessary to
achieve the goals of a clean Chesapeake Bay by 2010, thereby allowing the Chesapeake
Bay and its tidal tributaries to be removed from the list of impaired waters.
• Provide for an inclusive, open and comprehensive public participation process.
• Collaborate on the development and use of innovative measures such as effluent trading,
cooperative implementation mechanisms, and expanded interstate agreements to achieve
the necessary reductions.
The signatories also agreed to report annually on progress toward achieving the goals of the
agreement.
2003 Nutrient and Sediment Cap Load Allocations
In 2003 EPA and its seven watershed jurisdictional partners established nitrogen, phosphorus,
and sediment cap loads based on Bay water quality model projections of attainment of the then
EPA-proposed dissolved oxygen water quality criteria under long-term average hydrologic
conditions (Secretary Tayloe Murphy 2003). Reaching those cap loads was expected to eliminate
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the summer no-oxygen conditions in the deep waters of the Bay and excessive algal blooms
throughout the Bay, tidal tributaries and embayments (USEPA 2003c).
EPA and its watershed jurisdiction partners allocated the nitrogen and phosphorus cap loads
among the major river basins by jurisdiction. Those jurisdictions with the highest impact on Bay
water quality were assigned the highest nutrient reductions, while jurisdictions without tidal
waters received less stringent reductions because they would not realize a direct benefit from the
improved water quality conditions in the Bay (USEPA 2003c). Sediment allocations were based
on the phosphorus-equivalent allocations to each major river basin by jurisdiction (USEPA
2003c).
Although not original signatories of the Chesapeake 2000 Agreement, New York, Delaware, and
West Virginia signed on as partners in implementing the cap loads; thus, all seven Bay watershed
jurisdictions were assigned allocations (Chesapeake Bay Watershed Partners 2000; USEPA
2003c). The final total basinwide cap loads agreed to by EPA and the seven watershed
jurisdictions were 175 million pounds of nitrogen per year and 12.8 million pounds of
phosphorus per year delivered to the tidal waters of the Bay (USEPA 2003c). The basinwide
upland sediment cap load was 4.15 million tons per year (USEPA 2003c).
2004-2006 Tributary Strategies
To achieve the nitrogen, phosphorus, and sediment cap loads, the seven watershed jurisdictions
developed what became known as the Chesapeake Bay Tributary Strategies (Table 1-1)
(Secretary Tayloe Murphy 2003). The tributary strategies outlined river basin-specific
implementation activities to reduce nitrogen, phosphorus, and sediment pollutant loads from
point and nonpoint sources sufficient to remove the Chesapeake Bay and its tidal tributaries and
embaymenls from the Bay jurisdictions' respective impaired waters lists. Many of the policies
and procedures used in developing the Chesapeake Bay TMDL originated with the development
of the 2003 nutrient and sediment cap loads and subsequent development of tributary strategies.
Table 1-1. URLs for accessing the seven Chesapeake Bay watershed jurisdictions'
tributary strategies
Jurisdiction
Delaware
District of
Columbia
Maryland
New York
Pennsylvania
Virginia
West Virginia
Tributary strategy URL link
httD://wwwchesaDeakebav.net/watershedimDlementationDlantools.asDx?menuitem=52044
httD://www.chesaDeakebav.net/watershedimDlementationDlantools.asDx?menuitem=52044
htto //www dnr.state.md.us/bav/tribstrat/irriDlementation olan.html
httD://www.dec.nv.aov/docs/water odf/cbavstratfinal.Ddf
httD://www.chesaDeakebav.net/watershedimDlementationDlantools.asDx?menuitem=52044
httD://www.chesaDeakebav.net/watershedimDlementationDlantools.asDx?menuitem=52044
httD://www.wvca.us/bav/files/bav documents/8 9657 VW Potomac Tributary Strateav F
INAL from web Ddf
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Chesapeake Bay TMDL
2004-2005 Jurisdiction Adoption of Chesapeake Bay Water Quality Standards
In continued efforts to coordinate activities to address nitrogen, phosphorus, and sediment-based
pollution in the Bay, the tidal jurisdictions of Maryland, Virginia. Delaware, and the District of
Columbia adopted into their respective WQS regulations the HPA-published C'hesapeake Bay
water quality criteria for dissolved oxygen, water clarity, SAV, and chlorophyll ti. along with
criteria attainment assessment procedures and refined tidal water designated uses (for details, see
Section 3) (USEPA 2003a. 2003d). EPA approved those four jurisdictions' WQS regulations
modifications pursuant to CWA section 303(c).
2007 Reevaluation
Secretary Tayloe Murphy's 2003 memorandum summarized the comprehensive set of
agreements made by Bay watershed partners with regard to cap loads for nitrogen, phosphorus,
and sediment; new Bay-wide and local SAV restoration goals; and a commitment to reevaluate
the allocations in 2007 (Secretary Tayloe Murphy 2003). The initiation of that revaluation at a
partnership sponsored workshop in September 2005 laid the institutional groundwork for the
collaborative work on the Bay TMDL (Chesapeake Bay Reevaluation Steering Committee
2005).
EPA and the seven watershed jurisdictions reevaluated the nutrient and sediment cap loads in
2007, in response to the four Bay jurisdictions revising their WQS regulations for the
Chesapeake Bay, its tidal tributaries and embayments in 2004-2005 (Secretary Tayloe Murphy
2003). The 2007 revaluation found that sufficient progress had not been made toward
improving water quality to a level that indicated the mainstem Chesapeake Bay and its tidal
tributaries and embayments were no longer impaired by nitrogen, phosphorus, and sediment
pollution (Chesapeake Bay Reevaluation Steering Committee 2005).
1.2.2 Partnership Commitment to Develop the Chesapeake Bay TMDL
Throughout the Bay TMDL development process, EPA has worked in close and open partnership
with all seven watershed jurisdictions, sharing decision making with the jurisdictions via the
CBP structure described in Section 1.3. While EPA established the Bay TMDL, the seven
watershed jurisdictions were essential partners in the initiative, providing critical input and
participating in deliberations and making key decisions affecting the development process. The
seven Bay watershed jurisdictions and EPA had been building the foundation for the Chesapeake
Bay TMDL since signing the Chesapeake 2000 Agreement, which laid out the steps necessary to
put in place an appropriate framework for a future Bay TMDL, including consistent
jurisdictional Chesapeake Bay WQS (CEC 2000).
From the September 2005 reevaluation workshop to the publication of the Bay TMDL in
December 2010, the seven watershed jurisdictions were actively involved in developing the Bay
TMDL through participation in the CBP's Principals' Staff Committee (PSC), Water Quality
Goal Implementation Team (WQG1T), and other decision-making committees, teams, and
technical workgroups (see Section 1.3.1). The full records of the meetings and conference calls
of those committees, teams, and workgroups are accessible via the Internet—see Appendix C.
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Chesapeake Bay TMDL
At the October 1, 2007 meeting of the PSC, the seven watershed jurisdictions and EPA reached
consensus that EPA would establish the Bay TMDL on behalf of the seven jurisdictions with a
target date of 2025 when all necessary pollution control measures would be in place (CBP PSC
2007). Consensus within the Principals' Staff Committee means that all parties present have
either agreed on this as a course of action and/or that no party objected to it. Table 1-2
summarizes that and the other Bay TMDL-relevant consensus agreements reached by the
partners during that meeting.
Table 1-2. Summary of Chesapeake Bay TMDL relevant actions agreed to by the CBP's
Principals' Staff Committee during its October 1, 2007, meeting
The Bay watershed TMDLs will be developed jointly between the six Bay watershed states, the
District, and EPA and then established by EPA.
The Water Quality Steering Committee (WQSC) will draft nutrient and sediment cap load
allocations by tributary basin by jurisdiction, and the PSC will formally adopt these allocations.
The watershed states and the District would have responsibility for further assigning loads —
WLAs and LAs—to sources consistent with EPA regulations and guidance.
These state/District suballocations (WLA/LA) would become part of the overall Bay watershed
TMDLs report.
The final publication would contain all the required documentation supporting the EPA Bay
watershed TMDLs in a single, integrated publication with extensive appendices.
EPA will provide the technical resources/analyses required to support development of the Bay
watershed TMDLs through the CBP Office staff and EPA-funded contractor support.
The Bay watershed TMDLs must be completed and established by EPA no later than May 1,
2011.
The CBP partners will engage stakeholders and the public in a more extensive structured
dialogue about the tributary strategy implementation challenges before us.
The CBP partners will focus on getting the programs in place by 2010 that we believe are
required to achieve our water quality goals.
The CBP partnership's public announcement of initiation of work on the Bay watershed TMDLs
will occur following the states' submission and EPA approval of the 2008 303(d) lists in the spring
2008 time frame.
Eight principles will guide the reevaluation efforts by the WQSC and its workgroups (see
Attachment A for more detailed version):
o Shared urgency to restore the Bay;
o Clear communication and common message;
o Focus and accelerate implementation (do no harm);
o Engage the public about the implementation challenge;
o Legal obligations will be met;
o Improving and applying the latest science;
o Flexibility of the sub-allocations within the major basins; and
o Keep healthy waters healthy.
The WQSC will proceed forward with the responsibility for carrying out the necessary preparation
work following these eight guiding principles.
The state/EPA Reevaluation Technical Workgroup (RTWG) will be reconvened and operate
under the direction of the WQSC.
The RTWG was charged with responsibility for resolving the existing technical issues in light of
the desire to accelerate implementation at all scales. The WQSC will convene a parallel
Implementation Workgroup and charge this group with the responsibility for ensuring that the
reevaluation and TMDL development process results in acceleration of ongoing tributary strategy
implementation.
Source: CBP PSC 2007
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Chesapeake Bay TMDL
1.2.3 President's Chesapeake Bay Executive Order
On May 12, 2009, President Barack Obama issued the Chesapeake Bay Protection and
Restoration Executive Order 13508, which calls Tor the federal government to lead a renewed
effort to restore and protect the Chesapeake Bay and its watershed. Critical among its directives
were:
• Establish a Federal Leadership Committee to oversee the development and coordination of
reporting, data management and other activities by agencies involved in Bay restoration.
• Require involved agencies to prepare and submit reports with recommendations on a wide
range of Bay issues (EPA-HQ-OW-2009-0761; FRL-8978-8).
• Require the Federal Leadership Committee to develop a Strategy for Protecting and
Restoring the Chesapeake Bay by May 2010 (http://executiveorder.chesapeakebav.net/').
• Require the Federal Leadership Committee to publish an annual Chesapeake Bay Action
Plan describing how federal funding proposed in the President's budget will be used to
protect and restore the Chesapeake Bay during the upcoming fiscal year.
• Require federal agencies to consult extensively with Bay watershed jurisdictions in
preparing their reports.
Pursuant to the Executive Order, on May 12, 2010, the Federal Leadership Committee—led by
the EPA Administrator and secretaries from the Departments of Agriculture, Commerce,
Defense, Homeland Security, Interior, Transportation, and others—issued its coordinated
strategy for restoring the Chesapeake Bay (FLCCB 2010). That strategy sets measurable goals
for improving environmental conditions in the Bay for the following:
• Clean water
• Habitat
• Fish and wildlife
• Land and public access
Other supporting strategies address citizen stewardship, climate change, science, and
implementation and accountability. A key element of the approach for meeting water quality
goals was the development of this TMDL for the Chesapeake Bay (FLCCB 2010).
Parallel to the issuance of the Executive Order, the jurisdictions and the federal government
committed to implement all necessary measures for restoring water quality in the Bay by 2025
and to meet specific milestones every 2 years (FRL-8955-4; Clean Water Act section 303(d):
Preliminary Notice of Total Maximum Daily Load (TMDL) Development for the Chesapeake
Bay). To that end, EPA is developing an accountability framework to guide the overall
restoration effort and to link it to implementation of the Chesapeake Bay TMDL. The
accountability framework, which is discussed in more detail in Section 7, includes four elements:
• Watershed Implementation Plans (WIPs)
• Two-year milestones to demonstrate restoration progress
• EPA's commitment to track and assess progress
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Chesapeake BayTMDL
• Federal actions if the Bay watershed jurisdictions fail to meet expectations such as
developing sufficient WIPs, effectively implementing their WIPs, and/or fulfilling their 2-
year milestones
1.3 BAY TMDL PROCESS, PARTNER COORDINATION AND
RESPONSIBILITIES
EPA Region 3 is the lead federal office responsible for developing the Chesapeake Bay TMDL,
with the Water Protection Division (WPD) having the lead responsibility within the Regional
Office. In developing this TMDL WPD coordinated efforts with the Chesapeake Bay Program
Office. Air Protection Division, Office of Regional Counsel, Office of State and Congressional
Relations, Office of Public Affairs, and Office of the Regional Administrator (all within EPA
Region 3), EPA Region 2 (Division of Environmental Planning and Restoration and Office of the
Regional Administrator), and EPA Headquarters (Office of Water, Office of General Counsel.
Office of Air and Radiation, and Office of the Administrator). Throughout the Bay TMDL
development process, EPA worked in close and open partnership with all seven watershed
jurisdictions, numerous federal agency partners, and a diverse array of other partners and
stakeholders through the CBP partnership. This section describes the different elements of the
CBP organizational structure and provides additional descriptions of the roles and
responsibilities of the various entities and stakeholders involved in developing the Chesapeake
BayTMDL.
1.3.1 CBP Partnership and Organizational Structure
The CBP is a unique regional partnership that includes Maryland, Pennsylvania, Virginia, the
District of Columbia, the Chesapeake Bay Commission. EPA, federal agencies, and participating
advisory groups. The headwater states of Delaware. New York, and West Virginia participate as
full partners on issues related to water quality. Each of the CBP partners agrees to use its own
resources to implement projects and activities that advance Bay and watershed restoration.
The partnership defines its collective actions through formal, voluntary agreements and provides
general policy direction through consensus documents, typically called directives. The CBP
works through a series of Goal Implementation Teams with oversight provided by the CBP's
Management Board. Extensive documentation of the CBP structure and governance is provided
in Chesapeake Bay Program Governance—Managing the Partnership for a Restored and
Protected Watershed and Bay (CBP 2009). Figure l-l shows the CBP organizational chart.
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Chesapeake Bay TMDL
CBP Organizational Structure and Leadership o».2
-------
Chesapeake Bay TMDL
Principals' Staff Committee
The Principals' Stall Committee (PSC) provided policy and programmatic direction to the
Management Board on the development and adoption of the Chesapeake Bay nutrient and
sediment targets and allocations for the Bay TMDL (Figure 1-1). The PSC is composed of
cabinet-level representatives from each ot the seven watershed jurisdictions, EPA Region 3's
Regional Administrator, senior federal agency executives, the Chesapeake Bay Commission
executive director, and the director of the CBP Office. The Regional Administrator of EPA
Region 3 currently chairs the PSC. The Citizens, Local Governments, and the Scientific and
Technical advisory committees all advise the PSC.
Management Board
PSC members provided policy and program direction to the Management Board which, in turn,
provided strategic planning, priority setting, and operational guidance and direction to the Water
Quality Goal Implementation Team (WQGIT) during the development of the Bay TMDL
(Figure 1-1). The Management Board is composed of senior policy representatives from the
seven watershed jurisdictions, the Chesapeake Bay Commission, the nine core federal agency
partners,2 and the chairs of the Citizens, Local Governments, and the Scientific and Technical
advisory committees. The Management Board directs and coordinates the efforts of the six Goal
Implementation Teams and Action Teams. The director of the CBP Office chairs the
Management Board, and the CBP Office provides for the staff to support the work of all the Goal
Implementation Teams and workgroups. Staffing for the three advisory committees is supported
by EPA through cooperative agreements with nonprofit organizations.
Water Quality Goal Implementation Team
The WQGIT's purpose is to support efforts to reduce and cap the nitrogen, phosphorus, and
sediment loads entering the Bay and to ensure that such reductions are maintained over time. It is
composed of the members of the former Water Quality Steering Committee and the former
Nutrient Subcommittee. The WQGIT provided advice and guidance to EPA related to the draft
target loads and allocations before they were brought to the PSC. The WQGIT consists of senior
water program managers from each of the seven Bay watershed jurisdictions, EPA Headquarters
and Regions 2 and 3, the Chesapeake Bay Commission, the Susquehanna River Basin
Commission, and the Interstate Commission on the Potomac River Basin. The WQGIT provided
technical direction to the Watershed Technical, Agriculture, Forestry, Wastewatcr Treatment,
Sediment, and Urban Stormwater workgroups.
Watershed Technical Workgroup
The Watershed Technical Workgroup was created to provide a forum for communication among
the Bay watershed jurisdictions and other CBP participants on technical issues originally related
to tributary strategy development, tracking and reporting. Members of the Watershed Technical
Workgroup include technical staff and mid-level managers from the seven watershed
jurisdictions, EPA, and point source and environmental stakeholder groups. For the Chesapeake
2 The Natural Resources Conservation Service, U.S. Forest Service, National Oceanic and Atmospheric
Administration, U.S. Geological Survey, National Park Service, U.S. Fish and Wildlife Service, U.S. Army Corps of
Engineers, U.S. Department of Defense, and EPA.
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Chesapeake Bay TMDL
Bay TMDL, the workgroup provided review and oversight in regards to application of the Bay
Watershed Model.
Pollutant Source Workgroups
The Agricultural Workgroup coordinated and evaluated agricultural nutrient and sediment
reduction measures throughout the jurisdictions and resolved issues related to tracking, reporting.
and crediting conservation practices.
The Forestry Workgroup provided information on the effectiveness of different riparian forest
buffer restoration and other forest management practices.
The Wastevvater Treatment Workgroup provided a formal means of communication among
federal agencies, state agencies/jurisdictions, and wastewater treatment facility owner/operators.
The Sediment Workgroup provided technical and policy-related assistance to the CBP partners in
setting the sediment allocations.
The Urban Stormwater Workgroup provided input related to all aspects of stormwater nutrient
and sediment loads and management practices.
Science, Technical Analysis, and Reporting Team—Criteria Assessment Protocols
Workgroup
The Criteria Assessment Protocols Workgroup had the lead responsibility for ensuring
coordinated assessment of all Chesapeake Bay. tidal tributary and embayment waters related to
the four Bay jurisdictions' listing and delisting under CWA section 303(d). The workgroup also
had the lead in developing, reviewing, and recommending to the WQGIT amendments to the
original 2003 Chesapeake Bay water quality criteria published by EPA.
Science, Technical Analysis, and Reporting Team—Modeling Workgroup
The Modeling Workgroup, formerly the Modeling Subcommittee and now under the Science,
Technical Analysis, and Reporting (STAR) team, oversaw the development, calibration,
verification, and management application of the suite of computer-based Bay models that
supported the development of the Bay TMDL. The models allowed managers to estimate the
pollutant load reductions needed to achieve WQS and to assess the potential of different
management scenarios to achieve the needed pollutant load reductions.
Scientific and Technical Advisory Committee
The Scientific and Technical Advisory Committee (STAC) is composed of scientists
representing a diverse range of disciplines from federal agencies and academic institutions in the
seven watershed jurisdictions. STAC provides scientific and technical guidance and independent
scientific peer review to the CBP on measures to restore and protect the Chesapeake Bay. STAC
activities related to the Bay TMDL included independent scientific peer reviews of all the Bay
models (watershed, land change, estuarine water quality, estuarine sediment transport, estuarine
filter feeder), Bay criteria assessment procedures, and land use data, and reviewing and
commenting on the draft Bay TMDL.
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Chesapeake Bay TMDL
Local Governments Advisory Committee
The Local Governments Advisory Committee (LGAC) is a body of locally elected officials
appointed by the governors of Maryland, Pennsylvania, Virginia, and the mayor of the District of
Columbia. The LGAC was established to promote the role of local governments in Bay
restoration efforts and develop strategies that ultimately broaden local government participation
in the CBP. The LGAC was directly involved in developing the Bay TMDL in the following
ways: ensured the direct involvement of local elected officials in the decision-making processes.
helped establish the local Watershed Implementation Plan (WIP) pilots in 2010 (before
development of the Phase II WIPs starting in 2011), and helped inform the thousands of local
governments across the watershed about the Bay TMDL.
Citizen's Advisory Committee
The Citizens Advisory Committee (CAC) provides advice to the CI-XT, the PSC. the Management
Board, and all the Goal Implementation Teams as needed in implementing the Chesapeake Bay
Agreement. The CAC directly assisted the Bay TMDL development process by providing
detailed recommendations on how to engage the nongovernmental components of the larger Bay
watershed community and placing a strong focus on ensuring full accountability during the
development and throughout the long-term implementation of the Bay TMDL.
Appendix A provides the membership lists of all the above described committees, teams, and
workgroups at the time of publication of the Bay TMDL, fully acknowledging their individual
and collective contributions.
1.4 LEGAL FRAMEWORK FOR THE CHESAPEAKE BAY TMDL
1.4.1 What is a TMDL?
As discussed more fully in Section 1.1, a TMDL specifies the maximum amount of a pollutant
that a waterbody can receive and still meet applicable WQS. Allocations to point sources are
called vvasteload allocations or WLAs, while allocations to nonpoint sources are called load
allocations or LAs. A TMDL is the sum of the WLAs (for point sources), LAs (for nonpoint
sources and natural background) (40 CFR 130.2), and a margin of safety (CWA section
303(d)(l)(C)). Section 303(d) requires that TMDLs be established for impaired vvaterbodies "at a
level necessary to implement the applicable [WQS]."3
TMDLs are "primarily informational tools" that "serve as a link in an implementation chain that
includes federally regulated point source controls, state or local plans for point and nonpoint
source pollutant reduction, and assessment of the impact of such measures on water quality, all
to the end of attaining water quality goals for the nation's waters."4 Recognizing a TMDL's role
as a vital link in the implementation chain, federal regulations require that effluent limits in
NPDES permits be "consistent with the assumptions and requirements of any available WLA" in
an approved TMDL.
'33U.S.C. I3l3(d)( I )<(•).
4 Pronsolino v. Nastri, 29! F.3d 1123, 1129 (9th Cir. 2002).
• 40CTR l22.44(d)(lHviiKB).
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Chesapeake Bay TMDL
In addition, before EPA establishes or approves a TMDL that allocates pollutant loads to both
point and nonpoint sources, it determines whether there is reasonable assurance that the nonpoint
source LAs will, in fact, be achieved and WQS will be attained (USEPA 1991b). If the
reductions embodied in LAs are not fully achieved, the collective reductions from point and
nonpoint sources will not result in attainment of the WQS.
The Bay TMDL will be implemented using an accountability framework that includes the
jurisdictions' WIPs, 2-year milestones, EPA's tracking and assessment of restoration progress
and, as necessary, specific federal actions if the Bay jurisdictions do not meet their
commitments. The accountability framework is being established, in part, to demonstrate that the
Bay TMDL is supported by reasonable assurance. The accountability framework is also being
established pursuant to CWA section 11 7(g)( 1). Section I 17(g) of the C WA directs the I-PA
Administrator to "ensure that management plans are developed and implementation is begun...to
achieve and maintain...the nutrient goals of the Chesapeake Bay Agreement for the quantity of
nitrogen and phosphorus entering the Chesapeake Bay and its watershed, (and] the water quality
requirements necessary to restore living resources in the Chesapeake Bay ecosystem."6 In
addition, Executive Order 13508 directs EPA and other federal agencies to build a new
accountability framework that guides local, state, and federal water quality restoration efforts.
The accountability framework is designed to help ensure that the Bay's nitrogen, phosphorus,
and sediment goals, as embodied in the Chesapeake Bay TMDL, are met. While the
accountability framework informs the TMDL, section 303(d) does not require that EPA
"approve" the framework per se, or the jurisdictions' WIPs that constitute part of that
framework.
14.2 Why is EPA establishing this TMDL ?
In 1998, data showed the mainstem and tidal tributary waters of the Chesapeake Bay to be
impaired for aquatic life resources. EPA determined that the mainstem and tidal tributary waters
of the Chesapeake Bay must be placed on Virginia's section 303(d) list. EPA therefore added the
mainstem of the Chesapeake Bay to Virginia's final section 303(d) list. As described in
Section 2, each tidal river, tributary, embayment, and other tidal waterbody that is part of the
Chesapeake Bay TMDL is included on a jurisdiction's section 303(d) list.
EPA established the Chesapeake Bay TMDL pursuant to a number of existing authorities,
including the CWA and its implementing regulations, judicial consent decrees requiring KPA to
address certain impaired Chesapeake Bay and tidal tributary and embayment waters, a settlement
agreement resolving litigation brought by the Chesapeake Bay Foundation, the 2000 Chesapeake
Agreement, and Executive Order 13508. In establishing the Bay TMDL, EPA acted pursuant to
the consensus direction of the Chesapeake Executive Council's PSC and in partnership with each
of the seven Chesapeake Bay watershed jurisdictions.
The CWA provides EPA with ample authority to establish the Chesapeake Bay TMDL. CWA
section 117(g)( 1) provides that "[t]he Administrator, in coordination with other members of the
[CEC], shall ensure that management plans are developed and implementation is begun by
signatories to the Chesapeake Bay Agreement to achieve and maintain [among other things] the
" Clean Water Act section 117(g)( I)(A)-(B), 33 I'.S.C. I267(g)( 1 )(A)-(B).
1-16 December 29, 2010
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Chesapeake Bay TMDL
nutrient goals of the Chesapeake Bay Agreement for the quantity of nitrogen and phosphorus
entering the Chesapeake Bay and its watershed [and] the water quality requirements necessary to
restore living resources in the Chesapeake Bay ecosystem." Because it establishes the Bay and
tidal tributaries' nutrient and sediment loading and allocation targets, the Chesapeake Bay
TMDL, is itself such a "management plan." In addition, the Bay TMDL's loading and allocation
targets both inform and arc informed by a larger set of federal and state management plans being
developed for the Bay, including the Bay watershed jurisdictions' WIPs and the May 2010
Strategy for Protecting, anil Restoring the Chesapeake Bay (FLCCB 2010).
CWA section 303(d) requires jurisdictions to establish and submit TMDLs to EPA for review.
Under certain circumstances, EPA also has the authority to establish TMDLs. The circumstances
of this TMDL do not necessarily identify the outer bounds of EPA's authority. However, where -
as here impaired waters have been identified on jurisdictions' section 303(d) lists for many years,
where the jurisdictions in question decided not to establish their own TMDLs for those waters,
where EPA is establishing a TMDL for those waters at the direction of, and in cooperation with,
the jurisdictions in question, and where those waters are part of an interrelated and interstate water
system like the Chesapeake Bay that is impaired by pollutant loadings from sources in seven
different jurisdictions, CWA section 303(d) authorizes EPA to establish that TMDL7.
On May 12, 2009, President Barack Obama signed Executive Order 13508—Chesapeake Bay
Protection and Restoration. The Executive Order's overarching goal is "to protect and restore
the health, heritage, natural resources, and social and economic value of the Nation's largest
estuarine ecosystem and the natural sustainability of its watershed." The Executive Order says
the federal government "should lead this effort" and acknowledges that progress in restoring the
Bay "will depend on the support of state and local governments." To that end, the Executive
Order directs the lead federal agencies, including EPA, to work in close collaboration with their
state partners. To protect and restore the Chesapeake Bay and its tidal tributaries, the President
directed EPA to "make full use of its authorities under the [CWA]." In establishing the Bay
TMDL, EPA is doing no more—or less—than making full use of its CWA authorities to lead a
collaborative and effective federal and state effort to meet the Bay's nutrient and sediment goals.
A number of consent decrees, memoranda of understanding (MOUs), and settlement agreements
provide additional support for EPA's decision to establish the Chesapeake Bay TMDL
addressing certain waters identified as impaired on the Maryland, Virginia, and the District of
Columbia's 1998 section 303(d) lists and on the Delaware 1996 section 303(d) list. EPA
established the Chesapeake Bay TMDL consistent with those consent decrees, MOUs, and
settlement agreements, described below.
Virginia-EPA Consent Decree
The American Canoe Association, Inc., and the American Littoral Society filed a complaint
against EPA for failing to comply with the CWA. including section 303(d), regarding the TMDL
program in the Commonwealth of Virginia. A consent decree signed in 1999 resolved the
litigation.8 The consent decree includes a 12-year schedule for developing TMDLs for impaired
7 Dioxin Organochlorine (.'enter v Clarke, 57 f.3d 1 517 <0'h Cir. 1995); Scott v City of Hammond. 741 F.2d 992
(7'h Cir. 1984); American Canoe Assn v EPA, 54 F.Supp.2d 621 (E.D.Va. 1999).
* American Canoe Association v !•'.!'A, 98cv979 (June 11, 1999).
1-17 December 29, 2010
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Chesapeake Bay TMDL
segments identified on Virginia's 1998 section 303(d) list. The consent decree requires EPA to
establish TMDLs for those waters, by May 1, 2011, if Virginia fails to do so according to the
established schedule. Virginia has requested that EPA establish TMDLs for the nutrient- and
sediment-impaired tidal portions of the Chesapeake Bay and its tributaries and embayments in
accordance with the Virginia consent decree schedule (CBP PSC 2007). Table 1-3 provides a list
of the Virginia consent decree waters that were addressed by the Chesapeake Bay TMDLs for
nitrogen, phosphorus, and sediment.
Table 1-3. Virginia consent decree (CD) waters impaired for dissolved oxygen (DO) and/or
nutrients addressed by the Chesapeake Bay TMDL
Waterbody Name
Bailey Bay, Bailey Creek - Tidal
Broad Creek
Chesapeake Bay Mainstem
Chesapeake Bay Mainstem
Elizabeth River - Tidal
Hungars Creek
James River - Tidal
King Creek
Mattaponi River - Tidal
Messongo Creek
North Branch Onancock Creek
Pagan River
Pamunkey River - Tidal
Queen Creek
Rappahannock River
Rappahannock River
Rappahannock River
Rappahannock River
Rappahannock River
Thalia Creek
Williams Creek
York River
York River
CD Segment ID
VAP-G03E
VAT-G15E
Narrative a
VACB-R01E
Narrative b
VAT-C14R
Narrative c
VAT-F27E
Narrative d
VAT-C10E
VAT-C11E
VAT-G11E
Narrative e
VAT-F26E
Narrative '
VAP-E25E
VAP-E25E
VAP-E26E
VAP-E26E
VAT-C08E
VAN-A30E
Narrative g
VAT-F27E
Chesapeake Bay Segment ID
JMSTF1
ELIPH, WBEMH.SBEMH,
EBEMH
CB5MH, CB6PH, CB7PH
CB5MH, CB6PH, CB7PH
ELIPH, WBEMH.SBEMH,
EBEMH
CB7PH
JMSTF2, JMSTF1.JMSOH,
JMSMH, JMSPH
YRKPH
MPNTF, MPNOH
POCMH
CB7PH
JMSMH
PMKTF, PMKOH
YRKMH
RPPMH
RPPMH
RPPMH
RPPMH
RPPMH
LYNPH
POTMH
YRKMH, YRKPH
YRKPH
CD Impairment
DO
DO
Nutrients'
DO
Nutrients
DO
Nutrients
DO
Nutrients
DO
DO
DO
Nutrients
DO
Nutrients
Nutrients
DO
Nutrients
DO
DO
DO
Nutrients
DO
Source: American Canoe Association v. EPA, 98cv979 (June 11,1999).
Notes:
a = Chesapeake Bay Mainstem (VACB-R01E) impaired for nutrients
b = Elizabeth River (VAT-G15E) impaired for DO, nutrients
c = James River (VAP-G01 E, VAP-G03E, VAP-G02E, VAP-G04E, VAP-G11 E, and VAP-G15E) impaired for nutrients
d = Mattaponi River (VAP-F24E and VAP-F25E) impaired for nutrients
e = Pamunkey River (VAP-F13E and VAP-F14E) impaired for DO, nutrients
f = Rappahannock River (VAP-E24E) impaired for DO
g = York River (VAT-F26E) impaired for nutrients
1-18
December 29, 2010
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Chesapeake Bay TMDL
District of Columbia-EPA Consent Decree
In 1998 Kingman Park Civic Association and others filed a similar suit against EPA." The
lawsuit was settled through the entry of a consent decree requiring I:PA to, among other things.
establish TMDLs for the District of Columbia's portions of the tidal Potomac and tidal Anacostia
rivers if not established by the District of Columbia by a certain date.
The impairment of the District of Columbia's portion of the upper tidal Potomac River by low
pH is directly related to the Chesapeake Bay water quality impairments because the low pi I is a
result of excess nutrients causing algal blooms in the tidal river. Establishing a tidal Potomac
River pH TMDL is directly linked to establishing the Chesapeake Bay TMDL because of their
common impairing pollutants (nitrogen and phosphorus) and the hydrologic connection between
the District's portion of the tidal Potomac River and the Chesapeake Bay. EPA and the Kingman
Park plaintiffs jointly sought, and received on February 12, 2008. a formal extension of the
District of Columbia TMDL Consent Decree so that EPA could complete the Potomac River pH
TMDL on the same schedule as the Chesapeake Bay TMDL.1" The District of Columbia
requested that EPA establish the pH TMDL for the District's portion of the tidal Potomac River
(CBP PSC 2007). Table 1-4 provides a list of the District's consent decree waters that were
addressed by the Chesapeake Bay TMDLs for nitrogen, phosphorus, and sediment.
In addition, Anacostia Riverkeeper and Friends of the Earth filed suit against EPA challenging
more than 300 TMDLs for the District of Columbia, including the Anacostia River TMDLs,
because the TMDLs were not expressed as daily loads. On May 25, 2010, the District Court for
the District of Columbia ordered the vacatur of the District of Columbia's TMDL for pH for the
Washington Ship Channel, with a stay of vacatur until May 31, 2011." With publication of the
Bay TMDL, the Washington Ship Channel pH impairment has been addressed and the pH
TMDL for the Ship Channel approved by EPA on December 15, 2004 has been superseded.
Table 1-4. District of Columbia consent decree (CD) waters impaired for pH addressed by
the Chesapeake Bay TMDL
Waterbody Name
Washington Ship Channel
Middle Potomac River
CD Segment ID
DCPWC04E_00
DCPMSOOE
Chesapeake Bay Segment ID
POTTF_DC
POTTF_DC
CD Impairment
PH
PH
Source: Kingman Park Civic Association v EPA, 98cv00758 (June 13, 2000).
Delaware-EPA Consent Decree
In 1996 the American Littoral Society and the Sierra Club filed a suit against EPA to ensure that
TMDLs were developed for waters on Delaware's 1996 section 303(d) list, one of which is a
tidal Bay segment (Upper Nanticoke River). The parties entered into a consent decree resolving
the lawsuit.12 The consent decree required EPA to establish TMDLs if Delaware failed to do so
within the 10-year TMDL development schedule. Although Delaware established TMDLs for the
" Kingman Park ('Me Association v EPA, ')8cv00758 (June 13, 2000).
" Kinsman Park Civic Association v. EPA. 98cv00758 (Order February 12, 2008).
1' Anacostia Riverkeeper el at v Jackson. 1:200(>cv00098 (D.DC)( Mem. and Order May 25, 2010)
*- American Littoral Society, el til v EPA. el al., 96cv59l (D.Del. 1997).
1-19 December 29, 2010
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Chesapeake Bay TMDL
one listed tidal Bay segment (DE DNREC 1998), the TMDLs were established to meet prior
WQS and are insufficient to attain Chesapeake Bay WQS.
Maryland-EPA MOD
In 1998 Maryland and EPA Region 3 entered into an MOU that, among other things, established
a 10-year schedule for addressing waters on Maryland's 1998 section 303(d) list, with
completion by 2008 (MDE 1998). Because of funding constraints, the complexity of some
TMDLs, and limited staff resources, Maryland determined that it would not be able to address all
1998 listed waters by 2008. Further, the Chesapeake 2000 Agreement established a goal of
meeting water quality standards in the Chesapeake Bay by 2010 (CEC 2000). Many of the waters
on Maryland's 1998 section 303(d) list were open waters of the Bay or tidal tributaries and
embayments to the Bay. Maryland determined that developing TMDLs for those tidal waters
before the deadline established by the MOU, as would be required under the schedule established
in 1998, "would undermine the spirit of the agreement" because of a lack of integration between
the CBP partnership and Maryland efforts (MDE 2004). Therefore, Maryland decided to
postpone development of TMDLs for Maryland's listed Chesapeake Bay and its tidal tributary
and embayment waters until the two programs could coordinate efforts.
In September 2004. Maryland and EPA Region 3 entered into a revised MOU that extended the
schedule for TMDL development to 13 years (by 2011) (MDE 2004). Although neither
Maryland nor EPA is under a consent decree for establishing TMDLs for Maryland waters, the
state has requested that EPA develop the TMDLs for the Maryland portion of the Chesapeake
Bay and tidal tributaries and embayments impaired by excess nitrogen, phosphorus, and
sediment as recognized in the MOU between Maryland and EPA (CBP PSC 2007).
Chesapeake Bay Foundation Settlement Agreement
In January 2009, the Chesapeake Bay Foundation and others filed suit against EPA in U.S.
District Court for the District of Columbia (1:09-cv-00005-CKK) alleging, among other things.
that EPA had failed to carry out nondiscretionary duties under CWA section 117(g) designed to
restore and preserve the Chesapeake Bay. In May 2010, EPA signed a settlement agreement with
the plaintiffs promising to take a number of actions to restore and preserve the Bay. In particular,
EPA promised that by December 31, 2010, it would establish a TMDL for those segments of the
Chesapeake Bay impaired by nitrogen, phosphorus, and sediment. EPA is establishing this
TMDL, in part, to meet that commitment.
1-20 December 29, 2010
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Chesapeake Bay TMDL
SECTION 2. WATERSHED AND IMPAIRMENT
DESCRIPTION
This section provides a general description of the watershed and the impairments addressed in
the Chesapeake Bay TMDL. Section 2.1 provides a description of the basic history, geography,
land uses, and recent development patterns and trends. Section 2.2 presents the scope of the Bay
TMDL including the parameters of concern, the specific impairment listings addressed, and the
Bay TMDL segmentation.
2.1 GENERAL WATERSHED SETTING
The Chesapeake Bay watershed includes parts of six states—Delaware, Maryland, New York,
Pennsylvania, Virginia, and West Virginia—and the entire District of Columbia (collectively, the
jurisdictions). The Chesapeake Bay proper is approximately 200 miles long, stretching from
Havre de Grace, Maryland, to Norfolk, Virginia. It varies in width from about 3.4 miles near
Aberdeen, Maryland, to 35 miles near the mouth of the Potomac River. The easternmost
boundary of the Chesapeake Bay with the Atlantic Ocean is represented by a line between Cape
Charles and Cape Henry. Including its tidal tributaries and embayments, the Chesapeake Bay
encompasses approximately 11,684 miles of shoreline, a length longer than the entire West Coast
of the United States.
About half of the Bay's water volume consists of saltwater from the Atlantic Ocean. The other
half is freshwater that drains into the Bay from its 64,000-square-mile watershed (Figure 2-1).
Ninety percent of the freshwater is delivered from five major rivers: the Susquehanna (which is
responsible for about 50 percent), Potomac, James, Rappahannock, and York rivers. In all, the
watershed contains more than 10,000 streams and rivers that eventually flow into the Bay.
Runoff from the Bay's enormous watershed flows into an estuary with a surface area of 4,500
square miles resulting in a land-to-water ratio of 14 to I. That large ratio is one of the key factors
in explaining why the drainage area has such a significant influence on water quality in the Bay.
Although the Chesapeake Bay is entirely within the Atlantic Coastal Plain, its watershed includes
parts of the Piedmont and Appalachian provinces. The waters that flow into the Bay have
different chemical characteristics, depending on the geology from which they originate
(Figure 2-2).
2-1 December 29, 2010
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Chesapeake Bay TMDL
Virginia B
-------
Chesapeake Bay TMDL
Hydrog«omorphlc Raglon*
JIH Appalachian Plateau Carbonate
|B Appalachian Plateau Silidclastlc
Blue Ridge
BH Coeslal Plain Disccted Upland
m Coastal Plain Lowland
HB Coastal Plain Upland
m Mesozioc Lowland
^H Piedmont Carbonate
HH Piedmont Crystallmo
MM Vall«y and Ridga Carbonata
I Valley and Ridye Siliuclastic
Source. USGS WRIR 00-424
Figure 2-2. Hydrogeomorphic regions of the Chesapeake Bay watershed.
2-3
December 29, 2010
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Chesapeake Bay TMDL
The Atlantic Coastal Plain is a flat, lowland area with a maximum elevation of about 300 feet. It
is supported by a bed of crystalline rock, covered with southeasterly dipping wedge-shaped
layers of relatively unconsolidated sand, clay, and gravel. Water passing through the loosely
compacted mixture dissolves many of the minerals. The most soluble elements are iron, calcium,
and magnesium. The coastal plain extends from the edge of the continental shelf, to the east, to a
fall line that ranges from 15 to 90 miles west of the Chesapeake Bay. The fall line, which is the
location where free flowing streams enter tidal waters, forms the boundary between the Piedmont
Plateau and the coastal plain. Waterfalls and rapids clearly mark this line, which is close to
Interstate 95. At the fall line, the elevation rises to 1,100 feet.
The Piedmont Plateau extends from the fall line in the east to the Appalachian Mountains in the
west. The area is divided into two geologically distinct regions by Parrs Ridge, which traverses
Carroll, Howard, and Montgomery counties in Maryland and adjacent counties in Pennsylvania.
Several types of dense, crystalline rock—including slates, schists, marble, and granite—compose
the eastern side of the Piedmont Plateau. That variety results in a very diverse topography. Rocks
of the Piedmont tend to be impermeable, and water from the eastern side is low in calcium and
magnesium salts. The western side of the Piedmont consists of sandstones, shales, and siltstones,
layered over by limestone. The limestone bedrock contributes calcium and magnesium to its
water, making it hard. Waters from the western side of Parrs Ridge flow into the Potomac River,
one of the Chesapeake Bay's largest tributaries.
The Appalachian Province covers the western and northern part of the watershed and is rich in
coal and natural gas deposits. Sandstone, siltstone, shale, and limestone form the bedrock. Water
from that province flows to the Chesapeake Bay mainly via the Susquehanna River.
Earliest evidence of human inhabitants in the Bay watershed is of hunter-gatherers as long as
10,000 years ago. "Native Americans began cultivating crops and settling in villages throughout
the area around 1,000 years ago. European settlement less than 500 hundred years ago began a
period of transformation of forests into farmland, while today many of those lands are
undergoing ^transformations into urban and suburban lands.
Over the past hundreds of years, forest clearing and urban development have resulted in the
following land use breakdown in the watershed: 69 percent wooded/open, 22 percent agriculture,
7 percent developed, and 2 percent open water and extractive (Figure 2-3).
From 1950 through 2008, the Bay watershed's population doubled, increasing from 8.3 million
to 16.8 million. The 8-year period from 2000 to 2008 witnessed population growth of
approximately 7 percent from 15.7 million. Today, nearly 17 million people live in the
watershed. According to census data, the watershed's population is growing by about 157,000
per year. Projections through 2030 are for the population to reach approximately 20 million
(Figure 2-4).
2-4 December 29, 2010
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Chesapeake Bay TMDL
Land Cover(2006)
| Forest
^^| Urban
| | Agriculture
• Other
'. • i.
Source: Irani and Claggett 2010
Figure 2-3. Chesapeake Bay watershed land cover.
2-5
December 29, 2010
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Chesapeake Bay TMDL
Population Projections (Millions)
Source: CBP Office Bay Barometer 2009
Figure 2-4. Reported and projected human population growth In the Chesapeake Bay watershed 1950-2030.
2.2 CHESAPEAKE BAY TMDL SCOPE
The Chesapeake Bay TMDL is the largest, most complex TMDL in the country, covering a
64,000-square-mile area across seven jurisdictions. EPA established a federal TMDL for the tidal
segments of the Chesapeake Bay and its tidal tributaries and embayments that are impaired for
aquatic life uses due to excessive loads of nutrients (nitrogen and phosphorus) and sediment and
listed on the four tidal Bay jurisdictions' respective CWA 2008 section 303(d) lists of impaired
waters. The Bay TMDL also allocates loadings of nitrogen, phosphorus, and sediment to sources
contributing those pollutants in all seven jurisdictions in the Bay watershed—Delaware, the
District of Columbia, Maryland, New York, Pennsylvania, Virginia, and West Virginia.
As described more fully in Section 2.2.1 below, the Chesapeake Bay TMDL addresses only the
restoration of aquatic life uses for the Bay and its tidal tributaries and embayments that are
impaired from excess nitrogen, phosphorus, and sediment pollution. If Bay segments are
impaired for other pollutants, EPA expects that the Bay watershed jurisdictions will develop
separate TMDLs to address those pollutants.
Thousands of previously approved TMDLs have been established to protect local waters across
the Chesapeake Bay watershed. While many addressed other pollutants, some addressed
nitrogen, phosphorus, and/or sediment. For watersheds and waterbodies where both local
TMDLs and Chesapeake Bay TMDLs have already been developed or established for nitrogen,
phosphorus, and sediment, the more stringent of the TMDLs will apply. In some cases, the
reductions required to meet local conditions shown in existing TMDLs may be more stringent
than those needed to meet Bay requirements, and vice versa.
2-6
December 29, 2010
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Chesapeake Bay TMDL
2.2.1 Pollutants of Concern
The pollutants of concern for this TMDL are nutrients—nitrogen and phosphorus—and
sediment. Excessive nitrogen and phosphorus in the Chesapeake Bay and its tidal tributaries
promote a number of undesirable water quality conditions such as excessive algal growth, low
DO, and reduced water clarity (Smith et al. 1992; Kemp et al. 2005). The effect of nitrogen and
phosphorus loads on water quality and living resources can vary considerably by season and
region.
Sediment suspended in the water column reduces the amount of light available to support healthy
and extensive SAV or underwater Bay grass communities (Dennison et al. 1993; Kemp et al.
2004). The relative contribution of suspended sediment and algae that causes poor light
conditions varies with location in the Bay tidal waters (Gallegos 2001).
Sediment also can contain other pollutants. For example, certain bacteria (e.g., Escherichia coli)
often cling to sediment. By reducing sediment, reductions in phosphorus delivered to the Bay
(and possibly other pollutants such as E. coli) also will occur. However, EPA is not providing
allocations for E. coli or other additional pollutants in this TMDL.
If Bay segments are impaired for other pollutants. EPA expects that the Bay watershed
jurisdictions will develop separate TMDLs to address those pollutants. Because of the actions
taken to achieve the Chesapeake Bay TMDL, direct benefits to local water quality conditions in
surface waters throughout the Chesapeake Bay watershed also will occur.
2.2.2 Chesapeake Bay Program Segmentation Scheme
Eor 27 years, the CBP partners have used various versions of a basic segmentation scheme to
organize the collection, analysis, and presentation of environmental data relating to the
Chesapeake Bay. The Chesapeake Bay Program Segmentation Scheme: Revisions, Decisions
and Rationales provides documentation of the spatial segmentation scheme of the Chesapeake
Bay and its tidal tributaries and the later revisions and changes over almost thirty years (USEPA
I983b, 2004b, 2005, 2008a).
Segmentation is the compartmentalization of the estuary into subunits on the basis of selection
criteria (USEPA 2008a). Generally, segments reflect certain unique physical, chemical or
biological characteristics of a portion of a waterbody (e.g., salinity, influence of pollutant
sources, etc.). The 92-segment scheme used in the Chesapeake Bay was derived from the 2004
published 78-segment scheme with additional jurisdictional boundary lines imposed to create 89
segments (USEPA 2004b, 2008a). The scheme includes only the split segments' agreed to by the
CBP partnership for the tidal James and Potomac rivers for a total of 92 segments
(Figure 2-5) (Table 2-1) (USEPA 2008a). The 92 individual watersheds that drain directly into
one of the 92 Chesapeake Bay segments are referred to in this document as Bay segment
watersheds (Figure 2-6).
' A split segment refers to when an established tidal Bay segment was fully bisected for purposes of applying
different water quality criteria specific to two different portions of the same segment—in the case of the James
River, or different assessments of attainment of the same applicable criteria separately from the main river
segment—in the case of the Potomac River.
2-7 December 29, 2010
-------
Chesapeake Bay TMDL
NORTf ELKOH
Chesapeake Bay 303(d) List Segments
>tfp#.
<*\5— •
I
JMO
SUMH
Source: USEPA 2008a
Figure 2-6. The 92 Chesapeake Bay segments.
2-8
December 29, 2010
-------
Chesapeake Bay TMDL
Source: USEPA 2008a
Figure 2-6. The 92 Chesapeake Bay segment watersheds.
2-9
December 29, 2010
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Chesapeake BayTMDL
Table 2-1 lists the eight major river basins draining to the Chesapeake Bay and their associated
Bay segments with information related to each Bay segment's 2008 section 303(d) list status and
whether the Bay segment is addressed by a consent decree or MOU. The 303(d) Integrated
Report listing categories are as follows:
• Category 1—attaining all WQS
• Category 2—attaining some WQS
• Category 3—insufficient information to determine if WQS are attained
• Category 4—impaired or threatened waters that do not need or already have completed a
TMDL
- 4a—TMDL has been completed
- 4b—Other pollution control requirements are reasonably expected to result in the
attainment of the WQS in the near future
- 4c—Impairment is not caused by a pollutant
• Category 5—impaired or threatened water that requires a TMDL
Most Bay segments are listed as category 5 (impaired for most/all designated uses); exceptions
are noted in Table 2-1.
Table 2-1. The Chesapeake Bay 303(d) tidal segments with consent decree (CD)/
memorandum of understanding (MOU) and 303(d) listing status by major river basin and
jurisdiction
Major river
basin
Eastern
Shore
Jurisdiction
MD
MD
DE
MD
MD
VA
MD
MD
MD
MD
MD
MD
MD
MD
VA
MD
MD
Chesapeake Bay
303(d) segment
Big Annemessex River
Bohemia River
C&D Canal, DE
C&D Canal, MD
Eastern Bay
Eastern Lower
Chesapeake Bay
Elk River
Fishing Bay
Honga River
Little Choptank River
Lower Chester River
Lower Choptank River
Lower Nanticoke River
Lower Pocomoke River,
MD
Lower Pocomoke River,
VA
Manokin River
Middle Chester River
Segment ID
BIGMH
BOHOH
C&DOH DE
C&DOH_MD
EASMH
CB7PH
ELKOH
FSBMH
HNGMH
LCHMH
CHSMH
CHOMH2
NANMH
POCMH_MD
POCMH_VA
MANMH
CHSOH
CD/MOU
-
MDMOU
-
MDMOU
MDMOU
VACD
MDMOU
MDMOU
MDMOU
MDMOU
MDMOU
MDMOU
-
MDMOU
VACD
MDMOU
MDMOU
2008 list status'
5
4aforTNandTP
5
5
5
5
5
4aforTNandTP
5
5
5
5
5
5
5
4a for TN and TP
4a for TN and TP
2-10
December 29, 2010
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Chesapeake BayTMDL
Major river
basin
James
Patuxent
Jurisdiction
MD
MD
MD
VA
MD
MD
MD
MD
VA
MD
MD
DE
MD
MD
MD
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
MD
MD
MD
Chesapeake Bay
303(d) segment
Middle Choptank River
Middle Nanticoke River
Middle Pocomoke
River, MD
Middle Pocomoke
River, VA
Mouth of Choptank
River
Northeast River
Sassafras River
Tangier Sound, MD
Tangier Sound, VA
Upper Chester River
Upper Choptank River
Upper Nanticoke River,
DE
Upper Nanticoke River,
MD
Upper Pocomoke River
Wicomico River
Appomattox River
Chickahominy River
Eastern Branch
Elizabeth River
Lafayette River
Lower James River
Lynnhaven River
Middle James River
Mouth of Chesapeake
Bay
Mouth of James River
Mouth to mid-Elizabeth
River
Southern Branch
Elizabeth River
Upper James River -
Lower
Upper James River -
Upper
Western Branch
Elizabeth River
Lower Patuxent River
Middle Patuxent River
Upper Patuxent River
Segment ID
CHOOH
NANOH
POCOH_MD
POCOH_VA
CHOMH1
NORTF
SASOH
TANMH MD
TANMH_VA
CHSTF
CHOTF
NANTFJDE
NANTF_MD
POCTF
WICMH
APPTF
CHKOH
EBEMH
LAFMH
JMSMH
LYNPH
JMSOH
CB8PH
JMSPH
ELIPH
SBEMH
JMSTF1
JMSTF2
WBEMH
PAXMH
PAXOH
PAXTF
CD/MOU
MDMOU
MDMOU
MDMOU
—
MDMOU
MDMOU
MDMOU
MDMOU
-
MDMOU
MDMOU
DECD
finished
MDMOU
MDMOU
MDMOU
-
-
VACD
--
VACD
VACD
VACD
—
VACD
VACD
VACD
VACD
VACD
VACD
MDMOU
MDMOU
MDMOU
2008 list status9
5
5
5
5
5
4a for TN and TP
4a for TP
5
5
4a for TN and TP
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
2-11
December 29, 2010
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Chesapeake Bay TMDL
Major river
basin
Potomac
Rappa-
hannock
Jurisdiction
MD
DC
MD
VA
MD
VA
MD
MD
MD
MD
VA
MD
DC
MD
VA
VA
VA
Chesapeake Bay
303(d) segment
Western Branch
Patuxent River
Anacostia River, DC
Anacostia River, MD
Lower Central
Chesapeake Bay, VA b
Lower Potomac River,
MD
Lower Potomac River,
VA
Mattawoman Creek
Middle Potomac River,
MD - Mainstem
Middle Potomac River,
MD - Nanjemoy Creek
Middle Potomac River,
MD - Port Tobacco
River
Middle Potomac River,
VA
Piscataway Creek
Upper Potomac River,
DC
Upper Potomac River,
MD
Upper Potomac River,
VA
Corrotoman River
.ower Rappahannock
River
Segment ID
WBRTF
ANATF_DC
ANATF_MD
CB5MH_VA b
POTMH_MD
POTMH_VA
MATTF
POTOH1_MD
POTOH2_MD
POTOH2_MD
POTOH_VA
PISTF
POTTF_DC
POTTF_MD
POTTF_VA
CRRMH
RPPMH
CD/MOU
MDMOU
DC CD
MDMOU
VACD
MDMOU
VACD
MDMOU
MDMOU
MDMOU
MDMOU
MDMOU
DC CD
MDMOU
-
VACD
2008 list status9
BOD TMDL
completed for DO
impairments; 4a for
BOD
3 for DO; 4a for
BOD, TN, TP and
TSS
4a for BOD, TN,
TP and TSS
5
5
5
5
5
5
4aforTNandTP
3 for DO in
Migratory
Spawning and
Nursery (MSN); 2
for SAV and DO in
open water
5
3 for DO, 5 for pH
5
3 for DO in
Migratory
Spawning and
Nursery; 2 for SAV
and DO in open
water
5
5
2-12
December 29, 2010
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Chesapeake Bay TMDL
Major river
basin
Susque-
hanna
Western
Shore
York
Jurisdiction
VA
VA
VA
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
VA
VA
VA
VA
VA
VA
VA
VA
Chesapeake Bay
303(d) segment
Middle Rappahannock
River
Upper Rappahannock
River
Western Lower
Chesapeake Bayb
Northern Chesapeake
Bay"
Back River
Bush River
Gunpowder River
Lower Central
Chesapeake Bay, MDb
Magothy River
Middle Central
Chesapeake Bayb
Middle River
Patapsco River
Rhode River
Severn River
South River
Upper Central
Chesapeake Bay"
Upper Chesapeake
Bay"
West River
Lower Martaponi River
Lower Pamunkey River
Lower York River
Middle York River
Mobjack Bay
Piankatank River
Upper Mattaponi River
Upper Pamunkey River
Segment ID
RPPOH
RPPTF
CB6PH"
CB1TF"
BACOH
BSHOH
GUNOH
CB5MH_MDb
MAGMH
CB4MHb
MIDOH
PATMH
RHDMH
SEVMH
SOUMH
CB3MH"
CB20H"
WSTMH
MPNOH
PMKOH
YRKPH
YRKMH
MOBPH
PIAMH
MPNTF
PMKTF
CD/MOU
—
VACD
MDMOU
MDMOU
MDMOU
MDMOU
MDMOU
MDMOU
MDMOU
MDMOU
MDMOU
MDMOU
MDMOU
MDMOU
MDMOU
MDMOU
MDMOU
VACD
VACD
VACD
VACD
-
~
VACD
VACD
2008 list status8
3 for DO in
Migratory
Spawning and
Nursery; 2 for SAV
and DO in open
water
5
5
5
4aforTNandTP
5
5
5
5 "
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
Sources: American Canoe Association v. EPA; American Littoral Society, et al. v. EPA, et al.; DC DOH 1998; DC
DOE 2008; DE DNREC 1996; DE DNREC 2008; Kingman Park Civic Association, et al. vs. EPA; MDE 1998, 2004,
2008; USEPA 2008 a; VA DEQ 1998; VA DEQ 2008
a. BOD = biological oxygen demand; DO = dissolved oxygen; TN = total nitrogen; TP = total phosphorus; TSS = total
suspended solids
b. More than one river basin flows into this tidal segment
2-13
December 29,2010
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Chesapeake Bay TMDL
2.2.3 Jurisdictions' 2008 303(d) Listings
The Chesapeake Bay TMDL is based on the most recent EPA-approved tidal Bay jurisdictions'
section 303(d) lists, which are the 2008 303(d) listings." Those section 303(d) lists identity 89 of
the 92 Chesapeake Bay segments as impaired on either Category 4a (impaired, TMDL has been
developed) or Category 5 (impaired, needs TMDL) because of various factors, including low DO
levels, insufficient SAV, excess chlorophyll a, biological/nutrient indicators, total nitrogen, total
phosphorus, total suspended solids (TSS), biological oxygen demand (BOD), and pH (caused by
excessive nitrogen and phosphorus fueling algal blooms) (DC DOE 2008; DE DNREC 2008;
MDE 2008: VADEQ 2008).
Three Chesapeake Bay segments are not listed in Category 4a or 5 on Virginia's 2008 integrated
report:
• Upper Potomac Ri ver (POTTF V A)
• Middle Potomac River (POTOH_VA)
• Middle Rappahannock River (RPPOH)
Those three segments are listed as either Category 2 (some uses met, other uses have insufficient
information to determine impairment) or Category 3 (insufficient information to determine if
impaired) (VA DEQ 2008). Because their listing status raises a reasonable possibility that they
are impaired, and because those segments are tidally interconnected with other impaired Bay
segments, it is appropriate that they also be addressed by the Chesapeake Bay TMDL.
The first segment, Virginia's Upper Potomac River (POTTF VA), encompasses a series of small
tidal embayments that are tidally interconnected with Maryland's Upper Potomac River
(POTTF_MD) segment and the District of Columbia's Upper Potomac River (POTTF DC)
segment (USEPA 2008a), both of which are listed as Category 5 of Maryland's and the District
of Columbia's respective 2008 integrated reports (DCDOE 2008; MDE 2008). Loads originating
in the watershed that drains directly to Virginia's Upper Potomac River segment influence the
water quality in the two adjacent Maryland and District of Columbia impaired tidal segments and
other down-tide segments.
The second segment, Virginia's Middle Potomac River (POTOH VA), also encompasses a
series of small tidal embayments that are tidally interconnected with Maryland's Middle
Potomac River (POTOH_MD) segment (USEPA 2008a), which is listed as Category 5 on
Maryland's 2008 integrated report (MDE 2008). Loads originating in the watershed that drains
directly to Virginia's Middle Potomac River segment influence the water quality in the adjacent
Maryland impaired tidal segment and other down-tide impaired segments.
The third segment, Virginia's Middle Rappahannock River (RPPOH), is tidally interconnected
with both the Lower Rappahannock River (RPPMH) and the Upper Rappahannock River
(RPPTF) segments (USEPA 2008a), both of which are listed as Category 5 on Virginia's 2008
integrated report (VADEQ 2008). Loads originating in the watershed that drains directly to
2 At the time EPA applied the Bay models for development of the allocations starting in 2009, the 2008 section
303(d) lists were the most recent approved lists. Although EPA subsequently received 2010 section 303(d) lists for
approval from all tidal jurisdictions, EPA used the approved 2008 lists in establishing the Bay TMDL to have a
consistent basis for the TMDL.
2-14 December 29, 2010
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Chesapeake Bay TMDL
Virginia's Middle Rappahannock River segment influence the water quality in the adjacent
Virginia impaired tidal segments and other down-tide segments.
As detailed in Section 9, TMDLs have been completed as part of the Chesapeake Bay TMDL for
all 92 Chesapeake Bay segments listed in Table 2-1 (see Section 9). These include TMDLs for
the above described three Virginia Bay segments because they flow into impaired tidal Bay
segments, and reductions in nitrogen, phosphorus, and sediment loadings from their respective
watersheds, therefore, are necessary to achieve the Bay jurisdictions' Chesapeake Bay WQS.
2.2.4 2008 303(d) Listing Segments Compared to Consent Decree and
MOU Segments
To ensure that EPA established TMDLs for all necessary Bay segments—all 2008 listed
segments, all Virginia, Delaware, and the District of Columbia TMDL consent decree segments,
and all Maryland MOU segments—EPA compared the 2008 listed segments with those included
on those consent decrees and MOUs (Table 2-1). In total, 77 segments are addressed by the
Virginia and District of Columbia consent decrees and the Maryland MOU: 22 segments are on
the Virginia TMDL consent decree; 2 segments are on the Delaware TMDL consent decree;
2 segments are on the District of Columbia TMDL consent decree; and 51 segments are on the
Maryland TMDL MOU (Table 2-2). The evaluation found that all segments of the Virginia
consent decree, Delaware consent decree, the District of Columbia consent decree, and Maryland
MOU are included in the list of 92 Chesapeake Bay segments for which nitrogen, phosphorus,
and sediment TMDLs have been established under the Bay TMDL.
Table 2-2. Comparison of consent decree/MOU segments with total number of Bay
segments
Jurisdiction
Virginia
District of Columbia
Maryland
Delaware
Total
Consent decree or MOU segments
22
2
51
2a
77
Chesapeake Bay segments
35
2
53
2
92
Source: Adapted from Table 2-1.
a Two consent decrees affect one Bay segment in Delaware, but TMDLs have already been established for both
waterbodies.
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December 29, 2010
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Chesapeake Bay TMDL
SECTION 3. CHESAPEAKE BAY WATER QUALITY
STANDARDS
WQS consist of four basic elements: designated uses, water quality criteria, an antidegradation
policy (to maintain and protect existing uses and high-quality waters), and general policies
(addressing implementation issues such as low flows, variances, and mixing zones). Designated
uses are a jurisdiction's goals and expectations for each of the individual surface waters
(e.g., coldwater fisheries, public water supply, and primary contact recreation). EPA's WQS
regulation defines designated uses as the "uses specified in WQS for each waterbody or segment,
whether or not they are being attained" (40 CFR 131.3). Water quality criteria may be numeric or
narrative, and represent a quality of water that supports a particular use. When water quality
criteria are met, water quality is expected to protect its designated use. Numeric water quality
criteria are generally chemical-specific and reflect specific levels of pollutants that, if found in
the waterbody. do not impair its designated uses (e.g., physical or chemical characteristics like
temperature, minimum concentration of DO, and the maximum concentrations of toxic
pollutants).
Starting in 1986, EPA and its CBP partners embarked on a process to synthesize scientific
evidence on the water quality requirements of hundreds of aquatic species and biological
communities inhabiting Chesapeake Bay and its tidal tributaries and embayments. The 1987
Chesapeake Bay Agreement included a commitment to "develop and adopt guidelines for the
protection of water quality and habitat conditions necessary to support the living resources found
in the Chesapeake Bay system, and to use these guidelines in the implementation of water quality
and habitat quality programs" (CEC 1987). The CBP partnership initially published two
syntheses of the available scientific findings supporting establishment of habitat requirements for
31 target species (CBP 1987; Funderburk et al. 1991). Those efforts spawned development and
publication of synthesis documents focused on DO requirements (Jordan et al. 1992) and
underwater Bay grasses habitat requirements (Batiuk et al. 1992, 2000). On the basis of that
work, in part, EPA published as guidance the Chesapeake Bay water quality criteria (USEPA
2003a) and the Chesapeake Bay refined aquatic life designated uses and attainability (USEPA
2003d) documents.
Guided by those efforts, Delaware, the District of Columbia, Maryland, and Virginia adopted
jurisdiction-specific Chesapeake Bay WQS regulations in 2004-2005 consistent with the EPA
published guidance. EPA then reviewed and approved the four tidal Bay jurisdictions1 WQS
submissions pursuant to CWA section 303(c).
Since 2005, Delaware, Maryland, Virginia, and the District of Columbia each has proposed and
adopted very specific amendments to its respective Chesapeake Bay WQS regulations. Each
jurisdiction's process for amending its existing Chesapeake Bay WQS regulations requires full
public notice, public review and comment, and response to public comments before submission
to EPA Region 3 for final EPA review and approval.
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Chesapeake Bay TMDL
3.1 CHESAPEAKE BAY WATER QUALITY CRITERIA AND
DESIGNATED USES
The above described DO, underwater Bay grasses, and Bay habitat requirements documents
(Batiuketal. 1992, 2000; CBP 1987: Funderburk ct al. 1991; Jordan et al. 1991), supplemented
by additional scientific research findings, provided the basis for developing the applicable water
quality criteria guidance for the Chesapeake Bay. The criteria assessment guidance is
documented within EPA's Bay criteria (USEPA 2003a), designated uses/attainability (USEPA
2003d), and Bay segmentation (USEPA 2004b) documents and the subsequent seven addenda
(USEPA 2004a, 2004e, 2005, 2007a. 2007b, 2008a. 2010a). EPA Region 3 published those
documents as guidance in accordance with CWA sections 117(b) and 303 to derive water quality
criteria specifically for addressing the critical nutrient and sediment enrichment parameters
necessary to protect designated aquatic life uses in the Bay (Table 3-1). These criteria serve as
surrogate numeric criteria for nitrogen, phosphorus, and sediment.
Table 3-1. Chesapeake Bay water quality criteria and designated use related
documentation and addenda
Document title
Month/year
published
Document content and description
Ambient Water Quality Criteria for
Dissolved Oxygen, Water Clarity and
Chlorophyll a for the Chesapeake Bay
and Its Tidal Tributaries. EPA 903-R-03-
002. [USEPA 2003a]
April 2003
Original Chesapeake Bay water quality
criteria document.
Technical Support Document for
Identification of Chesapeake Bay
Designated Uses and Attainability. EPA
903-R-03-004. [USEPA 2003d]
October 2003
Original Chesapeake Bay tidal waters
designated uses document.
Ambient Water Quality Criteria for
Dissolved Oxygen, Water Clarity and
Chlorophyll a for the Chesapeake Bay
and Its Tidal Tributaries—2004
Addendum. EPA 903-R-03-002. [USEPA
2004a]
October 2004
Addresses endangered species
protection, assessment of DO criteria,
derivation of site-specific DO criteria,
pycnocline boundary delineation
methodology, and updated water clarity
criteria/SAV restoration acreage
assessment procedures.
Technical Support Document for
Identification of Chesapeake Bay
Designated Uses and Attainability—2004
Addendum. EPA 903-R-04-006. [USEPA
2004e]
October 2004
Addresses refinements to Bay tidal waters
designated use boundaries, segmentation
boundaries, and Potomac River
jurisdictional boundaries; documents SAV
no-grow zones, restoration goal, and
shallow-water acreages.
Chesapeake Bay Program Analytical
Segmentation Scheme: Revisions,
Decisions and Rationales 1983-2003.
EPA 903-R-04-008. CBP^TRS 268-04.
[USEPA 2004b]
October 2004
Details documentation on the history of
the segmentation schemes and provides
coordinates, georeferences, and narrative
descriptions of the 2003 segmentation
scheme.
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December 29, 2010
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Chesapeake Bay TMDL
Document title
Month/year
published
Document content and description
Chesapeake Bay Program Analytical
Segmentation Scheme: Revisions,
Decisions and Rationales 1983-2003:
2005 Addendum. EPA 903-R-05-004.
CBP/TRS 278-06. [USEPA 2005]
December
2005
Addresses methods used to subdivide the
segments by jurisdiction and provides
coordinates, georeferences, and narrative
descriptions for those subdivided
segments.
Ambient Water Quality Criteria for
Dissolved Oxygen, Water Clarity and
Chlorophyll a for the Chesapeake Bay
and Its Tidal Tributaries—2007
Addendum. EPA 903-R-07-003.
CBPmRS 285-07. [USEPA 2007a]
July 2007
Addresses refinements to the Bay water
quality DO, water clarity/SAV, and
chlorophyll a criteria assessment
methodologies and documents the
framework for Bay tidal waters 303(d) list
decision making.
Ambient Water Quality Criteria for
Dissolved Oxygen, Water Clarity and
Chlorophyll a for the Chesapeake Bay
and Its Tidal Tributaries—2007
Chlorophyll Criteria Addendum. EPA 903-
R-07-005. CBP/TRS 288/07. [USEPA
2007b]
November
2007
Publishes a set of numerical chlorophyll a
criteria for Chesapeake Bay and the
supporting criteria assessment
procedures.
Ambient Water Quality Criteria for
Dissolved Oxygen, Water Clarity and
Chlorophyll a for the Chesapeake Bay
and Its Tidal Tributaries—2008 Technical
Support for Criteria Assessment Protocols
Addendum. EPA 903-R-08-001.
CBP/TRS 290-08. [USEPA 2008a]
September
2008
Addresses refinements to the Bay water
quality DO, water clarity/SAV and
chlorophyll a criteria assessment
methodologies and documents the 2008
92-segment scheme for Bay tidal waters.
Ambient Water Quality Criteria for
Dissolved Oxygen, Water Clarity and
Chlorophyll a for the Chesapeake Bay
and Its Tidal Tributaries—2070 Technical
Support for Criteria Assessment Protocols
Addendum. EPA 903-R-10-002.
CBP/TRS 301-10. [USEPA 201 Oa]
May 2010
Addresses refinements to procedures for
defining designated uses, procedures for
deriving biologically based reference
curves for DO criteria assessment and
chlorophyll a criteria assessment
procedures.
Before adoption into each Bay jurisdiction's WQS regulations, each set of criteria, criteria
assessment procedures, designated uses, and proposed WQS were subject to extensive scientific,
programmatic, and public review.
The original 2003 water quality criteria, assessment procedures, and designated uses all went
through independent scientific peer reviews sponsored by the CBP's STAC and public review.
The CBP's Water Quality Steering Committee's water quality criteria and designated use teams
then reviewed and approved them. Finally, the CBP's Water Quality Steering Committee
reviewed and approved them for EPA publication on behalf of the partnership.
Since the publication of the original Chesapeake Bay water quality criteria document (USEPA
2003a), Chesapeake Bay designated uses and attainability document (USEPA 2003d), and
Chesapeake Bay segmentation document (USEPA 2004b), EPA has published enhancements to
the criteria assessment procedures, designated use boundaries, and Bay segmentation scheme.
Specifically, EPA has published five addenda—USEPA 2004a, 2007a, 2007b, 2008a, 2010a—to
the original 2003 Bay criteria document (USEPA 2003a), one addendum—USEPA 2004e—to
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Chesapeake Bay TMDL
the original 2003 Bay designated use/attainability document (USEPA 2003d), and one
addendum—USEPA 2005—to the original Bay segmentation document (USEPA 2004b) (see
Table 3-1).
Those revisions have undergone independent scientific peer reviews, sponsored by the CBP's
STAC, before review and approval by the CBP's Criteria Assessment Protocols Workgroup and
then the Water Quality Steering Committee/Water Quality Implementation Team for EPA
publication on behalf of the partnership. Examples include the cumulative frequency distribution
approach (STAC 2006) and the biological reference curves (STAC 2009).
3.1.1 Tidal Water Designated Uses
EPA and its seven watershed jurisdiction partners agreed on five refined aquatic life designated
uses reflecting the habitats of an array of recrcationally, commercially, and ecologically
important species and biological communities (USEPA 2003d, 2004e, 20lOa). The five tidal Bay
designated uses are applied, where appropriate, consistently across Delaware, the District of
Columbia, Maryland, and Virginia's portions of the Chesapeake Bay and its tidal tributary and
embayment waters. The vertical and horizontal breadth and temporal application of the
designated use boundaries are based on a combination of natural factors, historical records,
physical features, hydrology, bathymetry, and other scientific considerations (USEPA 2003d.
2004e, 20lOa). fable 3-2 outlines the Chesapeake Bay tidal water designated uses, which are
illustrated in Figure 3-1.
Table 3-2. Five Chesapeake Bay tidal waters designated uses
Tidal water designated use
Migratory fish spawning and
nursery
Shallow-water Bay grass
Open-water fish and shellfish
Deep-water seasonal fish and
shellfish
Deep-channel seasonal
refuge
Chesapeake Bay habitats and communities protected
Migratory and resident tidal freshwater finfish during the late
winter/spring spawning and nursery season in tidal freshwater to low-
salinity habitats.
Underwater Bay grasses and fish and crab species that depend on the
shallow-water habitat provided by underwater Bay grass beds.
Diverse populations of sport fish, including striped bass, bluefish,
mackerel and sea trout, as well as important bait fish such as
menhaden and silversides in surface water habitats within tidal creeks,
rivers, embayments, and the mainstem Chesapeake Bay year-round.
Animals inhabiting the deeper transitional water column and bottom
habitats between the well-mixed surface waters and the very deep
channels during the summer months (e.g., bottom-feeding fish, crabs
and oysters, as well as other important species, including the Bay
anchovy).
Bottom-sediment-dwelling worms and small clams that serve as food
for bottom-feeding fish and crabs in the very deep channels in summer.
Sources USEPA 2003d, 2004e
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December 29, 2010
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Chesapeake Bay TMDL
Refined Designated Uses for
the Bay and Tidal Tributary Waters
A. Cross Section of Chesapeake Bay or Tidal Tributary
Shallow-Water
Bay Grass Use
Open-Water
Fish and Shellfish Use
Deep-Water
Seasonal Fish and
Shellfish Use
Deep-Channel
Seasonal Refuge Use
B. Oblique View of the "Chesapeake Bay" and its Tidal Tributaries
Shallow-Water
Bay Grass Use
Deep-Water
Seasonal Fish and
Shellfish Use
Migratory Fish
Spawning and
Nursery Use
Deep-Channel Seasonal Refuge Use
Source: USEPA 2003d
Figure 3-1. Conceptual illustration of the five Chesapeake Bay tidal water designated use zones.
Table 3-3 lists the designated uses for each of the 92 Chesapeake Bay segments pursuant to
Delaware, the District of Columbia, Maryland, and Virginia's existing WQS regulations.
Amended based on USEPA 20lOa, Table 3-3 was originally published as Table V-l on pages
51-53 of the Ambient Water Quality Criteria for Dissolved Oxygen, Water Clarity and
Chlorophyll a for (he Chesapeake Bay and Its Tidal Tributaries 2007 Addendum (USEPA
2007a), which is an updated version of Table IV-3 originally published on pages 62-63 of the
2003 Technical Support Document for Identification of Chesapeake Bay Designated Uses and
Attainability (USEPA 2003d). The absence of an X in the shallow-water Bay grass designated
use column indicates that the Bay segment has been entirely delineated as an SAV no-grow zone
and, therefore, the shallow-water Bay grass designated use does not apply to that Bay segment
(USEPA 2004e).
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December 29, 2010
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Chesapeake Bay TMDL
Table 3-3. Current tidal water designated uses by Chesapeake Bay segment
CB segment name
Northern Chesapeake Bay
Upper Chesapeake Bay
Upper Central
Chesapeake Bay
Middle Central
Chesapeake Bay
Lower Central
Chesapeake Bay , MD
Lower Central
Chesapeake Bay, VA
Western Lower
Chesapeake Bay
Eastern Lower
Chesapeake Bay
Mouth of the Chesapeake
Bay'
Bush River
Gunpowder River
Middle River
Back River
Patapsco River
Magothy River
Severn River
South River
Rhode River
West River
Upper Patuxent River
Western Branch Patuxent
River
Middle Patuxent River
Lower Patuxent River
Upper Potomac River, DC
Upper Potomac River, MD
Upper Potomac River, VA
Anacostia River, DC
Anacostia River, MD
Piscataway Creek
Mattawoman Creek
CB segment
CB1TF
CB20H
CB3MH
CB4MH
CB5MH_MD
CB5MH_VA
CB6PH
CB7PH
CB8PH
BSHOH
GUNOH
MIDOH
BACOH
PATMH
MAGMH
SEVMH
SOUMH
RHDMH
WSTMH
PAXTF
WBRTF
PAXOH
PAXMH
POTTF_DC
POTTF_MD
POTTF_VA
ANATF_DC
ANATF_MD
PISTF
MATTF
Juris.
MD
MD
MD
MD
MD
VA
VA
VA
VA
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
DC
MD
VA
DC
MD
MD
MD
Migratory
fish
spawning
& nursery
Feb. 1-
May31
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Open
water fish
& shellfish
Year-round
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Deep
water
seasonal
fish&
shellfish
June 1-
Sept. 30
X
X
X
X
X
X
X
X
X
X
X
Deep
channel
seasonal
refuge
June 1-
Sept. 30
X
X
X
X
Shallow
water Bay
grasses
SAV
growing
season
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
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December 29, 2010
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Chesapeake Bay TMDL
CB segment name
Middle Potomac River,
MD-Mainstem
Middle Potomac River,
MD-Nanjemoy Creek
Middle Potomac River,
MD-Port Tobacco River
Middle Potomac River, VA
Lower Potomac River, MD
Lower Potomac River, VA
Upper Rappahannock
River
Middle Rappahannock
River
Lower Rappahannock
River
Corrotoman River
Piankatank River
Upper Mattaponi River
Lower Mattaponi River
Upper Pamunkey River
Lower Pamunkey River
Middle York River
Lower York River
Mobjack Bay
Upper James River-Lower
Upper James River-Upper
Appomattox River
Middle James River
Chickahominy River
Lower James River
Mouth of the James River
Western Branch Elizabeth
River
Southern Branch Elizabeth
River
Eastern Branch Elizabeth
River
Lafayette River
Mouth of the Elizabeth
^iver
CB segment
POTOH1_MD
POTOH2_MD
POTOH3_MD
POTOH_VA
POTMH MD
POTMH VA
RPPTF
RPPOH
RPPMH
CRRMH
PIAMH
MPNTF
MPNOH
PMKTF
PMKOH
YRKMH
YRKPH
MOBPH
JMSTF1
JMSTF2
APPTF
JMSOH
CHKOH
JMSMH
JMSPH
WBEMH
SBEMH
EBEMH
LAFMH
ELIPH
Juris.
MO
MD
MD
VA
MD
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA,
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
Migratory
fish
spawning
& nursery
Feb. 1-
May31
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Open
water fish
& shellfish
Year-round
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Deep
water
seasonal
fish&
shellfish
June 1-
Sept. 30
X
X
X
X
X
Deep
channel
seasonal
refuge
June 1-
Sept. 30
X
X
X
X
Shallow
water Bay
grasses
SAV
growing
season
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
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Chesapeake BayTMDL
CB segment name
Lynnhaven River
Northeast River
C&D Canal, DE
C&D Canal, MD
Bohemia River
Elk River
Sassafras River
Upper Chester River
Middle Chester River
Lower Chester River
Eastern Bay
Upper Choptank River
Middle Choptank River
Lower Choptank River
Mouth of the Choptank
River
Little Choptank River
Honga River
Fishing Bay
Upper Nanticoke River,
MD
Upper Nanticoke River, DE
Middle Nanticoke River
Lower Nanticoke River
Wicomico River
Manokin River
Big Annemessex River
Upper Pocomoke River
Middle Pocomoke River,
MD
Middle Pocomoke River,
VA
Lower Pocomoke River,
MD
Lower Pocomoke River,
VA
Tangier Sound, MD
CB segment
LYNPH
NORTF
C&DOH DE
C&DOH_MD
BOHOH
ELKOH
SASOH
CHSTF
CHSOH
CHSMH
EASMH
CHOTF
CHOOH
CHOMH2
CHOMH1
LCHMH
HNGMH
FSBMH
NANTF_MD
NANTF_DE
NANOH
NANMH
WICMH
MANMH
BIGMH
POCTF
POCOH_MD
POCOH_VA
POCMH_MD
POCMH_VA
TANMH_MD
TANMH_VA
Juris.
VA
MD
DE
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
DE
MD
MD
MD
MD
MD
MD
MD
VA
MD
VA
MD
VA
Migratory
fish
spawning
& nursery
Feb. 1-
May31
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Open
water fish
& shellfish
Year-round
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Deep
water
seasonal
fish&
shellfish
June 1-
Sept. 30
X
X
Deep
channel
seasonal
refuge
June 1-
Sept. 30
X
X
Shallow
water Bay
grasses
SAV
growing
season
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
x
Sources: USEPA 2003d, 2004e, 2007a, 201 Oa J
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Chesapeake Bay TMDL
3.1.2 Dissolved Oxygen Criteria
Oxygen is one of the most essential environmental constituents supporting life. In the
Chesapeake Bay's deeper waters, there is a natural tendency toward reduced DO conditions
because of the Bay's physical morphology and estuarine circulation. The Chesapeake Bay's
highly productive shallow waters, coupled with strong density stratification (preventing
reaeration); long residence times (weeks to months); low tidal energy; and tendency to retain,
recycle, and regenerate nutrients from the surrounding watershed all set the stage for low DO
conditions.
Against that backdrop, EPA worked closely with its seven watershed partners and the larger Bay
scientific community to derive and publish a set of DO criteria to protect specific aquatic life
communities and reflect the Chesapeake Bay's natural processes that define distinct habitats
(Figure 3-2) (USEPA 2003a; Batiuk et al. 2009). Working with the National Marine Fisheries
Service, EPA also ensured that the DO criteria were protective of the shortnose sturgeon, a
species listed as endangered by the Endangered Species Act (NMFS 2003; USEPA 2003b).
Minimum Amount of
Bay Disso ved Oxygen Criteria _.
Oxygen (mg/L) Needed to
Survive by Species
Migratory Fish Spawning
Fig 3-2 & Nursery Areas
Shallow and Open
Water Areas
Deep Water
Deep Channel
5
Striped Bass: 5-6'
i
American Shad: 5
White
Perch: 5
Hard Clams: 5
Yellow Perch: 5
Alewife: 3.6
5: 3 Bay Anchovy: 3
Spot: 2 Q.
Worms: 1
Source: USEPA 2003a
Figure 3-2. Dissolved oxygen concentrations (mg/L) required by different Chesapeake Bay species and
biological communities.
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Criteria for the migratory fish spawning and nursery, shallow-water Bay grass and open-water
fish and shellfish designated uses were set at levels to prevent impairment of growth and to
protect the reproduction and survival of all organisms living in the open-water column habitats
(Table 3-4) (USEPA 2003a). Criteria for deep-water seasonal fish and shellfish designated use
habitats, during seasons when the water column is significantly stratified, were set at levels to
protect juvenile and adult fish, shellfish, and the recruitment success of the Bay anchovy. Criteria
for deep-channel seasonal refuge designated use habitats in summer were set to protect the
survival of bottom sediment-dwelling worms and clams.
Table 3-4. Current Chesapeake Bay DO criteria
Designated
use
Migratory fish
spawning
and
nursery use
Shallow-water
Bay grass use
Open-water
fish and
shellfish use
Deep-water
seasonal fish
and shellfish
use
Deep-channel
seasonal
refuge use
Criteria
concentration/duration
7-day mean s 6 mg/L
(tidal habitats with 0-0.5 ppt
salinity}
Instantaneous minimum
Z 5 mg/L
Protection provided
Survival and growth of
larval/juvenile tidal-fresh resident
fish; protective of
threatened/endangered species
Survival and growth of
larval/juvenile migratory fish;
protective of
threatened/endangered species
Open-water fish and shellfish designated use criteria apply
Open-water fish and shellfish designated use criteria apply
30-day mean £ 5.5 mg/L
(tidal habitats with 0-0.5 ppt
salinity)
30-day mean £ 5 mg/L
(tidal habitats with >0.5 ppt
salinity)
7-day mean z 4 mg/L
Instantaneous minimum
s 3.2 mg/L
30-day mean £ 3 mg/L
1 -day mean > 2.3 mg/L
Instantaneous minimum
z 1.7 mg/L
Growth of tidal-fresh juvenile and
adult fish; protective of
threatened/endangered species
Growth of larval, juvenile, and
adult fish and shellfish; protective
of threatened/endangered species
Survival of open-water fish larvae
Survival of threatened/endangered
sturgeon species8
Survival and recruitment of Bay
anchovy eggs and larvae
Survival of open-water juvenile
and adult fish
Survival of Bay anchovy eggs and
larvae
Open-water fish and shellfish designated use criteria apply
Instantaneous minimum
z 1 mg/L
Survival of bottom-dwelling worms
and clams
Open-water fish and shellfish designated use criteria apply
Temporal
application
February 1-May 31
June 1-January 31
Year-round
Year-round
June 1-September
30
October 1-May 31
June 1 -September
30
October 1-May 31
Source: USEPA 2003a
Notes: mg/L = milligrams per liter; ppt = parts per thousand salinity
a. At temperatures considered stressful to shortnose sturgeon (> 29 degrees Celsius), DO concentrations above an
instantaneous minimum of 4.3 mg/L will protect survival of this listed sturgeon species.
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3.1.3 Chlorophyll a Criteria
EPA's 2003 Ambient Water Quality Criteria for Dissolved Oxygen, Water Clarity and
Chlorophyll a for the Chesapeake Bay and Its Tidal Tributaries (USKPA 2003a) describes the
applicable narrative criteria for chlorophyll a:
"Concentrations of chlorophyll a in free-floating microscopic aquatic plants (algae) shall not
exceed levels that result in ecologically undesirable consequences—such as reduced water
clarity, low dissolved oxygen, food supply imbalances, proliferation of species deemed
potentially harmful to aquatic life or humans or aesthetically objectionable conditions or
otherwise render tidal waters unsuitable for designated uses."
In 2007 EPA published numeric chlorophyll a criteria guidance protective of open-water
designated use impairment by harmful algal blooms and provided recommended reference
chlorophyll a concentrations for historic chlorophyll a levels, and DO and water clarity
impairments (USEPA 2007b).
Delaware, the District of Columbia, Maryland, and Virginia all adopted EPA's narrative
chlorophyll a criteria. Additionally, the District of Columbia and Virginia adopted numeric
chlorophyll a criteria for certain tidal waters as detailed in Sections 3.2.2 and 3.2.7. respectively.
3.1.4 Water Clarity/Underwater Bay Grasses Criteria
Underwater bay grass beds create rich animal habitats that support the growth of diverse fish and
invertebrate populations. Underwater bay grasses, also referred to as submerged aquatic
vegetation (SAV), help improve tidal water quality by retaining nitrogen and phosphorus as plant
material, stabilizing bottom sediment (preventing their resuspension) and reducing shoreline
erosion. The health and survival of such underwater plant communities in the Chesapeake Bay
and its tidal tributaries and embayments depend on suitable environmental conditions (Dennison
et al. 1993; Kemp et al. 2004).
The loss of SAV from the shallow waters of the Chesapeake Bay, which was first noted in the
early 1960s, is a widespread, well-documented problem (Orth and Moore 1983; Orth et al.
201 Ob). The primary causes of the decline of SAV are nutrient over-enrichment, increased
suspended sediment in the water, and associated reductions in light availability (Kemp et al.
2004). To restore the critical habitats and food sources, enough light must penetrate the shallow
waters to support the survival, growth, and repropagation of diverse, healthy, SAV communities
(Dennison et al. 1993).
EPA, working closely with its seven watershed partners and the larger Bay scientific community,
derived and published Chesapeake Bay water clarity criteria to establish the minimum level of
light penetration required to support the survival, growth, and continued propagation of SAV
(USEPA 2003a). Chesapeake Bay-specific water clarity criteria were derived for low and higher
salinity habitats using a worldwide literature synthesis, an evaluation of Chesapeake Bay-specific
field study findings, and application model simulations and diagnostic tools (Table 3-5).
The water clarity criteria, applied only during the SAV growing seasons, are presented in terms of
the percent ambient light at the water surface extending through the water column and the
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Chesapeake Bay TMDL
equivalent Secchi depth by application depth (Table 3-5). The recommended percent light-through-
water criteria can be directly measured using a Secchi disk or a light meter. A specific application
depth is required to apply and determine attainment of the water clarity criteria (Table 3-6).
SAV restoration acreage goals and water clarity application depths were developed based on
historic and recent data on the distribution of SAV (USEPA 2003d). Detailed analyses using that
data—including historical aerial photographs—were undertaken to map the distribution and
depth of historical SAV beds in the Chesapeake Bay and its tidal tributaries and embayments.
The analyses led to the adoption of the single best year method that considers historical SAV
distributions from the 1930s through the early 1970s and more recent distributions since 1978 to
the present mapped through annual SAV aerial surveys of the Bay's shallow-water habitats.
Using that method, the EPA and its watershed partners established a Bay-wide SAV restoration
goal of 185,000 acres and Bay segment-specific acreage goals (Table 3-6) (USEPA 2003d).
Table 3-5. Summary of Chesapeake Bay water clarity criteria for application to shallow-
water Bay grass designated use habitats
Salinity
regime"
Tidal-fresh
Oligohaline
Mesohaline
Polyhaline
Water clarity
criteria
(percent light-
through^-
water)
13%
13%
22%
22%
Water clarity criteria as Secchi depth3
Water clarity criteria application depths
(meters)
0.25
0.5
0.75
1.0
1.25
1.5
1.75
2.0
Secchi depth for above criteria application depth
(meters)
0.2
0.2
0.2
0.2
0.4
0.4
0.5
0.5
0.5
0.5
0.7
0.7
0.7
0.7
1.0
1.0
0.9
0.9
1.2
1.2
1.1
1.1
1.4
1.4
1.2
1.2
1.7
1.7
1.4
1.4
1.9
1.9
Temporal
application
April 1-Oct 31
April 1-Oct 31
April 1-Oct 31
March 1-May 31
Sept 1-Nov 30
Source: USEPA 2003a
a. Based on application of the Equation IV-1 published in USEPA 2003a, PLW= 10Oexp(-KdZ), where the appropriate
percent light through water (PLW) criterion value and the selected application depth (see Table 3-6) are inserted and
the equation is solved for Kd. The generated Ka value is then converted to Secchi depth (in meters) using the
conversion factor Kd= 1.45/Secchi depth.
b. Tidal fresh = 0-0.5 ppt salinity; oligohaline = >0.5-5 ppt salinity; mesohaline = >5-18 ppt salinity; polyhaline = >18
ppt salinity
Table 3-6. Chesapeake Bay SAV restoration acreage goals and application depths
Segment description
Northern Chesapeake Bay
Northern Chesapeake Bay
Upper Chesapeake Bay
Upper Central Chesapeake Bay
Middle Central Chesapeake Bay
Lower Central Chesapeake Bay
Lower Central Chesapeake Bay
Western Lower Chesapeake Bay
State
MD
MD
MD
MD
MD
MD
VA
VA
Segment
designator
CB1TF2
CB1TF1
CB20H
CB3MH
CB4MH
CB5MH MD
CB5MH VA
CB6PH
SAV acreage
restoration goal
(acres)
12,149
754
705
1,370
2,533
8,270
7,633
1,267
Application
depth
(meters)
2.0
1.0
0.5
0.5
2.0
2.0
2.0
1.0
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December 29, 2010
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Chesapeake Bay TMDL
Segment description
Eastern Lower Chesapeake Bay
Mouth of Chesapeake Bay
Bush River
Gunpowder River-Upper
Gunpowder River-Lower
Middle River
Back River
Patapsco River
Magothy
Severn River
South River
Rhode River
West River
Upper Patuxent River
Middle Patuxent River
Lower Patuxent River
Lower Patuxent River
Lower Patuxent River
Lower Patuxent River
Upper Potomac River
Piscataway Creek
Mattawoman Creek
Middle Potomac River
Middle Potomac River
Middle Potomac River
Lower Potomac River
Upper Potomac River
Middle Potomac River
Lower Potomac River
Upper Rappahannock River
Middle Rappahannock River
Lower Rappahannock River
Corrotoman River
Piankatank River
Upper Mattaponi River
Upper Pamunkey River
Middle York River
Lower York River
Mobjack Bay
Upper James River-Upper
Upper James River-Lower
Appomattox River
Middle James River
State
VA
VA
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
Segment
designator
CB7PH
CB8PH
BSHOH
GUNOH2
GUNOH1
MIDOH
BACOH
PATMH
MAGMH
SEVMH
SOUMH
RHDMH
WSTMH
PAXTF
PAXOH
PAXMH1
PAXMH2
PAXMH4
PAXMH5
POTTF MD
PISTF
MATTF
POTOH1
POTOH2
POTOH3
POTMH MD
POTTF VA
POTOH VA
POTMH VA
RPPTF
RPPOH
RPPMH
CRRMH
PIAMH
MPNTF
PMKTF
YRKMH
YRKPH
MOBPH
JMSTF2
JMSTF1
APPTF
JMSOH
SAV acreage
restoration goal
(acres)
15,107
11
350
572
1,860
879
30
389
579
455
479
60
238
205
115
1,459
172
1
2
2,142
789
792
1,387
262
1,153
7,088
2,093
1,503
4,250
66
4
1,700
768
3,479
85
187
239
2,793
15,901
200
1,000
379
15
Application
depth
(meters)
2.0
0.5
0.5
2.0
0.5
2.0
0.5
1.0
1.0
1.0
1.0
0.5
0.5
0.5
0.5
2.0
0.5
0.5
0.5
2.0
2.0
1.0
2.0
1.0
1.0
1.0
2.0
2.0
1.0
0.5
0.5
1.0
1.0
2.0
0.5
0.5
0.5
1.0
2.0
0.5
0.5
0.5
0.5
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Chesapeake Bay TMDL
Segment description
Chickahominy River
Lower James River
Mouth of the James River
Lynnhaven River
Northeast River
Chesapeake & Delaware Canal
Bohemia River
Elk River
Elk River
Sassafras River
Sassafras River
Upper Chester River
Middle Chester River
Lower Chester River
Eastern Bay
Middle Choptank River
Lower Choptank River
Mouth of Choptank River
Little Choptank River
Honga River
Fishing Bay
Middle Nanticoke River
Lower Nanticoke River
Wicomico River
Manokin River
Manokin River
Big Annemessex River
Big Annemessex River
Lower Pocomoke River
Lower Pocomoke River
Tangier Sound
Tangier Sound
Tangier Sound
State
VA
VA
VA
VA
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
VA
MD
MD
VA
Segment
designator
CHKOH
JMSMH
JMSPH
LYNPH
NORTF
C&DOH MD
BOHOH
ELKOH1
ELKOH2
SASOH1
SASOH2
CHSTF
CHSOH
CHSMH
EASMH
CHOOH
CHOMH2
CHOMH1
LCHMH
HNGMH
FSBMH
NANOH
NANMH
WICMH
MANMH1
MANMH2
BIGMH1
BIGMH2
POCMH MD
POCMH VA
TANMH1 MD
TANMH2 MD
TAHMH VA
SAV acreage
restoration goal
(acres)
535
200
300
107
89
7
354
1,844
190
1,073
95
1
77
2,928
6,209
72
1,621
8,184
4,076
7,761
197
12
3
3
4,294
59
2,021
22
877
4,066
24,683
74
13,579
AppJication
depth
(meters)
0.5
0.5
1.0
0.5
0.5
0.5
0.5
2.0
0.5
2.0
0.5
0.5
0.5
1.0
2.0
0.5
1.0
2.0
2.0
2.0
L 0.5
0.5
0.5
0.5
2.0
0.5
2.0
0.5
1.0
1.0
2.0
0.5
2.0
Sources: USEPA 2003d, 2004e; Code of Maryland Title 26 Subtitle 08, Chapter 2, Section 3; Code of Virginia 9 62.1-
44.15 3a; VAC 25-260-185; 7 Delaware Code section 6010; 7 Delaware Administrative Code 7401; District of
Columbia Municipal Regulations Title 21, Chapter 11.
Notes: This table contains additional split segments beyond the 92 Chesapeake Bay segments listed in Table 3-3
strictly for purposes of applying separate water clarity criteria application depths within the same Bay segment
(USEPA 2004e). If a Bay segment was listed in Table 3-3, but it is not listed here, that entire Bay segment has been
delineated as a SAV no-grow zone and the shallow-water bay grass does not apply (USEPA 2004e).
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3.2 JURISDICTIONS' CURRENT CHESAPEAKE BAY WATER
QUALITY STANDARDS REGULATIONS
Delaware, the District of Columbia, Maryland, and Virginia each has adopted WQS consistent
with EPA's published Chesapeake Bay water quality criteria, assessment procedures, and tidal
water designated uses in its respective WQS regulations (Table 3-7). In some cases, a jurisdiction
also adopted jurisdiction-specific designated uses or criteria or both; those cases are briefly
described below.
Table 3-7. Links for accessing the current waters quality standards (WQS) regulations for
Delaware, the District of Columbia, Maryland, and Virginia
Jurisdiction
Delaware
District of
Columbia
Maryland
Virginia
WQS regulations URL address
7 Delaware Code Section 6010; 7 Delaware Administrative Code 7401
DC Municipal Regulations Title 21, Chapter 11
Code of Maryland Title 26 Subtitle 08, Chapter 2
Code of Virginia 9 62.1-44.1 5 3a; VAC 25-260 Virginia WQSs
OR
3.2.1 Delaware
Delaware has adopted all the EPA-published Chesapeake Bay criteria, assessment procedures,
designated use documents, and subsequent addenda listed in Table 3-1 by reference into its WQS
regulations. The EPA-published Chesapeake Bay criteria, assessment procedures, and designated
use documents and subsequent addenda apply to the tidal Nanticoke River and Broad Creek in
Delaware, both of which are subject to this Chesapeake Bay TMDL (see Table 2-1). Delaware
has also adopted EPA's narrative chlorophyll a water quality criteria.
3.2.2 District of Columbia
The District of Columbia has adopted all the EPA-published Chesapeake Bay criteria,
assessment procedures, designated use documents, and subsequent addenda listed in Table 3-1
by reference into its WQS regulations. Table 3-8 summarizes the District of Columbia's
designated uses for its surface waters. The District of Columbia has adopted EPA's narrative
chlorophyll a water quality criteria but also adopted the numeric chlorophyll a water quality
criteria shown in Table 3-9 with respect to the District of Columbia's tidal Class C waters (those
designated for the protection and propagation offish, shellfish, and wildlife). Those numeric
chlorophyll a criteria are subject to this Chesapeake Bay TMDL (see Table 2-1).
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Chesapeake BayTMDL
Table 3-8. District of Columbia designated uses for surface waters
Class of water
A
B
C
D
E
Description
Primary contact recreation
Secondary contact recreation and aesthetic enjoyment
Protection and propagation offish, shellfish, and wildlife
Protection of human health related to consumption of fish and shellfish
Navigation
Source: District of Columbia Municipal Regulations Title 21, Chapter 11
Table 3-9. Numeric criteria for the District of Columbia's tidally influenced waters
Constituent
Dissolved
oxygen
Secchi depth
Chlorophyll a
Numeric criteria
7-day mean > 6.0 mg/L
Instantaneous minimum > 5.0 mg/L
30-day mean > 5.5 mg/L
7-day mean z 4.0 mg/L
Instantaneous minimum z 3.2 mg/L
(At temperatures > 29 °C, in tidally influenced
waters, an instantaneous minimum DO
concentration of 4.3 mg/L will apply)
0.8 m (seasonal segment average)
25 ug/L (season segment average)
Temporal application
February 1-May 31
June 1 -January 31
April 1 -October 31
July 1 -September 30
Designated
use
C
C
C
Source: District of Columbia Municipal Regulations Title 21, Chapter 11
Note: ug/L = micrograms per liter
3.2.3 Maryland
Maryland has adopted into its WQS regulations all the EPA-published Chesapeake Bay criteria.
assessment procedures, and designated uses documents, and subsequent addenda listed in Table
3-1. These WQS apply to all Chesapeake Bay, tidal tributary and embayment waters of
Maryland, all of which are subject to this Chesapeake Bay TMDL (see Table 2-1). Maryland has
also adopted EPA's narrative chlorophyll a water quality criteria.
Several tidal Bay segment-specific applications of DO criteria are unique to Maryland. In the
middle-central Chesapeake Bay segment (CB4MH), restoration variances' of 7 and 2 percent
apply to the application of the deep-water and deep-channel designated use DO criteria,
respectively. In the Patapsco River segment (PATMH), a restoration variance of 7 percent
applies to the application of the deep-water designated use DO criteria. In the lower Chester
River segment (CSHMH), a restoration variance of 14 percent applies to the application of the
deep-channel designated use DO criterion (COMAR 26.08.02.03-3(c)(8)(e)(vi). These
restoration variances are consistent with EPA-published guidance (USEPA 2003d) and were
1 A restoration variance is the percentage of allowable exceedance of a WQS based on water quality modeling
incorporating the best available data and assumptions. The restoration variances are temporary and will be reviewed
at a minimum every 3 years, as required by the CWA and EPA regulations. The variances could be modified on the
basis of new data or assumptions incorporated into the water quality model. COMAR 26.08.02.03-3(C)(8)(h).
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Chesapeake Bay TMDL
approved by EPA on August 29, 2005 in the case of the two mainstem Bay and Patapseo River
segments and December 27, 2010 in the case of the lower Chester River segment.
In the tidal upper and middle Pocomoke River segments (POCTF, POCOH MD), because of the
seasonal lower DO concentration from the natural oxygen-depleting processes present in the
extensive surrounding tidal wetlands, Maryland adopted a site-specific criterion of greater than
or equal to 4 mg/L 30-day mean DO, consistent with the EPA-published criterion (USEPA
2004a), and approved by EPA on December 27, 2010.
3.2.4 Virginia
Virginia has adopted into its WQS regulations all the EPA-published Bay criteria, assessment
procedures, designated uses documents, and subsequent addenda listed in Table 3-1. These WQS
apply to all Chesapeake Bay, tidal tributary and embayment waters of Virginia, all of which are
subject to this Chesapeake Bay TMDL. The narrative chlorophyll a criteria guidance published
by EPA (USEPA 2003a) was adopted by Virginia for application to Virginia's Bay tidal waters.
Virginia also adopted the segment-specific numeric chlorophyll a criteria for the tidal James
River listed in Table 3-10 into its WQS regulations. The criteria are based on various scientific
lines of evidence published in the original EPA 2003 Bay criteria document (USEPA 2003a)
with additional river-specific considerations (VADEQ 2004). EPA approved Virginia's WQS
regulations on June 27, 2005 and approved additional amendments on December 28, 2010.
Table 3-10. Segment-specific chlorophyll a criteria for Virginia's tidal James River waters
Designated
use
Open-Water
Chlorophyll a
criterion
(M9/M
10
15
15
12
12
15
23
22
10
10
Chesapeake Bay segment
Upper James River-Upper (JMSTF2)
Upper James River-Lower (JMSTF1)
Middle James River (JMSOH)
Lower James River (JMSMH)
Mouth of the James River (JMSPH)
Upper James River-Upper (JMSTF2)
Upper James River-Lower (JMSTF1)
Middle James River (JMSOH)
Lower James River (JMSMH)
Mouth of the James River (JMSPH)
Temporal application
March 1-May 31
July 1 -September 30
Source: Code of Virginia 9 section 62.1-44.15 3a; VAC 25-260
Note: pg/L = micrograms per liter
Virginia has additional site-specific DO and chlorophyll a criteria. In the tidal Mattaponi
(MPNTF, MPNOH) and Pamunkey (PMKTF, PMKOH) river segments, because of the seasonal
lower DO concentration from the natural oxygen-depleting processes present in the surrounding
extensive tidal wetlands, Virginia adopted a site-specific criterion of greater than or equal to 4
mg/L 30-day mean DO (9 VAC 25-260-185), consistent with the EPA-published criterion
(USEPA 2004a) and approved by EPA on June 27, 2005.
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3.3 ASSESSING ATTAINMENT OF CHESAPEAKE BAY WATER
QUALITY STANDARDS
The Bay criteria assessment approach is designed to protect the living resources as defined by
the designated uses (USEPA 2003a). The criteria levels themselves were largely based on
scientific studies performed in laboratory settings or under controlled field conditions. The
criteria establish the level of a given habitat condition that living resources need for survival.
They do not account for many other environmental factors that could affect survival.
For all four tidal jurisdictions, attainment of each jurisdiction's Chesapeake Bay WQS is
determined by applying the same set of assessment procedures published in the original 2003
Chesapeake Bay criteria document (USEPA 2003a) and subsequent published addenda (USEPA
2004a, 2007a, 2007b, 2008a, 2010a) (see Table 3-1). Those consistent sets of criteria assessment
procedures were formally adopted into each jurisdiction's WQS regulations by reference.
3.3.1 Defining Total Exceedances
Criteria attainment for DO, water clarity, and chlorophyll a is assessed in terms of the spatial and
temporal extent of criterion exceedances—what volume or surface area of the Bay segment
exceeds a given criterion and for how much time during the assessment period (USEPA 2003a,
2004a). The allowable frequency with which criteria can be violated without a loss of the
designated use is also considered. For each listing cycle, assessments are based on monitoring
data collected over a 3-year period in each spatial assessment unit. Spatial assessment units are
defined by Chesapeake Bay segments and applicable designated uses. Such assessment of the
criteria as further described below is designed to provide reliable protection for the associated
refined aquatic life use.
The spatial exceedances of criteria are determined using a grid cell-based data interpolation
software application that enables estimation of water quality values for the entire Bay using
monitored data at specific points (USEPA 2003a, 2007a). The interpolated data are compared to
water quality criteria on a cell by cell basis, and the percent of surface area or volume exceeding
the criterion in each spatial assessment unit is calculated. The percent spatial exceedances for
each assessment unit are then compiled for each monitoring event conducted during the 3-year
monitoring period.
The temporal extent of exceedances is determined by calculating the probability that an observed
percent exceedance will be equaled or exceeded. To calculate that probability, the percent of
spatial exceedances are sorted and ranked, and a cumulative probability is calculated for each
spatial exceedance value (USEPA 2003a). An example is shown in Table 3-11.
The spatial and temporal exceedances can be graphically illustrated by plotting the cumulative
frequency distribution (CFD) curve, which is a plot of the temporal exceedance values on the
Y-axis versus the spatial exceedance values (in area or volume) on the X-axis (Figure 3-3)
(USEPA 2003a, 2007a; STAC 2006).
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Chesapeake Bay TMDL
Table 3-11. Estimated percent spatial criteria exceedances and associated cumulative
probabilities
Period of data
June 1998
March 1998
May 1999
May 1998
April 1998
June 2000
March 1999
April 2000
May 2000
Apr 1999
June 1999
March 2000
Percent area/volume
exceeding criteria
(spatial)
100
75
72
67
65
55
50
49
39
35
34
25
20
Rank
1
2
3
4
5
6
7
8
9
10
11
12
Cumulative probability [rank / (n + 1)]
(temporal)
0.00%
7.69%
15.38%
23.08%
30.77%
38.46%
46.15%
53.85%
61.54%
69.23%
76.92%
84.62%
92.31%
Source: USEPA 2003a
Cumulative Frequency Distribution Curve
100.00%
90.00%
8000%
70.00%
60.00%
50.00%
40.00%
30.00%
20.00%
10.00%
0.00%
39% of more of the wet/volume
exceed** criteria in 62% of the
sampling events during the three-
year asieftsment period
10
20 30 40 50 60 70
% Area or Volume Exceeding Criteria
00 100
Source: USEPA 2003a
Figure 3-3. Example cumulative frequency distribution (CFD) curve.
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Chesapeake Bay TMDL
3.3.2 Defining Allowable Exceedances
EPA developed reference curves for each water quality criterion (DO, water clarity, and
chlorophyll a) to provide a scientifically based, direct measure of the time and space during
which a particular criterion can be allowably exceeded - i.e., without resulting in harm to the
designated uses(s) (USEPA 2003a). Those allowable exceedances are defined to be those that
last a short enough time or cover a small enough volume/surface area to have no adverse effects
on the designated use. It is assumed that the designated uses can be attained even with some
limited level of criteria exceedances and, thus, the reference curves define those criteria
exceedances deemed to be allowable—chronic in time but over small volumes/surface areas, or
infrequent occurrences over large volumes/surface areas. Exceedances that occur over large areas
of space and time would be expected to have significant detrimental effects on biological
communities, which would imply nonattainment of designated uses.
For assessment purposes, EPA developed two types of reference curves: a biological reference
curve and a 10 percent default reference curve for use when a biological reference curve is
unavailable.
Biological reference curves are CFDs developed for a given criterion in areas for which
monitoring data are available and in which healthy aquatic communities exist (USEPA 2003a).
They represent the range of conditions that can reasonably be expected in a healthy community.
As a result, the biological reference curve can be used to provide an understanding of what level
of criteria exceedances are allowable without losing support of the designated use. Given the
Bay's nutrient-enriched status, however, appropriate reference sites are limited. Biological
reference curves have been published for and are used to assess allowable exceedances for the
deep-water DO criteria (USEPA 2010a) and the water clarity criteria (USEPA 2003a).
In some cases, developing a biologically based reference curve is not possible because of a lack
of data describing the health of the relevant species or biological communities and lack of
appropriate reference sites. In those cases, EPA used a 10 percent default reference curve
(USEPA 2007a). The 10 percent default reference curve is defined as a hyperbolic curve that
encompasses no more than 10 percent of the area of the CFD graph (percent of space multiplied
by percent of time) (USEPA 2007a, page 13, Figure 11-4 and Equation 1) (Figure 3-4).
Once the CFD curve for a spatial assessment unit is developed from monitoring data (also
referred to as the assessment curve), it is compared to the appropriate reference curve. The area
on the graph above the reference curve (blue line) and below the assessment curve (red line) is
considered a non-allowable exceedance. The area below the reference curve (yellow) is
considered an allowable exceedance (Figure 3-5).
3-20 December 29, 2010
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Chesapeake Bay TMDL
Default 10% Curve
0.2
0.3
0.4
B.5
0.6
07
o.a
0.9
Source: USEPA 2007a
Figure 3-4. Default reference curve used in the attainment assessment of Chesapeake Bay water quality
criteria for which biologically based reference curves have not yet been derived.
100
90
80
| 70
£ 60
50
40
30
20
10
0
fc
Q_
Reference CFD Curve
Assessment CFD Curve
Area of Criteria
Exceedence
Area of Allowable
Criteria
Exceedence
0 10 20 30 40 50 60 70 80 90 100
Percent of Space
Source: USEPA 2003a
Figure 3-5. Example reference and assessment curves showing allowable and non-allowable exceedances.
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December 29, 2010
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Chesapeake Bay TMDL
3.3.3 Assessing Criteria A ttainmen t
Dissolved Oxygen Criteria Assessment
EPA published DO criteria protective of migratory fish spawning and nursery, open-water fish
and shellfish, deep-water seasonal fish and shellfish, and deep-channel seasonal refuge
designated use habitats. DO criteria were established for the Chesapeake Bay that varied in space
and time to provide levels of protection for different key species and communities (Table 3-4).
The criteria also were designed around several lengths of time to reflect the varying oxygen
tolerances for different life stages (e.g., larval, juvenile, adult) and effects (e.g., mortality,
growth, behavior) (USEPA 2003a).
The DO criteria include multiple components, including the target DO concentration, the
duration of time over which the concentration is averaged, the designated use area where the
criterion applies, the protection provided, and the time of year when the criterion applies
(USEPA 2003a. 2003d). The four tidal Bay jurisdictions adopted these DO criteria into their
respective WQS regulations.
Assessing DO criteria attainment is challenging because of the complexity of both the criteria
and the Bay itself. To fully assess all the criteria components, data needed to be collected at a
spatial intensity that adequately represents the four designated use habitats of Chesapeake Bay
tidal waters at different times of the year (USEPA 2003c, 2004e). Similarly, data were collected
during all the applicable seasons and at frequencies sufficient to address the various criteria
duration components.
The different DO criteria apply to different designated use areas and multiple criteria apply to the
same designated use area. The DO criteria components also apply over different periods to
protect species during critical life stages or during particularly stressful times of the year. To
fully assess each DO component in each designated use habitat over the appropriate periods will
require an extensive monitoring program and a detailed assessment methodology. The CBP
conducts extensive water quality and living resource monitoring throughout the Bay tidal waters
(CBP 1989a. 1989b; MRAT 2009). The existing Bay water quality monitoring was not sufficient
to cover all the criteria components, however, and some details in the assessment methodology
remain unresolved (USEPA 2007a; MRAT 2009).
The DO criteria include 30-day, 7-day, and 1-day means along with an instantaneous minimum.
The CBP partners have the capacity (data, published assessment methodology) to assess only the
30-day mean open-water and deep-water DO criteria and, in the case of the deep-channel use, the
instantaneous minimum DO criteria (USEPA 2003a, 2004a, 2007a, 2008a, 2010a). The
remaining DO criteria were not assessed because the existing water quality monitoring programs
and the published assessment methodologies are not yet adequate for full assessment.
Evaluation of the Chesapeake Bay Water Quality and Sediment Transport Model's outputs have
provided clear evidence that the 30-day mean open-water and deep-water and the instantaneous
minimum deep-channel DO criteria are the criteria driving determination of nutrient loadings
supporting attainment all the open-water (30-day mean, 7-day mean, instantaneous minimum),
deep-water (30-day mean, I-day and instantaneous minimum), and deep-channel (instantaneous
minimum) DO criteria.
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Chesapeake Bay TMDL
For both open-water and deep-water designated uses, the 30-day mean criteria had the highest
nonattainment in all three scenarios illustrated in Figure 3-6. The 30-day mean open-water and
deep-water criteria are, therefore, protective of the other non-assessed DO criteria (open-water
7-day and instantaneous minimum, deep-water I-day mean and instantaneous minimum) on
average for the mainstem Bay segments. The deep-channel designated use has only one DO
criterion, and it is currently assessed using monitoring data. The deep-channel criterion is also
more protective, based on the levels of nonattainment recorded in Figure 3-6, than the deep-
water and open-water criteria. The analyses documented in Appendix D provide clear evidence
the 30-day mean open-water, 30-day mean deep-water DO criteria, and the deep-channel
instantaneous minimum criterion are the most protective criteria across all Bay segments and
designated uses.
Chlorophyll a Criteria Assessment
The procedures described in USEPA 2007b, and further refined in USEPA 2010a. apply to
assessing Virginia's tidal James River and the District of Columbia's tidal waters numeric
chlorophyll u criteria.
To assess attainment of the Virginia and the District of Columbia's adopted numerical
chlorophyll a concentration-based criteria, it was necessary to establish a reference curve for use
in the CFD criteria assessment (USEPA 2003a, 2007a). In the case of the numerical chlorophyll
a criteria where a biologically based reference curve is not available (USEPA 2007b), EPA
recommends—and Virginia and the District of Columbia adopted—using the 10 percent default
reference curve originally described in USEPA 2007a and illustrated in Figure 3-4.
The jurisdiction-adopted, concentration-based chlorophyll a criteria values are threshold
concentrations that should be exceeded infrequently (< 10 percent) because a low number of
naturally occurring exceedances occur even in a healthy phytoplankton population (USEPA
2007b). The assessment of chlorophyll a criteria attainment, therefore, uses the CFD-based
assessment method described earlier that applies the 10 percent default reference curve. Such
concentration-based Chesapeake Bay chlorophyll a criteria apply only to those seasons and
salinity-based habitats for which they were defined to protect against applicable human health
and aquatic life impairments (USEPA 2007b). Each season—Spring (March 1-May 31) and
Summer (July 1-September 30)—was assessed separately to evaluate chlorophyll a criteria
attainment.
The chlorophyll a criteria are based on seasonal means of observed chlorophyll data. The
observed data are first transformed by taking the natural logarithm and then interpolated spatially
to equally spaced points (representing interpolator cells) within the designated use area for each
monitoring cruise. The interpolated value of each cell is averaged in time across the entire
season, and then the spatial violation rate is calculated as the fraction of interpolator cells in a
designated use area that fails the appropriate criterion (USEPA 2010a).
3-23 December 29, 2010
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Chesapeake BayTMDL
Direct model assessment of nonattainment—mainstem average
open water
DO Open Water Summer
Instantaneous
DO Open Water Weekly
DO Open Water Summer
Monthly
Calibrated Model
Moderate
Reduction
Large Reduction
Direct model assessment of nonattainment—mainstem average
deep water and deep channel
're
25%
20%
15%
10%
5%
IV
I
\
< 0%
i DO Deep Water Instantan
i DO Deep Water Daily
DO Deep Water Monthly
I DO Deep Channel
Instantaneous
Calibrated Moderate Large Reduction
Model Reduction
Source: Appendix D
Figure 3-6. Direct model assessment of open water (a), and deep water and deep channel (b) criteria.
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December 29, 2010
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Chesapeake Bay TMDL
SAV/Water Clarity Criteria Assessment
Water clarity criteria and SAV restoration acreages are used to define attainment of the shallow-
water Bay grass designated use in the Chesapeake Bay, its tidal tributaries and embayments
(USEPA 2003a, 2003d). EPA published three measures for assessing attainment of the shallow-
water SAV designated use for a Chesapeake Bay segment (USEPA 2007a):
1. Measure SAV acreage in the Bay segment from overflight data mapping
analysis and compare with the SAV restoration goal acreage for that Bay
segment (USEPA 2003d).
2. Measure water clarity acreage on the basis of routine water quality mapping
using data from the Chesapeake Bay shallow-water monitoring program and,
combined with measured acres of SAV, compare with the calculated water
clarity acres for that segment (USEPA 2007a).
3. Measure water clarity criteria attainment on the basis of the CFD assessment
methodology, again, using shallow-water monitoring program data (USEPA
2003a, 2003d, 2007a, 2008a).
Without sufficient shallow-water monitoring data to determine the available water clarity acres
(measurement 2 above) or to assess water clarity criteria attainment using the CFD-based
procedure (measurement 3 above), EPA recommends that the jurisdictions assess shallow-water
Bay grass designated use attainment using the acres of mapped SAV (measurement I above)
(USEPA 2003a, 2003d, 2007a, 2008a).
3-25 December 29, 2010
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Chesapeake Bay TMDL
SECTION 4. SOURCES OF NITROGEN, PHOSPHORUS
AND SEDIMENT TO THE CHESAPEAKE
BAY
Nitrogen, phosphorus, and sediment loads originate from many sources in the Bay watershed.
Point sources of nitrogen, phosphorus, and sediment include municipal wastewater facilities,
industrial discharge facilities, CSOs, SSOs, NPDES permitted stormwater (MS4s and
construction and industrial sites), and CAFOs. Nonpoint sources include agricultural lands
(AFOs, cropland, hay land, and pasture), atmospheric deposition, forest lands, on-site treatment
systems, nonregulated stormwater runoff, streambanks and tidal shorelines, tidal resuspension,
the ocean, wildlife, and natural background. Unless otherwise specified, the loading estimates
presented in this section are based on results of the Phase 5.3 Chesapeake Bay Watershed Model
(Bay Watershed Model). For a description of the Bay Watershed Model, see Section 5.8.
Estimates of existing loading conditions are based on the 2009 scenario run through the Bay
Watershed Model.
4.1 JURISDICTION LOADING CONTRIBUTIONS
Analysis of 2009 monitoring data and estimated modeling results shows that Pennsylvania
provided the largest proportion of nitrogen loads delivered to the Bay (44 percent), followed by
Virginia (27 percent), Maryland (20 percent), New York (4 percent), Delaware (2 percent) and
West Virginia (2 percent), and the District of Columbia (1 percent) (Figure 4-1). Delivered loads
are the amount of a pollutant delivered to the tidal waters of the Chesapeake Bay or its tributaries
from an upstream point. Delivered loads differ from edge-of-stream loads becauese of in-stream
processes in free-flowing rivers that naturally remove nitrogen and phosphorus from the system.
Total Nitrogen
WV DE DC
2%
Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario
Figure 4-1. Modeled estimated total nitrogen loads delivered to the Chesapeake Bay by jurisdiction in 2009.
4-1
December 29, 2010
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Chesapeake Bay TMDL
The model estimated phosphorus loads delivered to the Bay were dominated by Virginia (43
percent), followed by Pennsylvania (24 percent), Maryland (20 percent), New York (5 percent),
West Virginia (5 percent), Delaware (2 percent), and the District of Columbia (I percent) (Figure
4-2).
Total Phosphorus
Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario
Figure 4-2. Model estimated total phosphorus loads delivered to the Chesapeake Bay by jurisdiction in 2009.
Similar to the phosphorus loads, 2009 model estimated sediment loads delivered to the Bay are
dominated by Virginia (41 percent), followed by Pennsylvania (32 percent), Maryland (17
percent), West Virginia (5 percent), New York (4 percent), Delaware (1 percent), and the District
of Columbia (< 1 percent) (Figure 4-3).
Total Sediment
Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario
Figure 4-3. Model estimated total sediment loads delivered to the Chesapeake Bay by jurisdiction in 2009.
4-2
December 29, 2010
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Chesapeake Bay TMDL
4.2 MAJOR RIVER BASIN CONTRIBUTIONS
The major river basins' model-estimated contributions of total nitrogen loads delivered to the
Bay in 2009 are illustrated in Figure 4-4. The Susquehanna River basin, draining parts of New
York, Pennsylvania, and Maryland, is estimated to be responsible for almost half of the nitrogen
loads delivered to the Bay (46 percent). The next major contributor, at 22 percent, is the Potomac
River Basin, draining the entire District of Columbia and parts of Maryland, Pennsylvania.
Virginia, and West Virginia. The James River Basin (draining parts of Virginia and West
Virginia) contributes 12 percent of the nitrogen loads to the Bay; the Eastern Shore Basin
(draining parts of Delaware, Maryland, and Virginia) contibutes 8 percent of the nitrogen loads
to the Bay; and the Western Shore Basin (draining parts of Maryland) is estimated to be
responsible for 6 percent of the nitrogen loading to the Bay. Smaller portions, 3 percent, 2
percent, and 1 percent are contributed by the Rappahannock (Virginia), the York (Virginia) and
the Patuxent (Maryland) river basins, respectively (Figure 4-4).
Total Nitrogen
• Eastern Shore of
Chesapeake Bay
• James River Basin
• Patuxent River Basin
• Potomac River Basin
• Rappahannock River
Basin
• Susquehanna River Basin
i Western Shore of
Chesapeake Bay
> York River Basin
Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario
Figure 4-4. Model estimated total nitrogen loads delivered to the Chesapeake Bay by major tributary In 2009.
The major river basins' model estimated contributions to total phosphorus loads to the Bay in
2009 are illustrated in Figure 4-5. Three river basins—the Potomac (27 percent), the
Susquehanna (26 percent), and the James (20 percent)—are estimated to account for about three-
quarters of the total phosphorus loading to the Bay. The Eastern Shore contributes 10 percent of
the total phosphorus load, while the balance is provided by the Rappahannock (6 percent), the
Western Shore (5 percent), the York (4 percent), and the Patuxent (2 percent) river basins
(Figure 4-5).
The major river basins' model estimated contributions to total sediment loads to the Bay in 2009
are illustrated in Figure 4-6. The Susquehanna (33 percent) and Potomac (32 percent) river
basins are estimated to contribute the majority of the total sediment loads delivered to the
Chesapeake Bay, followed by the James (16 percent) and the Rappahannock (9 percent) river
4-3
December 29, 2010
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Chesapeake Bay TMDL
basins. The Eastern Shore (4 percent), Western Shore (3 percent), York (2 percent) and Patuxent
(1 percent) river basins each contribute relatively small total sediment loads (Figure 4-6).
Total Phosphorus
• Eastern Shore of
Chesapeake Bay
• James River Basin
•Patuxent River Basin
• Potomac River Basin
• Rappahannock River
Basin
2% • Susquehanna River Basin
• Western Shore of
Chesapeake Bay
• York River Basin
Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario
Figure 4-5. Model estimated total phosphorus loads delivered to the Chesapeake Bay by major tributary in
2009.
Total Sediment
• Eastern Shore of
Chesapeake Bay
• James River Basin
•Patuxent River Basin
• Potomac River Basin
• Rappahannock River
Basin
• Susquehanna River Basin
• Western Shore of
Chesapeake Bay
• York River Basin
Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario
Figure 4-6. Model estimated total sediment loads delivered to the Chesapeake Bay by major tributary in 2009.
4-4
December 29, 2010
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Chesapeake Bay TMDL
4.3 POLLUTANT SOURCE SECTOR CONTRIBUTIONS
Table 4-1 and Table 4-2 provide model estimates of major pollutant sources of nitrogen and
phosphorus, respectively, delivered to the Bay by each jurisdiction and by each major pollutant
source sector. Nontidal deposition refers to atmospheric deposition direct to nontidal surface
waters (e.g., streams, rivers). Table 4-3 provides estimates of major sediment sources by
jurisdiction and by major pollutant source sector and represents the portion of sediment that is
from land-based sources. Stream erosion is also a significant source of watershed sediment
delivered to the Bay. Sufficient data do not exist to accurately quantify the portion of the total
sediment load specifically from stream erosion.
Table 4-1. Percentage of total nitrogen delivered to the Bay from each jurisdiction by
pollutant source sector
Jurisdiction
Delaware
District of Columbia
Maryland
New York
Pennsylvania
Virginia
West Virginia
Total
Agriculture
3%
0%
16%
4%
55%
20%
3%
100%
Forest
1%
0%
14%
7%
46%
27%
4%
100%
Stormwater
runoff
1%
1%
28%
3%
33%
33%
2%
100%
Point
source
0%
5%
27%
3%
25%
39%
1%
100%
Septic
2%
0%
36%
5%
30%
24% _j
2%
100%
Nontidal
deposition
1%
0%
27%
5%
42%
25%
1%
100%
Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario
Note: Nontidal deposition refers to atmospheric deposition direct to nontidal surface waters
Table 4-2. Percentage of total phosphorus delivered to the Bay from each jurisdiction by
pollutant source sector
Jurisdiction
Delaware
District of Columbia
Maryland
New York
Pennsylvania
Virginia
West Virginia
Total
Agriculture
4%
0%
19%
5%
24%
42%
6%
100%
Forest
1%
0%
14%
7%
25%
45%
7%
100%
Stormwater
runoff
1%
1%
28%
3%
16%
50%
2%
100%
Point
source
0%
2%
21%
5%
28%
42%
3%
100%
Septic
0%
0%
0%
0%
0%
0%
0%
100%
Nontidal
deposition
0%
0%
27%
5%
27%
38%
2%
100%
Source: Phase 53 Chesapeake Bay Watershed Model 2009 Scenario
Note: Nontidal deposition refers to atmospheric deposition direct to nontidal surface waters. Although the percentage
contribution of phosphorus from nontidal deposition is provided here, the overall amount of phosphorus contributed
from nontidal deposition is considered to be insignificant.
4-5
December 29, 2010
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Chesapeake Bay TMDL
Table 4-3. Percentage of sediment delivered to the Bay from each jurisdiction by
pollutant source sector
Jurisdiction
Delaware
District of Columbia
Maryland
New York
Pennsylvania
Virginia
West Virginia
Total
Agriculture
1%
0%
15%
3%
35%
41%
5%
100%
Forest
0%
0%
13%
8%
34%
40%
5%
100%
Storm water
runoff
1%
1%
32%
4%
21%
39%
3%
100%
Point
source
0%
27%
11%
3%
23%
35%
1%
100%
Septic
--
--
--
--
--
--
--
--
Nontidal
deposition
--
--
-
--
--
--
--
--
Source Phase 53 Chesapeake Bay Watershed Model 2009 Scenario
Note: Only land-based sources of sediment were included in this table Septic sources discharge to groundwater and
nontidal deposition refers to atmospheric deposition direct to nontidal surface waters
The following sections provide additional details regarding the major pollutant source sectors,
including descriptions of the extent/magnitude of the pollutant source, geographic distribution,
and long-term trends relevant to the source sector. The significance of the source sector in terms
of loading to the Bay relative to other sources is also discussed.
4.4 REGULATED POINT SOURCES
Point sources are defined as any "discernable, confined, and discrete conveyance, including...any
pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock, concentrated
animal feeding operation, landfill leachate collection system, or vessel or other floating craft,
from which pollutants are or may be discharged" [CWA section 502(14), 40 CFR 122.2]. That
definition does not include agricultural stormwater discharges or return flows from irrigated
agriculture, which are exempt from the definition of point source under the CWA. The NPDES
program, under CWA sections 318. 402, and 405, requires permits for the discharge of pollutants
from point sources.
Two issues that directly affect modeling of the regulated point sources in the Bay watershed are
the size of facility flows and permitted discharge limits. For purposes of the Chesapeake Bay
TMDL analysis and modeling, regulated point sources in the Chesapeake Bay watershed have
been evaluated under the following categories':
• Municipal wastewater facilities
• Industrial wastewater facilities
• CSOs
• NPDES permitted stormwater (MS4s, industrial, and construction)
• NPDES permitted CAFOs
' The universe of regulated point sources may change over time due to such actions as designation, compliance
evaluation, or new permitting activities.
4-6
December 29, 2010
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Chesapeake Bay TMDL
The remainder of'this section outlines the distinctions between significant and nonsignificant
municipal and industrial wastewater discharge facilities in the Bay watershed, explains how the
facilities were addressed in modeling, discusses the effect of the basinwide nitrogen and
phosphorus permitting approach on point source modeling for the TMDL, and provides a
summary of model-estimated loads associated with each of the regulated point source categories
of nitrogen, phosphorus, and sediment to the Bay. Appendix Q includes the regulated point
sources accounted for in the Bay TMDL.
4.4.1 Significant and Nonsignificant Municipal and Industrial Facilities
Municipal and industrial wastewater discharge facilities are categorized as significant or
nonsignificant primarily on the basis of permitted or existing flow characteristics and comparable
loads in the case of industrial discharge facilities. The Bay jurisdictions define significant
facilities as outlined in Table 4-4.
Table 4-4. Jurisdiction-specific definitions of significant municipal and industrial
wastewater discharge facilities
Jurisdiction
Delaware
District of Columbia
Maryland
New York
Pennsylvania
Virginia
West Virginia
Municipal wastewater facilities
(million gallons per day)
Design flow s 0.4
Blue Plains WWTP
Design flow 2 0.5
Design flow 2 0.4
Existing flow £ 0.4
Design flow s 0.5"
Design flow >0.1b
New facilities £0.04°
Design flow £ 0.4
Industrial wastewater facilities
(estimated loads,
pounds per year)
2 3,800 total phosphorus
or > 27,000 total nitrogen
Source USEPA2010b
Notes: a. Above the fall line/tidal line; b Below the fall line/tidal line; c. Also includes expansion of flows a 0.04 mgd
Jurisdictions also may identify specific facilities as significant in their WIPs (USEPA 2009c).
Facilities not meeting the above criteria, and not otherwise identified in the jurisdictions1 WIPs.
are considered nonsignificant facilities. Table 4-5 provides a jurisdictional breakdown of
municipal and industrial discharging facilities in the Chesapeake Bay watershed.
For the TMDL, facilities were represented using various flow and discharge concentrations
depending on their status as significant or nonsignificant. Significant facilities received
individual WLAs, except for New York and the Virginia James River Basin, which received an
aggregate WLA. The New York WLA for wastewater is discussed further in Section 8.4.4, and
the James River Basin WLA is discussed further in Appendix X. Nonsignificant facilities were
generally included in the aggregate WLAs by Bay segment watershed (USEPA 2009c) and are
discussed further in Section 8.3.3.
4-7
December 29, 2010
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Chesapeake Bay TMDL
Table 4-5. Significant and nonsignificant municipal and industrial wastewater
discharging facilities by jurisdiction as of December 2010
Jurisdiction
DCa
DE
MD
NY
PA
VA
wv*
Total
Significant facility
Municipal
1
3
75
26
183
101
13
402
Industrial
0
1
12
2
30
24
7
76
Total
1
4
87
28
213
125
20
478
Nonsignificant facility
Municipal
1
1
163
26
1246
1618
125
3180
Industrial
9
1
477
45
409
639
23
1603
Total
10
2
640
71
1655
2257
148
4783
Total
Facilities
11
6
727
99
1868
2382
168
5261
Source: Facilities identified in the final phase 1 WIPs
Notes:
a. Blue Plains WWTP serves DC and parts of MD and VA, but is only counted once.
b Multiple facilities (4) share one NPDES permit in West Virginia.
4.4.2 Basinwide NPDES Permitting Approach
In 2004 EPA and the Bay watershed jurisdictions agreed to take a consistent approach to
permitting all the significant municipal and industrial wastewater discharging facilities
contributing nitrogen and phosphorus to the Chesapeake Bay watershed (USEPA 2004d). As part
of that approach and on the basis of the jurisdictions' revised Chesapeake Bay WQS, permits are
to be reissued with nitrogen and phosphorus limits that are sufficient to achieve Bay WQS and
that are consistent with the jurisdictions' tributary strategies. The basinwide permitting approach
also contains additional specific provisions for permitting of nitrogen and phosphorus in the Bay
watershed, including the following:
• Annual load limits—Unless such expressions would be impracticable, EPA's regulations
require NPDES permits for non-publicly owned treatment works to express effluent limits
as maximum daily and average monthly limits [40 CFR I22.45(d)(l)] and require NPDES
permits for POTWs to express effluent limits as average weekly and average monthly
limits [40 CFR I22.45(d)(2)]. In the case of the Chesapeake Bay permitting for nitrogen
and phosphorus, EPA has determined that because of the long hydraulic durations in the
Bay, and the fact that the control of annual loading levels of nitrogen and phosphorus from
wastewater treatment plants is much more relevant and appropriate in terms of the effect of
nitrogen and phosphorus on Bay water quality criteria than daily maximums or weekly or
monthly averages, expression of nitrogen and phosphorus effluent limits in short periods is
impracticable and that, therefore, such effluent limits may be expressed as an annual load
(USEPA 2004c).
• Compliance Schedules—Compliance schedules that are consistent with jurisdiction
tributary strategies may be incorporated into permits, where such compliance schedules are
needed, appropriate, and allowable under jurisdiction WQS and federal NPDES
requirements (USEPA 2004d).
• Watershed permits/trading—Watershed permits, which may accommodate nitrogen and
phosphorus trading, may be used if such an approach would ensure protection of applicable
4-8
December 29, 2010
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Chesapeake Bay TMOL
jurisdiction WQS and would be consistent with existing EPA policy regarding trading
(USEPA 2004d).
In 2005 the seven Bay jurisdictions began implementing the new permitting approach. As of
June 2010, the permits for the significant nitrogen and phosphorus sources have been issued with
nitrogen and phosphorus limits consistent with the Tributary Strategy allocations (described in
Section 1.2.1) (some of which may include compliance schedules) to 64 percent of the
significant wastewater treatment facilities (305 out of the total 478), accounting for 74 percent of
the total design flow. 76 percent of the total nitrogen loads and 91 percent of the total phosphorus
loads from significant facilities (fable 4-6).
By the end of 2011, EPA expects all 478 significant wastewater treatment facilities in the Bay
watershed to have annual nitrogen and phosphorus load limits in place in their permits (some of
which may have compliance schedules as well).
Table 4-6. Nitrogen and phosphorus permit tracking summary under the Basinwide
NPDES Wastewater Permitting Approach, through December 2010
Jurisdiction
DCa
DE
MD
NY
PA
VA
vw"
Total
Significant
facility
NPDES
1
4
87
28
213
125
20
478
Permits
drafted
1
4
72
1
141
125
16
364
Permits
issued
1
4
51
1
103
125
16
305
Design flow of
facilities
permits
issued
152.5
3.3
357.7
20.0
434.1
1,253.5
27.737
2,259.7
Percent of design
flow for permits
issued/significant
facilities
100%
100%
42%
22%
67%
100%
100%
74%
Source: USEPA Region 3, Region 2, Facilities identified in the final Phase 1 WIPs
Notes
Some industrial design flows are not available or not comparable and not listed in the database. Some permits may
contain compliance schedules
a Blue Plains WWTP serves DC and parts of MD and VA, but is only counted once
b. Multiple facilities (4) share one NPDES permit in West Virginia.
4.5 REGULATED POINT SOURCE LOAD SUMMARIES
This section presents load estimates for each major point source sector.
4.5.1 Municipal Wastewater Discharging Facilities
A municipal wastewater facility is defined as a facility discharging treated wastewater from
municipal or quasi-municipal sewer systems. EPA identified 3,582 NPDES permitted facilities
as discharging municipal wastewater into the Chesapeake Bay watershed. Table 4-7 provides a
summary of municipal wastewater facilities by jurisdiction; a complete list is available in
Appendix Q.
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December 29, 2010
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Chesapeake Bay TMDL
Table 4-8 and Table 4-9 summarize modeled 2009 municipal wastewater loading estimates by
jurisdiction and major river basin, respectively, for total nitrogen and phosphorus loads delivered
to the Chesapeake Bay. Modeled sediment loads for those facilities are not presented because
wastewater discharging facilities represent a de minimis source of sediment (i.e., less than 0.5
percent of the 2009 total sediment load). In 2009 municipal wastewater treatment facilities
contributed an estimated 17 percent of the total nitrogen and 16 percent of the total phosphorus
loads delivered to Chesapeake Bay.
Table 4-7. Municipal wastewater facilities by jurisdiction
Jurisdiction
DC
DE
MD
NY
PA
VA
WV
Total
Significant
1
3
75
26
183
101
13
402
Nonsignificant
1
1
163
26
1246
1618
125
3180
Source: EPA Region 3, EPA Region 2
Note: Blue Plains wastewater treatment plant serves DC and portions of Maryland and Virginia but is counted once in
this table as a DC plant.
Table 4-8. Model estimated 2009 municipal wastewater loads by jurisdiction delivered to
Chesapeake Bay
Jurisdiction
DC
DE
MD
NY
PA
VA
VW
Total
Flow
(mgd)
140
2
563
62
335
585
13
1,698
Total nitrogen delivered
(Ib/yr)
2,387,918
42,529
11,928,717
1,360,684
9,391,741
16,926,806
188,137
42,226,535
Total phosphorus delivered
(Ib/yr)
20,456
4,984
568,905
159,096
740,397
1,047,998
62,674
2,604,509
Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario
Table 4-9. Model estimated 2009 municipal wastewater loads by major river basin
delivered to Chesapeake Bay
Basin
Susquehanna River
MD Eastern Shore
MD Western Shore
Hatuxent River
Potomac River
Rappahannock River
York River
James River
VA Eastern Shore
Total
Flow
(mgd)
383
25
254
58
635
23
20
299
<1
1,698
Total nitrogen delivered
(Ibs/yr)
10,556,831
696,872
7,279,406
640,507
9,475.644
376.453
691,550
12,494,335
14,937
42,226,535
Total phosphorus delivered
(Ibs/yr)
835,426
70,540
331,362
61,948
412,464
46,463
45,012
798,615
2,679
2,604,509
Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario
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December 29, 2010
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Chesapeake Bay TMDL
Figure 4-7 and Figure 4-8 illustrate the prevalence and locations of significant and nonsignificant
municipal \vastewater discharge facilities, respectively, across the watershed.
Significant Municipal Facility
(millions gallons/day)
• *2
• 2-10
10-as
• 25-50
• >&0
Source: Phase 5 3 Chesapeake Bay Watershed Model 2009 Scenario
Figure 4-7. Significant wastewater treatment facilities in the Chesapeake Bay watershed.
4-11
December 29, 2010
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Chesapeake Bay TMDL
Nonsignificant Municipal Facilitiet
Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario
Figure 4-8. Nonsignificant municipal wastewater treatment facilities in the Chesapeake Bay watershed.
Data related to municipal and industrial facilities are in the Bay Watershed Model point source
database maintained by the CBP and include information for the 478 significant industrial,
municipal, and federal facilities discharging directly to the surface waters in the watershed. The
wastewater data used to calibrate the Bay Watershed Model cover the 1984 to 2005 time frame and
ire updated annually as data become available. Data are largely supplied by the seven watershed
4-12
December 29, 2010
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Chesapeake Bay TMDL
jurisdictions but are also obtained from NPDES permit databases, including EPA's Permit
Compliance System (PCS) and jurisdiction discharge monitoring reports (DMRs). For each facility
outfall, the database includes monthly flow and monthly average concentrations for total nitrogen.
ammonia, nitrate and nitrite, total organic nitrogen, total phosphorus, orthophosphate. total organic
phosphorus, total suspended solids, biological oxygen demand, and DO.
Because the Bay jurisdictions are required to submit monthly concentration and flow data to
KPA for only significant dischargers, the Bay Watershed Model point source database does not
include comprehensive information useful for characterizing the nonsignificant facilities
(especially nonsignificant industrials) for the Bay TMDL. For nonsignificant municipal facilities,
all Bay jurisdictions conducted a one-time data collection in 2008 for the nitrogen and
phosphorus discharge data, and estimates are based on any available data sources and default
values recommended in Chesapeake Bay Watershed Model Application and Calculation of
Nutrient and Sediment Loadings Appendix F: Phase IV Chesapeake Bay Watershed Model
Point Source Load (CBP 1998). EPA supplemented this information by querying the Integrated
Compliance Information System database (ICIS) for jurisdictions that have migrated to ICIS as
of 2009 (District of Columbia, Maryland, Pennsylvania, and New York), querying the PCS
database for jurisdictions that have not yet migrated to ICIS (Delaware, Virginia and West
Virginia), and obtaining Maryland and Virginia facility information directly from Maryland
Department of the Environment (MDE) and Virginia Department of Environmental Quality
(VADEQ), respectively.
For more information regarding the data used to represent municipal wastewater discharge
facilities and how they were incorporated into modeling for the TMDL, see Section 7 of the Bay
Watershed Model documentation at
http://www.chesapeakebay. net/model jjhase5.aspx?menuitem=26169
Appendix Q provides facility-specific information including NPDES ID. location, and more for
all wastewater dischargers accounted for in the Bay TMDL.
4.5.2 Industrial Discharge Facilities
Industrial discharge facilities are facilities discharging process water, cooling water, and other
contaminated waters from industrial or commercial sources. EPA identified 1.679 NPDES
permitted facilities discharging industrial wastewaters in the Chesapeake Bay watershed (Table
4-10, Appendix Q), with 76 significant facilities (Figure 4-9) and 1,603 nonsignificant facilities
(Figure 4-10). In 2009 industrial wastewater discharging facilities contributed an estimated 7.3
million pounds of the total nitrogen and 1.27 million pounds of the total phosphorus loads
delivered to Chesapeake Bay (Table 4-11 and Table 4-12) an estimated 3 percent and 8 percent,
respectively, of all nitrogen and phosphorus loads delivered to the Chesapeake Bay.
Table 4-12 summarizes modeled wastewater nitrogen and phosphorus loading estimates using
2009 loading conditions. Modeled sediment loads for industrial or commercial facilities are not
presented because their wastewater discharges represent a de niinimis source of sediment (i.e.,
less than 0.5 percent of the 2009 total sediment load).
4-13 December 29, 2010
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Chesapeake Bay TMDL
Table 4-10. Industrial wastewater facilities
Jurisdiction
DC
DE
MD
NY
PA
VA
WV
Total
Significant
0
1
12
2
30
24
7
76
Nonsignificant
9
1
477
45
409
639
23
1,603
Source: USEPA Region 3, Region 2
Table 4-11. 2009 Load estimates of industrial facility discharges
Jurisdiction
DC
DE
MD
NY
PA
VA
WV
Total
Flow
(mgd)
13
<1
48
7
179
160
14
422
Total nitrogen delivered
(Ibs/yr)
183,490
95,438
1,989,243
126,897
2,010,639
2,883,828
55,213
7,344,748
Total phosphorus delivered
(Ibs/yr)
20,433
71
267,093
19,971
260,140
649,266
53,592
1,270,566
Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario
Table 4-12. 2009 Flow, total nitrogen, and total phosphorus load estimates of industrial
wastewater facility discharges by major river basin
Basin
Susquehanna River
MD Eastern Shore
MD Western Shore
Patuxent River
Potomac River
Rappahannock River
York River
James River
VA Eastern Shore
Total
Flow
(mgd)
184
5
21
3
71
5
81
51
1
422
Total nitrogen delivered
(Ibs/yr)
2,171,197
302,210
1,369,383
50,615
779,885
78,006
478,892
1,979,297
135,211
7,344,697
Total phosphorus delivered
(Ibs/yr)
281,922
45,626
105,100
38,689
420,997
36,039
81,675
259,331
1,160
1,270,539
Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario
4-14
December 29, 2010
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Chesapeake BayTMDL
Significant Industrial facilities
Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario
Figure 4-9. Significant industrial wastewater discharge facilities in the Chesapeake Bay watershed.
4-15
December 29, 2010
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Chesapeake Bay TMDL
• Non-Significant industrial Facilities
Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario
Figure 4-10. Nonsignificant industrial wastewater discharge facilities in the Chesapeake Bay watershed.
4-16
December 29, 2010
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Chesapeake Bay TMDL
Discharge Monitoring Report (DMR) data from the population of industrial facilities were used
to derive loadings where available. The majority of nonsignificant industrial facilities do not
have DMR data for nitrogen and phosphorus. However, the default values from typical pollutant
concentrations (Tetra Tech 1999) were used to estimate the loads where DMR data are not
available, except for power plants and other facilities with high flows.
Industrial facilities, such as power plants, petroleum refineries, and steel mills, that were not on
the significant facility list were considered as high-flow, nonsignificant facilities in the
evaluation. Nitrogen and phosphorus loads resulting from the use of flue gas desulfurization
units, effluent from coal ash ponds and biocide applications at high-flow facilities were estimated
from available databases. Data sets queried include EPA's PCS and ICIS permit systems, 316(b)
cooling water intake structure regulation data, U.S. Department of Energy's Energy Information
Administration data, and EPA's eGrid database.
Thirty-two power plants were identified as being in the Chesapeake Bay watershed. Eight of
those facilities use cooling towers as part of their cooling system. Of the 32 facilities, 18 use coal
as a fuel source; 7 use a flue gas desulfurization, and 13 use ash ponds. Eighty-nine other high-
flow industrial sites were identified in the watershed and represent a variety of industrial
activities.
Pollutant loads were estimated for the eight facilities that use cooling towers. The PCS and ICIS
databases were queried for blowdown flows, and cooling tower chemical vendors were consulted
to estimate water quality conditions in the towers. Facility use rates were then obtained from
EPA's eGrid database to characterize utilization routines and variability in blowdown events.
Similarly, flue gas desulfurization and ash pond loads were estimated using data obtained from
the PCS and ICIS databases.
4.5.3 Combined Sewer Overflows
Combined sewer systems (CSS) are sewers that are designed to collect rainwater runoff,
domestic sewage, and industrial wastewater in the same pipe. Normally, the systems transport
wastewater to a treatment plant, where it is treated and discharged to surface waters. However,
during heavy rainfall or snowmelt, flow volumes in a CSS can exceed the capacity of the sewer
system or treatment plant. To avoid situations where excess flows overwhelm the sewer network
or the treatment capacity of the treatment system, CSSs are designed to overflow during times of
high volume, discharging untreated excess wastewater directly to nearby streams, rivers, or other
waterbodies.
Such overflows, called combined sewer overflows (CSOs), contain stormwater and untreated
human and industrial waste, toxic materials, and debris. There are 64 CSO communities in the
Chesapeake Bay watershed (Table 4-13 and Figure 4-11).
4-17 December 29, 2010
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Chesapeake BayTMDL
Table 4-13. Combined sewer system communities in the Bay watershed
Jurisdiction
DC
DE
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
NY
NY
NY
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
River basin
Potomac
Eastern Shore
Eastern Shore
Eastern Shore
Potomac
Patapsco
Eastern Shore
Eastern Shore
Potomac
Potomac
Potomac
Potomac
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
NPDES ID
DC0021199
DE0020265
MD0020249
MD0021571
MD0021598
MD0021601
MD0021636
MD0022764
MD0067384
MD0067407
MD0067423
MD0067547
NY0023981
NY0024406
NY0035742
PA0020940
PA0021237
PA0021539
PA0021571
PA0021687
PA0021814
PA0022209
PA0023248
PA0023558
PA0023736
PA0024341
PA0024406
PA0026107
PA0026191
PA0026310
PA0026361
PA0026492
PA0026557
PA0026743
PA0026921
PA0027014
PA0027022
PA0027049
PA0027057
PA0027065
PA0027081
PA0027090
PA0027197
PA0027324
PA0028631
Facility name
Washington, District of Columbia
Seaford Waste Treatment Plant
Federalsburg WWTP
City of Salisbury WWTP
Cumberland WWTP
Patapsco WWTP
Cambridge WWTP
Snow Hill Water & Sewer Department
Westernport CSO
Allegany County CSO
Frostburg CSO
Lavale Sanitary Commission CSO
Johnson City (V) Overflows
Binghamton (C) CSO
Chemung Co Elmira SD STP
Tunkhannock Boro Municipal Authority
Newport Boro STP
Williamsburg Municipal Authority
Marysville Borough WWTP
Wellsboro WWTP
Mansfield Boro WWTP
Bedford WWTP
Berwick Area Joint Sewer Authority WWTP
Ashland WWTP
Tri-Boro Municipal Authority WWTP
Canton Boro Auth. WWTP
Mount Carmel WWTF
Wyoming Valley Sanitary Authority WWTP
Huntingdon Borough WWTP
Clearfleld Mun. Auth. WWTP
Lower Lackawanna Valley Sanitary Authority WWTP
Scranton Sewer Authority WWTP
Sunbury City Municipal Authority WWTP
Lancaster City WWTP
Greater Hazelton Joint Sewer Authority WWTP
Altoona City Auth. - Easterly WWTP
Altoona City Auth. - Westerly WWTF
Williamsport Sanitary Authority - West Plant
Williamsport Sanitary Authority - Central Plant
LRBSA - Archbald WWTP
LRBSA - Clinton WWTP
LRBSA - Throop WWTP
Harrisburg Advanced WWTF
Shamokin Coal Twp Joint Sewer Authority
Mid-Cameron Authority
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December 29, 2010
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Chesapeake Bay TMDL
Jurisdiction
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
VA
VA
VA
VA
WV
WV
WV
WV
WV
River basin
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
Susquehanna
James
James
James
Potomac
Potomac
Potomac
Potomac
Potomac
Potomac
NPDES ID
PA0028673
PA0036820
PA0037711
PA0038920
PA0043273
PA0046159
PA0070041
PA0070386
PAG062202
PAG063501
VA0063177
VA0024970
VA0025542
VA0087068
WV0020150
WV0021792
WV0023167
WV0024392
WV01 05279
Facility name
Gallitzin Borough Sewer and Disposal Authority
Galeton Borough Authority WWTP
Everett Area WWTP
Burnham Borough Authority WWTP
Hollidaysburg STP
Houtzdale Boro Municipal Sewer Authority
Mahanoy City Sewer Authority WTP
Shenandoah Municipal Sewer Authority WWTP
Lackawanna River Basin Sewer Authority.
Steelton Boro Authority
Richmond
Lynchburg
Covington Sewage Treatment Plant
Alexandria
City of Moorefield
City of Petersburg
City of Martinsburg
City of Keyser
City of Piedmont
CSOs are considered point sources and are assigned WLAs in this TMDL. EPA's CSO Control
Policy is the national framework for implementing controls on CSOs through the NPDES
permitting program. The policy resulted from negotiations among EPA, municipal organizations,
environmental groups, and state agencies. It provides guidance to municipalities and state and
federal permitting authorities on how to meet the CWA's pollution control goals as flexibly and
cost-effectively as possible. The CSO policy was published in the Federal Register (FR) (59 FR
18688, April 19, 1994). CSO communities are required to develop Long-Term Control Plans
(LTCPs), detailing steps necessary to achieve full compliance with the CWA.
EPA relied on various sources of information to characterize the prevalence of CSOs in the Bay
watershed and to quantify their loads for the Bay TMDL. There are 64 CSO communities in the
Bay watershed (Table 4-13). Overflow volume and pollutant loading from CSO communities are
heavily dependent on the service area or catchment area of the combined system. Service area
data obtained from the communities were used to calculate the loading from each community
during high-flow events. Precipitation data observations were also obtained from weather
monitoring stations proximate to each community to derive runoff volumes. Estimates of
overflows and associated pollutant loads from CSO communities were then developed using
various sources of water quality data including monitoring data and literature values.
4-19
December 29, 2010
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Chesapeake Bay TMDL
Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario
Figure 4-11. CSO communities in the Chesapeake Bay watershed.
4-20
December 29, 2010
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Chesapeake Bay TMDL
For four of the largest CSO communities in the watershed—Alexandria, Virginia; Lynchburg.
Virginia; Richmond, Virginia; and the District of Columbia—EPA relied heavily on readily
available and relatively detailed LTCPs to characterize overflows. In addition, EPA ran
simulations of existing sewer models for those communities to support developing overflow and
water quality estimates. EPA used the District of Columbia's CSS model to develop loading
estimates for the CSOs. For the Alexandria, Richmond, and Lynchburg CSSs, various versions
of EPA's Storm Water Management Model (SWMM) were used to estimate overflows. CSO
discharge monitoring data were available for the Alexandria and Richmond CSSs, but no
samples were available from Lynchburg because the LTCP calls for complete separation of this
system (i.e.. separation of the storm sewers from sanitary sewers).
Information related to loading from the other 60 CSO communities in the watershed includes
spatial data collected as a result of a direct survey of the communities to support the TMDL.
limited water quality and overflow data from some of the CSO communities in the watershed,
and representative water quality concentrations available in the literature. For further information
regarding the data used to estimated CSO loads, see Section 7 of the Chesapeake Bay Watershed
Model documentation at http://w ww .chesapeakebay.net/model phase5.aspx?menuitem=26169.
To avoid the difficulty of measuring LTCP implementation progress with weather-dominated
CSO loading estimates, EPA used the 10-year average CSO loads for 1991-2000, which
correlates with the hydrologic period selected for the TMDL (see Section 6.1.1). The loads from
that 10-year period were used as the baseline to assess CSO progress and WLAs. Any CSO
implementation progress will be tracked and input in the model as a reduction factor to represent
a reduction achieved from the baseline. Thus, any reduction will be from management actions
only and not from climate variation. The CSS land use will be changed to urban area for
stormwater simulation in the model if there is CSS separation in the implementation plan and the
separation acreage is reported with the reduction factor for implementation progress tracking.
4.5.4 Sanitary Sewer Overflows
Properly designed, operated, and maintained sanitary sewer systems are meant to collect and
transport all the sewage that flows into them to a WWTP. SSOs are illegal discharges of raw
sewage from municipal sanitary sewer systems. Frequent SSOs are indicative of problems with a
community's collection system and can be due to multiple factors:
• Infiltration and inflow contributes to SSOs when rainfall or snowmelt infiltrates through
the ground into leaky sanitary sewers or when excess water flows in through roof drains
connected to sewers, broken pipes, or badly connected sewer service lines. Poor service
connections between sewer lines and building service lines can contribute as much as 60
percent of SSOs in some areas.
• Undersized systems contribute to SSOs when sewers and pumps are too small to carry
sewage from newly developed subdivisions or commercial areas.
• Pipe failures contribute to SSOs as a result of blocked, broken, or cracked pipes; tree roots
growing into the sewer; sections of pipe settling or shifting so that pipe joints no longer
match; and sediment and other material building up causing pipes to break or collapse.
• Equipment failures contribute to SSOs because of pump failures or power failures.
4-21 December 29, 2010
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Chesapeake Bay TMDL
SSOs represent a source of nitrogen and phosphorus to the Chesapeake Bay; however,
information available to characterize their contribution to the overall nitrogen and phosphorus
loads delivered to the Bay is limited largely because of their illegality and infrequency. Although
the Bay Watershed Model does not specifically account for SSOs, the nitrogen and phosphorus
load contributions from SSOs are part of the background conditions incorporated into the Phase
5.3 watershed model and. therefore, such loads are accounted for in the data used for calibration
of the Bay Watershed Model. Because SSOs are illegal, however, the Chesapeake Bay TMDL
assumes full removal of SSOs and makes no allocation to them.
4.5.5 NPDES Permitted Stormwater
Urban and suburban stormwater discharges contain nitrogen, phosphorus, and sediment from
sources such as pet wastes, lawn fertilizers, construction activity, impervious surfaces, and air
contaminants. The in-stream bank and bed scouring caused by increased volumes and durations
of stormwater discharges contribute additional sediment and nitrogen and phosphorus loads to
the Bay and its tributaries. Those nitrogen, phosphorus, and sediment loads affect local water
quality, habitats, and the Bay downstream and represent a significant proportion of nitrogen,
phosphorus, and sediment loads to Bay. The CBP estimates that in 2009 stormwater from urban
and suburban development contributed to 16 percent of the sediment loadings, 15 percent of the
phosphorus loadings, and 8 percent of the nitrogen loadings to the Bay (Bay Watershed Model
2009 Scenario).
Under the federal stormwater regulatory program, three broad categories of stormwater
discharges are regulated (see 40 CFR 122.26, CFR 122.30-37):
• Stormwater discharges from medium and large Municipal Separate Storm Sewer Systems
(MS4s) and small MS4s in Census Bureau defined urbanized areas
• Stormwater discharges associated with construction activity 1 acre and larger
• Stormwater discharges associated with specified categories of industrial activity
In addition, EPA established a process for designating and requiring NPDES permit coverage for
additional stormwater discharges, implementing section 402(p)(2)(E). This residual designation
authority (RDA) of section 402(p)(2)(E) is in 40 CFR 122.26(a)(9)(i)(C) and (D). EPA retains
additional authority in CWA section 402(p)(5) and (6) to designate additional point sources of
stormwater.
EPA's intent in creating the MS4 Stormwater Program was to regulate stormwater discharges by
requiring the municipalities to develop management programs to control stormwater discharging
via the MS4, i.e., stormwater collected by the MS4 from throughout its service area.
CWA section 402(p) establishes the framework for EPA to address stormwater discharges. In
Phase I, EPA established NPDES permit requirements for stormwater discharges associated with
• Industrial activity, including construction activity disturbing 5 acres or greater, including
sites smaller than 5 acres if they are associated with a common plan of development or sale
that is at least 5 acres in size
• Discharges from MS4s serving populations of 100,000 or more
4-22 December 29, 2010
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Chesapeake Bay TMDL
In Phase II, EPA established permit requirements for stormwater discharges from
• Construction activity disturbing 1 to 5 acres, including sites smaller than 1 acre if they are
associated with a common plan of development or sale that is at least 1 acre in size
• Small MS4s serving populations of fewer than 100,000 in urbanized areas
With respect to Phase II MS4s, EPA considers stormwater discharges from within the geographic
boundary of the urbanized area (and designated areas) served by small MS4s to be regulated (64
FR 68722, 68751-52 and 68804, Appendix 2, December 8, 1999). The reason for regulating
small MS4s in urbanized areas was based on the correlation between the degree of development/
urbanization and adverse water quality impacts from stormwater discharged from such areas.
EPA can and has designated additional stormwater discharges, such as those from impervious
surfaces above a certain size threshold, using its residual designation authority under 40 CFR
122.26(a)(9)(i)(C) and (D). At the discretion of the NPDES permitting authority, stormwater
dischargers that require NPDES permits can either obtain individual permits or, with the
exception of medium and large MS4s, obtain coverage under general permits (see 40 CFR
122.28). Also, EPA has additional authority in CWA section 402(p)(5) and (6) to designate
additional point sources of stormwater.
Figure 4-12 shows the locations of Phase I and II MS4s in the Bay watershed.
Unless stormwater discharges are identified in EPA's Phase I or Phase II regulations or are
designated pursuant to CWA section 402(p)(2)(E) or 402(p)(6), the discharges are not regulated
under CWA section 402. As explained in EPA guidance, "stormwater discharges that are
regulated under Phase I or Phase II of the NPDES stormwater program are point sources that
must be included in the WLA portion of a TMDL" (USEPA 2002). Appendix Q includes the
stormwater permits subject to this Bay TMDL.
It is estimated that existing NPDES MS4 areas contributed approximately 7,027,362 Ibs total
nitrogen, 900,868 Ibs total phosphorus, and 287,295 tons of sediment annually in 2009. That
compares to the total load delivered annually to the Bay of 251,040,081 Ibs total nitrogen,
16,619,332 Ibs total phosphorus and 4,000,118 tons sediment by all sources (Bay Watershed
Model 2009 Scenario).
The contribution from industrial stormwater discharges subject to NPDES permits has been
estimated on the basis of data submitted by jurisdictions in their Phase I WIPs, including the
number of industrial stormwater permits per county and the number of urban acres regulated by
industrial stormwater permits. For the Bay TMDL, the permitted industrial stormwater load is
subtracted from the MS4 load when applicable. Table 4-14 provides an accounting of the current
individual and general stormwater NPDES permits issued within the Chesapeake Bay watershed.
4-23 December 29, 2010
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Chesapeake Bay TMDL
Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario
Figure 4-12. Phase I and II MS4s in the Chesapeake Bay watershed.
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December 29, 2010
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Chesapeake Bay TMDL
Table 4-14. NPDES stormwater permittees by jurisdiction and in the Chesapeake Bay
watershed, summer 2009
Jurisdiction
DC
DE
MO
NY
PA
VA
VW
Total
Baywide
Districtwide
Baywide
Statewide
Baywide
Statewide
Baywide
Statewide
Baywide
Statewide
Baywide
Statewide
Baywide
Statewide
Bay
States
NPDES Stormwater permit type
MM
Phase I
1
1
1
14
11
11
0
1
0
2
11
11
0
0
23
40
MS4
Phase II
0
0
0
3
82
82
34
502
206
727
75
90
3
45
400
1,449
Industrial
60
60
48
337
1,578
1,578
122
1,393
1,238
2,494
975
1,432
113
933
4,086
8,227
Construction
212
212
NA*
1,375
8,300
8,332
470
7,251
906
2,399
2,252
2,851
651
2,488
12,791
24,908
Total
273
273
49
1,729
9,971
10,003
626
9,147
2,350
5,622
3,313
4,384
767
3,466
17,300
34,624
%
Permittees
in the Bay
1 6%
0.3%
57.6%
3.6%
13.6%
19.2%
4.4%
100%
Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario
Note Numbers of permittees are not static, and especially for categories like construction are fluctuating regularly.
* Not including Delaware
Data used to characterize loads from regulated stormwater activities and to represent these
sources in the model are available from the jurisdictions' NPDES programs and from EPA
Region 3's NPDES permitting, the permitting authority in the District of Columbia and for
federal facilities in Delaware. Details related to how loads for MS4s and NPDES-permitted
construction and industrial stormwater activities were derived for the Bay TMDL are in Section
7 of the Phase 5 Chesapeake Bay Watershed Model documentation at
http://www.chesapeakebav.net/modeLphase5.aspx?menuitem=26169.
4.5.6 Concentrated Animal Feeding Operations
The NPDES program regulates the discharge of pollutants from point sources to waters of the
United States. Concentrated Animal Feeding Operations (CAFOs) are included in the definition
of point sources in CWA section 502(14). To be considered a CAFO, a facility must first be
defined as an AFO.
AFOs are agricultural operations where animals are kept and raised in confined situations. AFOs
generally congregate animals, feed, manure, dead animals, and production operations on a small
land area. Feed is brought to the animals rather than the animals grazing or otherwise seeking
feed in pastures. Such operations are defined as AFOs if animals are confined for 45 or more
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Chesapeake Bay TMDL
days per year in facilities where vegetation and other growth are not present during the normal
growing season [40 CFR 122.42(b)(l)].
AFOs that meet the regulatory definition of a CAFO or that are designated as a CAFO are
regulated under the NPDES permitting program and are required to seek NPDES permit
coverage if they discharge or propose to discharge. The NPDES regulations define AFOs as
CAFOs based primarily on the number of animals confined (Table 4-15) (for example, a large
dairy CAFO confines 700 or more dairy cattle) [40 CFR 122.23(b)(2), (4), and (6)]. An AFO that
is not defined as a CAFO may be designated as a CAFO if it meets certain conditions [40 CFR
122.23(c)].
Table 4-15. Federal numeric thresholds for small, medium, and large CAFOs
Animal sector
Cattle or cow/calf pairs
Mature dairy cattle
Veal calves
Swine (weighing over 55 pounds)
Swine (weighing less than 55 pounds)
Horses
Sheep or lambs
Turkeys
Laying hens or broilers (liquid manure handling
systems)
Chickens other than laying hens (other than a
liquid manure handling systems)
Laying hens (other than a liquid manure
handling systems)
Ducks (other than a liquid manure handling
systems)
Ducks (liquid manure handling systems)
Size thresholds
(number of animals)
Large CAFOs
1,000 or more
700 or more
1,000 or more
2,500 or more
10,000 or more
500 or more
10,000 or more
55,000 or more
30,000 or more
125,000 or more
82,000 or more
30,000 or more
5,000 or more
Medium CAFOs
300-999
200-699
300-999
750-2,499
3,000-9,999
150-499
3,000-9,999
16,500-54,999
9,000-29,999
37,500-124,999
25,000-81,999
10,000-29,999
1,500-4,999
Small CAFOs
less than 300
less than 200
less than 300
less than 750
less than 3,000
less than 1 50
less than 3,000
less than 16,500
less than 9,000
less than 37,500
less than 25,000
less than 10,000
less than 1,500
Source: 40 CFR 122.23(b)
Under federal regulations, NPDES permits for CAFOs require CAFOs to implement the terms of
a site-specific nutrient management plan (NMP) that includes a number of critical minimum
elements [40 CFR 122.42(e)(l)]. Those requirements limit nitrogen and phosphorus loads from
the production area as well as from the land application area, where manure, litter and process
wastewater must be applied in accordance with site-specific practices to ensure that nitrogen and
phosphorus in the manure will be used appropriately. NPDES permits for all CAFOs must
include technology-based effluent limits in accordance with 40 CFR 122.44. Permitted Large
CAFOs that land-apply manure, litter or process wastewater must comply with technology-based
effluent limitations for land application per the effluent limitations guidelines (ELGs) at 40 CFR
412 (C) and (D). Unpermitted Large CAFOs may not have any discharges except for agricultural
stormwater discharges from the land application area.
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Agricultural stormwater discharges are the precipitation-related discharges from CAFO land
application areas where the CAFO land applies manure, litter or process wastewater in
accordance with nutrient management practices "that ensure appropriate agricultural utilization
of the nutrients in the manure, litter or process wastewater" applied to the land—i.e., for
permitted CAFOs, the terms of an NMP concerning land application [40 CFR 122.23(e)(l)].
State technical standards are used in calculating the technology-based effluent limits in NPDES
permits of Large CAFOs. Requirements for land application areas at small and medium CAFOs
are based on the best professional judgment of the permit writer, and may also incorporate state
technical standards. The agricultural stormwater exemption does not apply to a CAFO's
production area. As a nonpoint source, an agricultural stormwater discharge is not subject to
NPDES permitting requirements or water quality-based effluent limitations (WQBELs).
Any permit issued to a CAFO of any size must include a requirement to implement an NMP that
contains, at a minimum, BMPs that meet the requirements specified in 40 CFR 122.42(e)(l).
These include the following:
• Ensuring adequate storage of manure, litter, and process wastewater, including procedures
to ensure proper operation and maintenance of the storage facility.
• Managing mortalities to ensure that they are not disposed of in a liquid manure,
stormwater, or process wastewater storage or treatment system that is not specifically
designed to treat animal mortalities.
• Ensuring that clean water is diverted, as appropriate, from the production area.
• Preventing direct contact of confined animals with waters of the United States.
• Ensuring that chemicals and other contaminants handled on-site are not disposed of in any
manure, litter, process wastewater, or stormwater storage or treatment system unless
specifically designed to treat such chemicals and other contaminants.
• Identifying appropriate site-specific conservation practices to control runoff of pollutants to
waters of the United States.
• Identifying protocols for appropriate testing of manure, litter, process wastewater, and soil.
• Establishing protocols to land apply manure, litter, or process wastewater in accordance
with site-specific nutrient management practices that ensure appropriate agricultural
utilization of the nutrients in the manure, litter or process wastewater.
• Identifying specific records that will be maintained to document the implementation and
management of the minimum elements described above.
EPA and the jurisdictions have estimated the number of state or federal permitted CAFOs in the
Chesapeake Bay watershed, in part, on the basis of the jurisdictions' respective final Phase I
WIPs(Table4-16).
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Chesapeake Bay TMDL
Table 4-16. Estimated number of state or federal permitted CAFOs
Jurisdiction
Delaware3
Maryland3
New York
Pennsylvania
Virginia
West Virginia
Total
# State or federal
permitted CAFOs
165
365
65
325
30
30
980
Sources: State data submitted to EPA for the Senate Environment and Public Works Committee Hearing on the
Chesapeake Bay on April 20, 2009, and EPA Office of Wastewater Management's latest NPDES CAFO Rule
Implementation Status quarterly national CAFO number update http //www.epa qov/npdes/Dubs/tracksum1Q10 pdf.
Note:
a The numbers of CAFOs in Maryland and Delaware with permits are estimated according to the number of Notices
of Intent (NOIs) received as a result of the EPA February 2009 permit application deadline The NOIs are being
reviewed for permit requirement completeness
4.6 NONPOINT SOURCES
The term nonpoint source means any source of water pollution that does not meet the legal
definition of point source (see Section 4.5). Nonpoint source pollution generally results from
land runoff, precipitation, atmospheric deposition, drainage, seepage, or hydrologic modification.
For purposes of the Chesapeake Bay TMDL analysis and modeling, nonpoint sources in the
Chesapeake Bay watershed have been evaluated under the following categories:
• Agriculture (manure, biosolids, chemical fertilizer)
• Atmospheric deposition
• Forest lands
• On-site wastewater treatment systems (OSWTSs)
• Nonregulated stormwater runoff
• Oceanic inputs
• Streambank and tidal shoreline erosion
• Tidal resuspension
• Wildlife
For the Bay TMDL, Scenario Builder was used to provide the land use-based scenario inputs to
the Bay Watershed Model including forest lands, OSWTSs , nonregulated stormwater runoff,
oceanic inputs, Streambank and tidal shoreline erosion, tidal resuspension, and wildlife (see
Section 5.7). Data sources for agriculture and atmospheric deposition in the Chesapeake Bay
watershed are included in the relevant sections below. Scenario Builder provides estimates of
nitrogen and phosphorus loads to the land and the area of soil available to be eroded. Loads are
input to the Bay Watershed Model to generate modeled estimates of loads delivered to the Bay.
Additional information related to Scenario Builder and its application in Bay TMDL
development (USEPA 201 Od) is at
http://archive.chesapeakebav.net/pubs/SB V22 Final 12 31 20IO.pdf.
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Chesapeake Bay TMDL
4.6.1 Agriculture
Agricultural lands account for 22 percent of the watershed, making agriculture one of the largest
land uses in the area, second only to forested and open wooded areas (69 percent). The Bay
watershed has more than 87,000 farm operations and 6.5 million acres of cropland. However, the
District of Columbia does not include any agricultural lands.
Farms in the Chesapeake Bay watershed produce more than 50 named commodities. The area's
primary crops are pasture, hay, corn, wheat, soybeans, vegetables, and fruits. The eastern part of
the region is home to a rapidly expanding nursery and greenhouse industry.
Animal operations account for more than 60 percent of the region's annual farm product sales. In
the watershed, the six major types of animal operations are dairy cows, beef cattle, pigs, egg
production, broilers, and turkeys. The three major animal production regions in the watershed.
according to livestock concentration, are the lower Susquehanna River in Pennsylvania, the
Shenandoah Valley in Virginia and West Virginia, and the Delmarva Peninsula in Delaware.
Maryland, and Virginia. The Delmarva Peninsula is considered to be one of the country's top
poultry producing regions and, according to the 2002 Census, three Bay counties are among the
top 20 poultry producing counties in the nation (for either poultry/eggs, broilers, or layers):
Sussex County, Delaware; Lancaster County, Pennsylvania; and Wicomico County, Maryland.
In addition, at least one Bay county is among the top 20 counties for production of the following
farm commodities: turkeys; cattle and calves; milk and other cow dairy products; hogs and pigs;
horses and ponies; corn for silage; snap beans; apples; short rotation woody crops; and nursery.
greenhouse, floriculture, and sod.
Agriculture is the largest single source of nitrogen, phosphorus, and sediment loading to the Bay
through applying fertilizers, tilling croplands, and applying animal manure. Agricultural
activities are responsible for approximately 44 percent of nitrogen and phosphorus loads
delivered to the Bay and about 65 percent of sediment loads delivered to the Bay (Bay
Watershed Model 2009 Scenario). Figure 4-13 compares modeled loads from agricultural lands
for 1985 and 2009.
Data sources used to estimate nitrogen, phosphorus, and sediment from agriculture-related
sources include information related to livestock production and manure generation, crop
production and nutrient management, fertilizer use and application, and implementation of
BMPs. EPA in cooperation with the Chesapeake Bay Program's Agricultural Nutrient and
Sediment Reduction Workgroup and Modeling Subcommittee relied on the many sources of
information to characterize loads related to agriculture that are summarized in Section 2 of the
Scenario Builder documentation Estimates of County-Level Nitrogen and Phosphorus Data for
Use in Modeling Pollutant Reduction([)SEP\ 20lOd). Examples of data sources are the U.S.
Department of Agriculture (USDA) Agricultural Census; USDA, state, and university nutrient
management standards and handbooks; peer-reviewed journal articles; agricultural conservation
data from state agricultural and environmental agencies; county agencies, and nongovernmental
organizations; and extensive input from members of the Chesapeake Bay Program's Agricultural
Nutrient and Sediment Reduction Workgroup.
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Chesapeake Bay TMDL
cultural Lc
(Nutrients)
160,000,000
140,000,000
120,000,000
100,000,000
80,000,000
60,000,000
40,000,000
20,000,000
0
Agricultural Loads
(Sediment)
4,000,000
3,500,000
3,000,000
2,500.000
2,000,000
1,500,000
1,000,000
500,000
0
TSS(tons/yr)
Source: Phase 5.3 Chesapeake Bay Watershed Model 1985 and 2009 Scenarios
Figure 4-13.1985 and 2009 modeled total nitrogen, phosphorus, and sediment loads from agricultural lands
across the Chesapeake Bay watershed.
Manure
Animal populations vary across the Bay watershed by animal type and management. Pastures
exist in the watershed for dairy and beef heifers, goats, hogs, and in some places even chickens
and turkeys. Animal feed BMPs are recognized by the Chesapeake Bay watershed model, and
managing manure from production areas can include a suite of BMPs for storage and handling.
Land application of manure is an important nitrogen and phosphorus recycling process in
agriculture. Because manure is so extensively used as a resource of nitrogen and phosphorus, it is
considered as important as inorganic fertilizer and is an important source of nonpoint source
pollution. Figure 4-14 and Figure 4-15 provide historical population data of poultry and non-
poultry animals in the watershed, respectively.
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Chesapeake Bay TMDL
Annual manure production is calculated as a daily excreted amount per animal equivalent unit (1
animal equivalent unit equals 1,000 Ibs live animal weight). Animal units are estimated for
counties on the basis of USDA Agricultural Census data. The total amount of manure produced
is then distributed among the applicable land uses, which include pasture, AFO, and other row
crop land uses. The percentage of time animals spend in pasture (based on state
recommendations) is used to estimate the percentage of total manure produced on pasture lands.
For example, 50 percent pasture time equates to 50 percent of the total manure production
occurring on pasture lands. Manure produced that is associated with time spent confined is
considered to be generated on AFO acres. A fraction of that amount, (15-21 percent depending
on animal type) is assumed to remain on the AFO acres (i.e., not captured by storage and
handling activities), while the rest is redistributed by land application to pasture and row crop
lands. The model simulates AFO acres similarly to urban impervious areas.
Biosolids
Applying biosolids, the nutrient-rich organic materials resulting from treating sewage sludge, as
fertilizer to croplands represents another source of nutrients to the Bay. Biosolids typically
contain plant nutrients (nitrogen, phosphorus, and potassium), although the amount of nutrients
available from biosolids are normally lower than the amounts from most commercial fertilizers
(Huddleston and Ronayne 1990). Nitrogen and phosphorus are the most prevalent nutrients
found in sewage sludge.
60,000.000
so.ooo.ooo •
40,000,000
30.000.000
20,000,000
10,000,000
0
atershed Poultry Populatio
(2007)
DE
MD NY PA
• pullets • turkey* •• broilers • layers
Source: 2007 Agriculture Census
Figure 4-14. 2007 Chesapeake Bay watershed poultry populations by jurisdiction
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Chesapeake Bay TMDL
Watershed Livestock Populations
(2007)
1,000.0
900.'
800,000
700,000
600,000
500,000
400.000
300,000
200,000
100,000
0
II
DE
MD
NY
dairyjieifers
milk_goats
other cattle
• hogs_and_pigs_for_breeding • beef_hiefers
• hogs_for_slaughter • horses
• sheep_and_lambs • angora_goats
Source: 2007 Agriculture Census
Figure 4-15. 2007 Chesapeake Bay watershed livestock populations by jurisdiction.
Regulations governing use, disposal and application of sewage sludge are in EPA's Sewage
Sludge Use or Disposal Regulation (Part 503), which provides a framework for permitting
sewage sludge use or disposal. No jurisdictions in EPA Region 3 have applied for program
authorization of the federal Part 503. Although all Bay jurisdictions have their own sewage
sludge programs in place, only Virginia routinely submits to EPA information regarding land
application of biosolids. As a result, information available to characterize biosolids as a source
and to represent it in the model is limited.
For model characterization, jurisdiction-specific data on biosolids application were used. Land
uses receiving biosolids include crops and pasture/hay, with different monthly proportions based
on seasonal growing patterns. Modeled application rates are the same as manure because
biosolids are applied to land in the same fashion as manure.
For additional information related to representation of biosolids in the Bay TMDL, see the Phase
5.3 Chesapeake Bay Watershed Model documentation at
http://www.chesapeakebav.net/model phase5.aspx?menuitem=26l69
Chemical Fertilizer
Chemical fertilizer application practices across the watershed can be estimated through
commercial sales information. Fertilizer sales data are prepared by the Association of American
Plant Food Control Officials on the basis of fertilizer consumption information submitted by
state fertilizer control offices. The consumption data include total fertilizer sales or shipments for
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December 29, 2010
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Chesapeake Bay TMDL
farm and non-farm use. Liming materials, peat, potting soils, soil amendments, soil additives,
and soil conditioners are excluded. Materials used for the manufacture or blending of reported
fertilizer grades or for use in other fertilizers are excluded to avoid duplicate reporting. A revie\v
of commercial fertilizer sales records (from 1982 to 2007) showed that in all states, the sales are
increasing. The increase can be attributed to both yield increases and increasing application.
Removing the yield increases resulted in persistent increasing trends in chemical fertilizer
nutrient application (except in Maryland where the trend is flat).
Model estimates of commercial fertilizer loads have been derived by back-calculating load from
agricultural lands and determining the proportion of nutrient species applied from commercial
fertilizer, manure, and atmospheric deposition.
As phosphorus-based nutrient management plans increase, the reliance on nitrogen fertilizer is
expected to increase because less manure will be legally permitted to be applied to agricultural
lands. Therefore chemical fertilizers are and will remain a significant potential source of nitrogen
and phosphorus to the Bay.
4.6.2 Atmospheric Deposition
Air sources contribute about one-third of the total nitrogen loads delivered to the Chesapeake
Bay by depositing directly onto the tidal surface waters of Chesapeake Bay and onto the
surrounding Bay watershed. Direct deposition to the Bay's tidal surface waters is estimated to be
6 to 8 percent of the total (air and non-air) nitrogen load delivered to the Bay. The nitrogen
deposited onto the land surface of the Bay's watershed and subsequently transported to the Bay
is estimated to account for 25 to 28 percent of the total nitrogen loadings delivered to the Bay.
Atmospheric loads of nitrogen are from chemical species of oxidized nitrogen, also called NOx.
and from reduced forms of nitrogen deposition, also called ammonia (NH4+). Oxidized forms of
nitrogen deposition originate from conditions of high heat and pressure and are formed from
inert diatomic atmospheric nitrogen (N2). The principle sources of NOx are industrial-sized
boilers such as electric power plants and the internal combustion engines in cars, trucks,
locomotives, airplanes, and the like.
Reduced nitrogen, or ammonia, is responsible for approximately one-third of the total nitrogen
atmospheric emissions that eventually end up as loads to the Bay. Ammonia sources are
predominately agricultural, and ammonia is released into the air by volatilization of ammonia
from manures and emissions from ammonia based fertilizers. Minor sources include mobile
sources, slip ammonia released as a by-product of emission controls on NOx at power plants, and
industrial processes.
Two types of atmospheric deposition—wet and dry—are input to the Bay Watershed and Bay
Water Quality Models daily. Wet deposition occurs during precipitation events and contributes
to nitrogen loads only during days of rain or snow. Dry deposition occurs continuously and is
input at a constant rate daily in Bay Watershed and Bay Water Quality Models.
Because the Bay Watershed and Bay Water Quality Models are mass balance models, all sources
of nitrogen and phosphorus inputs to the tidal Bay must be accounted for. Given atmospheric
deposition of phosphorus and organic forms of nutrients are minor inputs, the Bay Watershed
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Chesapeake Bay TMDL
and Bay Water Quality Models account for estimated loads of phosphorus and organic nutrients
to open surface waters only, on the assumption that all phosphorus and organic nutrients are
derived from aeolian or wind processes, which result in no net change in organic nitrogen on
terrestrial or land surfaces but result in a net gain when deposited directly on water surfaces.
Organic nitrogen is simulated only as wet deposition as dissolved organic nitrogen because the
magnitude of dry deposition of organic nitrogen is not well characterized in the literature.
Therefore, the limited dry deposition of organic nitrogen simulated by the Bay Airshed Model is
lumped into the oxidized nitrogen atmospheric dry deposition.
Atmospheric deposition monitoring in the Chesapeake watershed is through National
Atmospheric Deposition Program (NADP) and AirMon stations throughout the watershed.
Measured deposition at these discrete stations is used to extrapolate to all the land and waters of
the Chesapeake watershed through a wet deposition regression model developed by Grimm and
Lynch (2000, 2005; Lynch and Grimm 2003). Dry deposition data are estimated through the
Community Multiscale Air Quality Model (CMAQ) (Dennis et al. 2007; Hameedi et al. 2007)
(for more details, see Section 5.4).
Chesapeake Bay Airshed
The Bay's NOx airshed—the area where emission sources that contribute the most airborne
nitrates to the Bay originate—is about 570,000 square miles, or nine times the size of the Bay's
watershed (Figure 4-16). Close to 50 percent of the nitrate deposition to the Bay is from air
emission sources in Bay watershed jurisdictions. Another 25 percent of the atmospheric
deposition load to the Chesapeake watershed is from the remaining area in the airshed. The
remaining 25 percent of deposition is from the area outside the Bay airshed. The ammonia
airshed is similar to the NOx airshed, but slightly smaller.
REDUCED
CWODtZEO
Source: Dr. Robin Dennis, EPA/ORD/NERL/AMAD/AEIB
Figure 4-16. Principle area of NOX emissions (outlined in blue) that contribute nitrogen deposition to the
Chesapeake Bay and its watershed (solid blue fill) (the Bay airshed).
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Chesapeake Bay TMDL
Atmospheric Deposition Emissions Sources and Trends
Between 1985 and 2005, the simulation period of the Bay Watershed Model, atmospheric
deposition loads of nitrate (NOx) in the Chesapeake watershed have decreased by about 30
percent (Figure 4-17). Considerable variability exists across the watershed, however, with the
greatest reductions occurring in the northern and western portions (Grimm and Lynch 2000,
2005; Lynch and Grimm 2003). Figure 4-17 shows the trend of estimated average nitrate and
ammonia deposition concentrations in the Phase 5 Model from 1984 to 2005. The average annual
concentration from 1984 to 2005 was used as an adjustment to smooth out the high- and low-
rainfall years, which bring different amounts of deposition load to the watershed depending on
the volume of precipitation. Much of the reduction has been from point source air emission
reductions, particularly from electric generating units (EGUs) such as electric power plants.
Reductions from mobile sources, such as cars and trucks, are another large contributor to the
downward trend.
Annual Concentrations in Atdep
06
05
04
03
02
0.1
y«-0.0053x + 11.012
R! • 0.5791
y--0.0281x +56761
RJ-0.8372
NH3
• NO3
• DIN
NH3
• NO3
• DIN
Linear (NH3)
^— Linear (DIN)
Linear (N03)
— Linear (DIN)
Linear (N03)
Linear (NH3)
0
1980
1995
Year
2000
2005
2010
Source: Phase 5.3 Chesapeake Bay Watershed Model.
Figure 4-17. Trend of estimated average nitrate and ammonia deposition concentrations in the Phase 5 Model
domain from 1984 to 2005.
Table 4-17 shows the estimated portion of deposited NOx loads on the Chesapeake watershed
from four sectors including EGUs, mobile sources, industry, and all other sources. From 1990 to
2020, considerable reductions have been made in the power sector. In addition, both on road and
off-road mobile sources have ongoing fleet turnover and replacement, which is putting cleaner
spark and diesel engines in service, and that is expected to continue beyond 2030. Table 4-17
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December 29, 2010
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Chesapeake Bay TMDL
shows that in 1990, EGUs are the dominant source of NOx; in 2020, mobile sources will be the
dominant sources of NOx with EGUs the least contributor of NOx. However Figure 4-17 shows
that all sources will be decreasing their NOx emissions, and the total deposition load in 2020 will
be less than the 1990 load.
Average ammonia loads over the Phase 5 Chesapeake Bay Watershed Model domain have
followed the trend in overall manure loads in the watershed and have remained steady over the
1985 to 2000 simulation period (Figure 4-17). Ammonia deposition is very site-specific and
strongly influenced by local emissions. Local and regional trends in manure, such as the rise of
poultry animal units in the Eastern Shore and Shenandoah basins and reduction of dairy farms in
the northern portions of the watershed in the late 1980s, affect regional ammonia deposition in
the Chesapeake watershed.
Table 4-17. Estimated portion of deposited NOx loads on the Chesapeake
watershed from four source sectors—EGUs, mobile sources, industry,
and all other sources in 1990 and 2020
Source sector
Power plants (EGUs)
Mobile sources (on-road)
Industry
Other (off-road-construction; residential, commercial)
1990
40%
30%
8%
21%
2020
17%
32%
20%
31%
Source: Dr Robin Dennis, EPA/ORD/NERL/AMAD/AEIB
4.6.3 Forest Lands
Forested areas represent a significant portion of the Chesapeake Bay watershed (see Figure 2-3),
as approximately 70 percent of the watershed is composed of forested and open wooded areas.
This land use contributes the lowest loading rate per acre of all the land uses, however.
Compared with other major pollutant source sectors in 2009. forest lands in the Bay watershed
contributed an estimated 20 percent (49 million pounds per year) of total nitrogen, 15 percent
(2.4 million pounds per year) of total phosphorus, and 18 percent (730,000 tons per year) of
sediment of the total delivered loads to the Bay from the watershed (Bay Watershed Model 2009
Scenario).
Forest land differs from most land uses in that a significant portion of the loads that come off the
land do not originate in the forests. Most of the nitrogen loads come from atmospheric deposition
of nitrogen (Campbell 1982; Langland et al. 1995; Ritterand Chirnside 1984; Stevenson et al.
1987: Nixon 1997; Castro et al. 1997; Goodale et al. 2002; Pan et al. 2005; Aber et al. 1989;
2003; Stoddard 1994). Sediment and phosphorus loads originate from poorly managed forest
harvesting with unprotected stream crossings and unhealthy forest biota (Riekerk et al. 1988;
Clark et al. 2000).
The Bay Watershed Model differentiates between harvested and un-harvested forest lands as
distinct land uses. Un-harvested forest lands contributed 1.63 Ibs of nitrogen, 0.08 Ib of
phosphorus, and 0.02 ton of sediment per acre, which is the lowest loading rate of any land use.
In contrast, harvested forest contributes 10.30 Ibs of nitrogen, 0.47 Ib of phosphorus, and 0.19
ton of sediment per acre. The loads from harvested forest can be greatly reduced by using forest
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Chesapeake Bay TMDL
harvesting BMPs. The loads are estimated through model calibration, which estimates loading
rate per area on the basis of monitoring stations in forested areas.
For additional information related to the representation of forest lands, see the Bay Watershed
Model documentation at http://ww\v.chesapeakebav.net/model phase5.aspx?menuitem=26169.
4.6.4 On-site Waste water Treatment Systems
Onsite Wastevvater Treatment Systems (OSWTS), commonly referred to as septic systems, have
the potential to deliver nitrogen and phosphorus to surface waters directly because of system
failure and malfunction and indirectly through groundwater. Septic systems treat human waste
using a collection system that discharges liquid waste into the soil through a series of distribution
lines that compose the drain field. In properly functioning (normal) systems, phosphates are
adsorbed, or gathered onto the soil surface, and retained by the soil as the effluent percolates
through the soil to the shallow, groundwater table. Therefore, functioning systems do not
contribute nitrogen and phosphorus loads to surface waters directly. A septic system failure
occurs when there is a discharge of waste to the soil surface where it is available for washoff. As
a result, failing septic systems can contribute high nitrogen and phosphorus loads to surface
waters. Short-circuited systems (those close to streams) and direct discharges to streams also
contribute significant nitrogen and phosphorus loads.
OSWTSs represented an estimated 6 percent of the total nitrogen load from the Chesapeake
watershed in 2009 (Bay Watershed Model 2009 Scenario). Information on the watershed loads
from OSWTSs is generally sparse. Detailed descriptions of data procedures, source information,
and assumptions used in estimating those loads are in Palace et al. (1998).
For the Chesapeake Bay Watershed Model, the number of OSWTSs in each modeling segment
was estimated by calculating the number of households outside areas served by public sewer.
One septic system was assumed to exist for each household. Digital maps of 2009 sewer service
areas were provided by 257 of the 403 major wastewater treatment plants in the watershed
contacted during a 2009 survey sponsored by EPA. Digital data were also provided by the
Maryland Department of Planning for all of Maryland, Fairfax County, and the Washington
Council of Governments. In 2008 the CBP Office contacted some local jurisdictions and
collected sewer service area data for all three Delaware counties, Albemarle. Arlington, Henrico,
Loudoun, and Rockingham counties in Virginia and for James City, Newport News City,
Virginia Beach, and Richmond in Virginia. Data were also collected for Perry, Dauphin,
Lancaster, Lycoming, and Cumberland counties in Pennsylvania, and for Broome County in
New York. For those major wastewater treatment plants that did not provide data and were not
included in data supplied by county or state agencies, the extent of their sewer service area was
estimated on the basis of population density.
EPA simulated the extent of existing sewer service areas using a thresholded and log-
transformed raster data set of year 2000 population density. A population density raster was
created using a dasymetric mapping technique with 2000 Census Block Group data and a
secondary road density raster map (Claggett and Bisland 2004). A logarithmic transformation
was used to normalize the population density data in the surface raster. The standard deviations
in the data range were examined to find the optimal threshold for representing sewer service
4-37 December 29, 2010
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Chesapeake Bay TMDL
areas in Maryland because statewide maps of existing sewer service areas were provided by the
Maryland Department of Planning. A threshold of 1.5 standard deviations from the mean (> -
0.4177) was chosen and used to reclassify the surface raster into a binary grid. A low-pass filter
(ignoring no data) was then used to smooth the data, and the output was converted from a
floating point to an integer grid. The resulting integer grid was used to represent potential sewer
service areas for wastewater treatment plants that did not submit digital data. Households in the
Bay watershed were mapped using a similar dasymetric mapping technique and 2000 Census
household data. The resulting raster data set of households was overlaid on the sewer service
area map to estimate the number of households outside sewer service areas. The data were scaled
from the year 2000 to the year 2009 using published annual county-level population estimates
adjusted for changes in average household size. In addition, the data were scaled back through
time using county-level population estimates and spatially distributed raster data sets
representing 1990 and 2000 Census Block Group data on the total number of households.
Using that methodology, the number of OSWTSs is estimated and the nitrate loads exported to
the river from OSWTSs are simulated. Phosphorus loads are assumed to be entirely attenuated
by the OSWTSs. Standard engineering assumptions of per capita nitrogen waste and standard
attenuation of nitrogen in the septic systems are applied. Overall, the assumption of a load of 4.0
kg/person-year is used at the edge of the OSWTS field, all in the form of nitrate.
Using an average water flow of 75 gallons/person-day for a septic tank (Salvato 1982), a mean
value of 3,940 grams of nitrogen/person-year for groundwater septic flow, 4,240 grams/person-
year for surface flow of septic effluent, and typical surface/subsurface splits as reported by
Maizel et al. (1995), a total nitrogen concentration of about 39 mg/L at the edge of the septic
field was calculated. This concentration compares favorably with Salvato (1982) who calculated
OSWTS total nitrogen concentrations of 36 mg/L. It is assumed that attenuation of the nitrate
loads between the septic system field and the edge-of-river nitrate loads represented in the Bay
Watershed Model is due to: (1) attenuation in anaerobic saturated soils with sufficient organic
carbon (Robertson et al. 1991; Robertson and Cherry 1992); (2) attenuation by plant uptake
(Brown and Thomas 1978); or (3) attenuation in low-order streams before the simulated river
reach. Overall, the total attenuation is assumed to be 60 percent (Palace et al. 1998) that is
applied to all OSWTS in the Bay watershed except for MD where the zone specific attenuation
rates developed by MDE were used. MDE assumes an 80 percent delivery rate (or 20 percent
attenuation) in critical areas; a 50 percent delivery rate within 1,000 feet from any perennial
surface water; and a 30 percent delivery rate from distances greater than 1,000 feet from any
perennial surface water
(http://www.mde.state.ind.us/assets/document/NutrientCap_Tradint: Policv.pdf).
Additional information related to how the number of OSWTSs is estimated and how they are
represented in the model is available in the Bay Watershed Model documentation at
http://www.chesapeakebav.net/model phase5.aspx?mcnuitem=26169
4.6.5 Nonregulated Stormwater Runoff
The sources of nitrogen, phosphorus and sediment from nonregulated stormwater are generally
the same as those from regulated stormwater. Sources include residential and commercial
application of fertilizer, land disturbance and poorly vegetated surfaces, atmospheric deposition
4-38 December 29, 2010
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Chesapeake Bay TMDL
of nutrients, pet wastes, and developed properties. Together with regulated stormwater, the
nitrogen, phosphorus, and sediment loads affect local water quality and habitats and represent a
significant proportion of nitrogen, phosphorus, and sediment loads to the Bay. The CBP
estimates that, in 2009, urban and suburban development and runoff contributed to 16 percent of
the sediment loadings, 15 percent of the phosphorus loadings, and 8 percent of the nitrogen
loadings to the Bay (Bay Watershed Model 2009 Scenario).
The regulated sources of stormwater are discussed in the point sources section above (4.5.5). For
the purposes of the TMDL, urban and suburban runoff occurring outside the NPDES regulatory
purview is considered nonpoint source loading and is a component of the LA. However, note that
CWA section 402(p) provides the authority to regulate many of those discharges. If any of the
discharges are designated for regulation, they would then be considered part of the WLA. As
discussed in Section 8 some of the unregulated sources of stormwater are being shifted from the
LA portion to the WLA portion of the TMDL as potential regulated sources to further increase
the reasonable assurance that the TMDL reductions will be achieved. Some jurisdictions might
have state stormwater regulatory programs and, therefore, could have little to no nonregulated
stormwater sources.
For additional details related to how the non-regulated stormwater runoff loads were estimated in
the Bay Watershed Model, see Section 7 in the Bay Watershed Model documentation at
http://www.chesapeakebay.net/model phase5.aspx?menuitem=26169.
4.6.6 Oceanic Inputs
The Chesapeake Bay is an estuary and, by definition, a mixture of fresh and salt water. The
relative proportion of ocean water in any region of the Bay can be roughly estimated by its
salinity because salt is a perfectly conservative tracer. The salinity of full strength seawater just
outside the Chesapeake Bay mouth is about 35 parts per thousand (ppt). At mid-Bay around the
where Potomac River enters the mainstem Bay, the salinity drops to about 15 ppt, or a mixture of
about half seawater (43 percent) and at the Bay Bridge between Annapolis and Kent Island,
Maryland, salinity drops to about 6 ppt or 20 percent seawater. While nitrogen, phosphorus and
sediment concentrations are relatively low in ocean water, the large volume of seawater entering
the Bay brings considerable nitrogen, phosphorus, and sediment loads to the Bay.
Ocean input loads of nitrogen, phosphorus, and sediment to the Chesapeake Bay are determined
by calibration to the three Bay water quality monitoring stations at the mouth of the Chesapeake
Bay by using the Curvilinear-grid Hydrodynamic Three-Dimensional model (CH3D
Hydrodynamic Model), which has a model grid and domain that extends about 10 km beyond the
mouth of the Bay. Ocean boundary concentrations are set monthly in the Chesapeake Bay Water
Quality and Sediment Transport Model (Bay Water Quality Model) to best represent the
nitrogen, phosphorus, and total suspended solids concentrations of the monitoring stations at the
Chesapeake Bay month on an incoming tide.
A previous study of ocean boundary loads found that when accounting for all input loads to the
Chesapeake Bay, including atmospheric deposition to tidal waters and ocean inputs, the ocean
inputs were significant and accounted for about one-third of the total nitrogen and about half the
total phosphorus loads to the Bay (Thomann et al. 1994). Ocean sediment inputs are
4-39 December 29, 2010
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Chesapeake Bay TMDL
predominantly sand and have little influence on light attenuation beyond the Bay mouth and
lower mainstem Bay.
Several nutrient budgets of the ocean waters off the Chesapeake, also called the Middle Atlantic
Bight have been made (Fennel et al. 2006; Howarth et al. 1995; Howarth 1998). Howarth (1998)
estimates that for the northeast coast of the United States, which includes the discharge of all
watersheds from Maine to Virginia draining to the Atlantic, the watershed inputs of nitrogen to
coastal waters are 0.27 teragram (10 grams) from rivers and estuaries. Estimated inputs from
direct atmospheric deposition to coastal waters are 0.21 teragram, and inputs from deep ocean
upwelling are 1.54 teragrams for a total input to the coastal ocean of 2.02 teragrams.
The direct atmospheric deposition loads are roughly equivalent to the watershed loads in the
northeast United States. The estimated distribution of 2001 atmospheric deposition loads to
North America and adjacent coastal ocean is shown in Figure 4-18. Using the Community Multi-
scale Air Quality (CMAQ) Model estimates of atmospheric deposition loads to the coastal ocean
under different air scenarios provides a means of adjusting the ocean boundary loads to changes
in atmospheric deposition. Appendix L describes how the ocean boundary loads were adjusted to
reflect projected changes in nitrogen atmospheric deposition to the coastal ocean and, therefore,
coastal ocean nitrogen loads delivered to Chesapeake Bay.
24J0799
21.0
18.0
15.0
12X1
9.0
6.0
3.0
0.0
kg/ha
Source: Dr. Robin Dennis, EPA/ORD/NERL/AMAD/AEIB
Figure 4-18. Estimated 2001 annual total deposition of nitrogen (kg/ha) to North America and adjacent coastal
ocean.
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December 29, 2010
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Chesapeake Bay TMDL
4.6.7 Streambank and Tidal Shoreline Erosion
Steambank Erosion
Streambank erosion is erosion from the reworking of streams and rivers, either as flow rates
change as in the case of increased imperviousness in a watershed (Center for Watershed
Protection 2003), because of long-term changes in the landscape (Walter and Merritts 2008;
Trimble 1999), or as a natural process of river channel dynamics (Leopold et al. 1995).
In the Chesapeake Bay watershed, the relative amounts of Streambank erosion and erosion from
the land is difficult to quantify (Gellis et al. 2009) because the water quality monitoring stations
measure the total suspended sediment in the free-flowing rivers, which is composed of sediment
from both sources. The Bay Watershed Model has estimates of land erosion derived from
RUSLE estimates made in the National Resource Inventory
(http:/Avww.nrcs.usda.gov/technical/NRI/). which could be used to quantify that source of
sediment relative to the scour and erosion simulated in the rivers, but both sources of information
are thought to be too crude to estimate the splits in erosion loads on a segment basis. However,
on a watershed-wide basis, both sources of information estimate that 70 percent of the sediment
delivered to the Bay comes from erosion from land and 30 percent comes from bank erosion.
That is consistent with other estimates from research and field studies that find a wide variance
of the portions of delivered erosion from land surfaces and bank erosion but could be generalized
to about one-third of the erosion as coming from bank erosion (Figure 4-19).
Sources of Erosion
Pocomoke River • Mattawoman Creek L. Conestoga Creek
Construction
Forest
10 20 30 40
70 80 90 10
Source: Gellis et al 2009
Figure 4-19. Relative estimates of sources of erosion from land sources (crop, forest, or construction) or
bank sources banks and ditch beds).
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December 29, 2010
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Chesapeake Bay TMDL
Because sediment monitoring stations in the watershed collect all the sediment loads passing the
station, including both land erosion and bank erosion sources, the stream bank load is accounted
for, ultimately, both in the Chesapeake Bay watershed monitoring network and in the Bay
Watershed Model, at least as part of the totalcombination of sediment from land and riverine
sources. In the same way, streambank loads are also accounted for in tracking sediment load
reductions from stream restoration actions and through reductions of nitrogen, phosphorus, and
sediment tracked in the jurisdictions' WIPs.
Tidal Shoreline Erosion
Tidal shoreline erosion is a combination of the erosion of fastland (or shoreline) and nearshore
erosion. Figure 4-20 illustrates the tidal shoreline erosion process. Fastland and nearshore is
subtidal and usually unseen. Subtidal erosion can be accelerated when shoreline protection
activities such as stone revetment, a facing of stone placed on a bank or bluff to protect a slope,
are used. That practice typically cuts off fastland erosion, but the reflected wave energy
continues subtidal erosion until the wave energy no longer scours the bottom to the depth of a
meter or more.
Watershed Erosion
(rivers & local sources)
Oceanic
Input
Source: CBP Sediment Workgroup
Figure 4-20. Sources of total suspended solids In the Chesapeake including the two components of shoreline
erosions, fastland and nearshore erosion.
Estimates of shoreline erosion were provided for the Bay Water Quality Model. Estimates of the
shore recession rate, the elevation of the fastland, and the subtidal erosion rate were used to
develop the shoreline erosion estimates. Figure 4-21 demonstrates considerable variation in the
sediment load delivered by sediment erosion from segment to segment.
4.6.8 Tidal Resuspension
The bottom of the Chesapeake Bay is covered by sediment that has been either carried into the
estuary by rivers draining the Bay's extensive watershed; eroded from the Bay's lengthy
shoreline; transported up-estuary from the Atlantic Ocean, through the mouth of the Bay;
introduced from the atmosphere; or generated by primary productivity (Langland and Cronin
2003). Tidal resuspension is generated by episodic wave or current energy that scours the bottom
sediment and resuspends the surficial sediment layers.
4-42 December 29, 2010
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Chesapeake Bay TMDL
4,000.000
3.500.000 •
5.000.000
I Shoreline
i Watershed
2,500.000
I
2.000.000
y
1.500.000
1,000.000
soo.ooo
llll.l.lll.ll.lll,,l hl.ll.ll
Source: Chesapeake Bay Water Quality and Sediment Transport Model.
Figure 4-21. Estimated tidal sediment inputs for 1990 from the Chesapeake Bay watershed and from shore
erosion. Shoreline sediment inputs (here labeled bank load) are estimated to be about equal to watershed
inputs (here labeled as nonpolnt source).
In the Bay Water Quality Model, a wave resuspension model simulates such episodic events. In
some regions of the Bay, resuspended sediment can be one of the most detrimental sediment
loads to SAV restoration as shown in results of sediment scoping scenarios run on the Bay Water
Quality Model (Table 4-18). The Bay Water Quality Model was run to compare the base
scenario of the 2010 Tributary Strategy against model scenarios that individually eliminated
watershed loads of total suspended sediment, fall line loads of total suspended sediment, shore
erosion loads, sediment resuspension loads, and ocean sediment loads. The model scenarios were
run to determine which sediment source was most important. In most of the mainstem Bay,
sediment resuspension loads were relatively more detrimental to SAV growth than were other
sediment sources.
4.6.9 Wildlife
Wildlife sources are rarely, if ever, considered in nitrogen and phosphorus TMDLs because
wildlife only cycle nitrogen and phosphorus that already exist in the system. To the extent that
wildlife increases the availability of nitrogen and phosphorus for runoff, wildlife nitrogen and
phosphorus loads are inherently represented in land use sources. As a specific example, the loads
4-43
December 29, 2010
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Chesapeake Bay TMDL
Table 4-18. Chesapeake Bay Water Quality and Sediment Transport Model -simulated
SAV acres under a range of sediment scoping scenarios compared with the 2010
Tributary Strategy scenario
CBSEG
CB1TF
CB2OH
CB3MH
CB4MH
CB5MH
CB6PH
CB7PH
CB8PH
SAV
acre
11,253
212
609
1,150
9,432
825
14,236
6
No
watershed
loads %
Increase
over base
23%
63%
44%
30%
9%
21%
4%
25%
SAV
acre
11,001
192
539
1,039
9,086
695
13,798
5
No fall
line loads
%
increase
over base
20%
47%
28%
18%
5%
2%
1%
17%
SAV
acre
9,751
177
478
1,096
10.341
701
13,959
5
No shore
erosion
loads %
increase
over
base
6%
36%
13%
24%
20%
3%
2%
5%
SAV
acre
10,344
269
704
1.671
14,055
980
14,582
6
No resus-
pension
loads %
increase
over base
13%
107%
67%
89%
63%
44%
7%
29%
SAV
acres
9,173
138
450
980
9,177
728
14,162
5
No ocean
sed loads
%
increase
over
base
0%
6%
7%
11%
6%
7%
4%
18%
a. The percentages are the percentage increase in simulated SAV acres over the 2010 Tributary Strategy scenario SAV acres
from the wooded land incorporate nitrogen and phosphorus loads that are cycled through
wildlife. The overall loads from the watershed and each land use type are calibrated to observed
data and literature load estimates, which also include loads cycled through wildlife. As a result,
no explicit allocation to wildlife is necessary or appropriate in the Bay TMDL.
4.6.10 Natural Background
The Bay Airshed Model, Watershed Model, and Bay Water Quality Model all include the loads
from natural background conditions because all the Bay models are mass balance models and are
calibrated to observed conditions. For example, the atmospheric deposition loads are monitored
principally at the NADP sites. The deposition measured at those sites includes NOx from natural
sources, which includes lightning, forest fires, and bacterial processes such as nitrification, which
oxidizes ammonia (NHs) to NC^ or NO?. Those sources compose about I percent of the NOx
deposition in the Chesapeake region (USEPA 20lOi). Natural background sources of ammonia
are easily volatilized from land and water surfaces and are generated from the decay
(ammonification) of natural sources of organic nitrogen. Those are likewise a relatively small
portion, relative to anthropogenic sources, of the atmospheric loads estimated by the NADP sites.
Natural loads of nitrogen, phosphorus, and sediment from forested land are also part of the
monitored load at the free-flowing stream, river, and river input monitoring stations throughout
the Chesapeake Bay watershed. Because the loads are part of the total loads to which the
Chesapeake Bay Program's mass balance models are calibrated, the natural nitrogen,
phosphorus, and sediment loads in the system, while small, are fully accounted for in the Bay
TMDL assessment.
The natural background loads can best be estimated by simulating the All Forest scenario, which
includes no point source, manure, or fertilizer loads. Atmospheric deposition loads in that
scenario are set at estimated pristine levels. The scenario yields delivered nitrogen, phosphorus,
and sediment loads that are more than an order of magnitude less than current conditions (see
Appendix J).
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December 29, 2010
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Chesapeake BayTMDL
SECTION 5. CHESAPEAKE BAY MONITORING AND
MODELING FRAMEWORKS
For purposes of developing the Chesapeake Bay TMDL, data and scenario results from extensive
monitoring networks and a series of linked environmental models simulating the nitrogen,
phosphorus, and sediment pollutant load sources and the associated water quality and biological
responses have been applied to support decision making by EPA and its partner Bay watershed
jurisdictions. The suite of models were developed, calibrated, and verified using long-term Bay,
watershed, airshed, and land-cover monitoring network observations and published technical and
scientific findings.
The suite of Bay and watershed monitoring networks and the Bay modeling framework provide
the most accurate and reliable representations of the complex Bay water quality processes
currently available. Quality assured monitoring data collected over multiple decades from
hundreds of stations provides the most direct measures of Bay and watershed water quality
conditions and biological responses. The linked Bay models are valuable tools in synthesizing an
enormous amount of data and scientific findings, projecting possible outcomes to a range of
management actions, and assessing pollutant load reductions needed to restore Bay water quality.
Although models have some inherent uncertainty, the amount of data and resources taken to
develop, calibrate, and verify the accuracy of each of the Bay models, minimized the uncertainly
of the suite of Bay models.
5.1 TECHNICAL MONITORING AND MODELING REQUIREMENTS
The combined Chesapeake Bay monitoring networks and modeling frameworks effectively
address all the factors necessary for developing a scientifically sound and reliable TMDL that
meets the TMDL regulatory requirements. The factors addressed in and through the various
monitoring networks and linked models include the following:
• Regulated point sources and non-regulated nonpoint sources of nitrogen, phosphorus, and
sediment are fully considered and evaluated separately in terms of their relative
contributions to water quality impairment of the Chesapeake Bay's tidal waters.
• Water quality impairments in the Chesapeake Bay and its tidal tributaries and embayments
are temporally and spatially variable and are directly linked to nitrogen, phosphorus, and
sediment pollutant loadings.
• Time-variable aspects of land-based best management practices that have a large effect on
nitrogen, phosphorus, and sediment loadings and resulting water quality in the Bay are
fully simulated.
• All sources of data are gathered using documented methodologies fully consistent across
the Bay watershed and the Bay's tidal shorelines and waters helping to ensure equitable
allocation of the resultant load reduction responsibility across the seven watershed
jurisdictions and multiple pollutant source sectors.
• The Bay modeling framework takes advantage of decades of atmospheric deposition,
streamtlow. precipitation, water quality, biological resource, and land cover monitoring
5-1 December 29, 2010
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Chesapeake Bay TMDL
data generated through the Bay-wide tidal and basinwide watershed monitoring networks
as well as tracking and reporting of the implementation of pollution load reduction best
management practices, conservation practices, and technologies for model calibration and
verification.
• A wide variety of hydrological conditions, across the decadal-scale model hydrologic
periods, have been characterized through decades of Bay watershed and tidal water
monitoring to provide reliable simulations in support of management decisions.
• The combined monitoring networks and linked Bay models provide the ability to simulate
and assess the critical spatial and temporal variability of the Bay water quality criteria
parameters—dissolved oxygen, water clarity, underwater Bay grass acreage, and
chlorophyll a—as adopted into the four Bay jurisdictions' WQS regulations.
The primary regulatory factor that must be addressed by the combined monitoring networks and
linked models is whether the Bay TMDL allocation scenario will attain and maintain the
applicable jurisdictions' WQS. To make that assessment, the Bay models must be able to relate
the nitrogen, phosphorus, and sediment pollutant loadings from all sources and across all tidal
waters to achievement of the four Bay jurisdictions' Chesapeake Bay WQS. A determination that
a particular scenario achieves compliance with the applicable water quality criteria within each
segment for each of the jurisdictions' WQS requires evaluating the water quality impacts of
pollutant loadings on multiple parameters across all seasons over a minimum of 3 years within a
10-year hydrologic period (USEPA 2003a, 2007a). As a result, the full suite of Bay models must
provide a time-variable analysis. In addition, to support a determination of reasonable assurance,
the Bay modeling framework must also be useful in developing and evaluating action plans for
implementation, and confirming those combined implementation actions will yield achievement
of Chesapeake Bay WQS (USEPA 2008b, 2009c, 2009d).
5.2 BAY MONITORING FRAMEWORK OVERVIEW
In August 1984, the Chesapeake Bay tidal monitoring program was created to achieve three
objectives: characterize the baseline water quality conditions; detect trends in water quality
indicators; and increase the understanding of ecosystem process and factors affecting Bay water
quality and living resources (MD OEP 1987). The long-term Chesapeake Bay and watershed
monitoring networks have accomplished many more objectives in the past 26 years, including
the following:
• Classifying status and tracking trends in tidal Bay and Bay watershed water quality and
living resources response to management actions and other anthropogenic and natural
factors
• Supporting a scientific basis for targeting a dual nitrogen/phosphorus load reduction
strategy for Bay water quality and habitat health recovery
• Identifying eutrophication as the primary cause of the SAV decline
• Providing sufficient and diverse data supporting scientifically based and peer-reviewed
estuarine water quality criteria development to guide restoration targeting and water quality
assessments (e.g., CWA section 303(d) listing/delisting decisions)
5-2 December 29, 2010
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Chesapeake Bay TMDL
• Supporting geographic and pollutant source specific targeted implementation for the most
cost effective, reduction efficient management actions
• Supporting decision makers' needs for the Bay TMDL process with high-quality data
underlying the Chesapeake Bay watershed and tidal water quality, sediment transport,
biological resource, and filter feeder models' development, calibration, verification and
management application
5.2.1 Partnership's Chesapeake Bay Tidal Monitoring Network
Undergoing adaptive changes over the almost three decades as the partnership's management
needs and requests have significantly evolved over time (CBP I989a, I989b; USEPA 2003a;
MRAT 2009), the Chesapeake Bay tidal monitoring network includes the following:
• Tidal water quality monitoring for 26 parameters at over 150 stations distributed over the
92 Chesapeake Bay tidal segments across Delaware, the District of Columbia, Maryland.
and Virginia
• Shallow-water monitoring addressing a select set of segments on a rotational basis
• Benthic infaunal community monitoring at fixed and random stations across the tidal
waters
• Annual aerial and ground surveys of underwater Bay grasses
• Decadal records of phytoplankton and zooplankton monitoring
• Fisheries independent population monitoring programs and surveys
Each component of the tidal monitoring network has been designed to support the four Bay
jurisdictions' tidal water Bay section 303(d) listing decision makings, addressing DO, water
clarity, SAV, and chlorophyll a criteria attainment assessments and benthic infaunal community-
based impairment decisions (USEPA 2003a, 2004a, 2007a, 2007b, 2008a, 20lOa).
The Bay tidal monitoring network is funded, operated, and maintained through a longstanding
state-federal-university partnership that produced the fundamental monitoring data supporting
Bay TMDL development. This data is also utilized in public reporting on the health of the Bay,
its tidal rivers, and supporting ecosystem; assessment of achieving the Bay jurisdictions'
Chesapeake Bay WQS regulations; evaluation of the effectiveness of actions to reduce nitrogen,
phosphorus, and sediment pollution loadings from the surrounding watershed; developing,
calibrating, verifying and applying models; and generating and reporting water quality and living
resource indicators.
Chesapeake Bay Water Quality Monitoring
The long-term Chesapeake Bay water quality monitoring program uses a fixed station strategy
with sites distributed along the mid-channel waters of the Bay, its tidal tributaries and
embayments. The exact number of stations has varied over the 26-year history of the program. A
set of 162 stations that have been sampled consistently for the majority of those years is
illustrated in Figure 5-1. One or more stations are in each of the 92 Bay segments. Over the
26-year history of the program, sampling frequency has ranged from 20 times per year to the
5-3 December 29, 2010
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Chesapeake Bay TMDL
present 14 cruises annually. Synoptic sampling of all the tidal waters takes 1-2 weeks with the
available funding, field staff, and sampling vessel resources.
• Tidal Network Monitoring Station
Monitoring Segment
Baltimore
/'u/.;/i»Tf>/?mv
asFfes*-
\c
/ Jk^l1 ^ < "AfJ/tT MtXT
't 'iHtfViU"
«•'•«"•"
Richmond
.'tfmft/fj
^ A • ;
^2
N
«Xj>'
f
Norfolk
o » to xm
Figure 5-1. Tidal Chesapeake Bay water quality monitoring network stations.
5-4
December 29, 2010
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Chesapeake Bay TMDL
The tidal water quality monitoring program is designed to represent the complexities of the
estuary. Every 2-4 weeks, a three-dimensional view is obtained by sampling various depths from
the surface to the bottom of the water column at each station, with each of the 92 Bay segments
having one or more sampling sites. Sites are sampled at least once each month. Standardized
sampling and analytical methods are used to detect low levels of nutrients, chlorophyll ti and
particulates; these methods were approved by EPA in 1986 and are still used today (USEPA
1996).
At each station, vertical profiles of in-situ water quality measurements are made using
instrumentation and standard operating procedures approved by the Chesapeake Bay Program's
Analytical Methods and Quality Assurance Workgroup (see Section 5.2.3). Measurements are
collected at 0.5 m, 1.0 m, 2.0 m, and 3.0 m, and at a maximum of 2-meter intervals from 1.0 m
below the surface to 1.0 m above the bottom. Water temperature, DO. conductivity, and pH are
recorded at each depth. Photosynthetic Active Radiation (PAR) measurements are made, and
Secchi depth measurements are recorded using a Secchi disc.
At stations where stratification provides a pycnocline. as determined by the partnership's
approached protocol (USEPA 2004a) discrete samples are collected at 0.5 m below the surface.
at 1.5 m above the upper pycnocline, at 1.5 m below the lower pycnocline and at 1.0 m above the
bottom. At stations with no identifiable pycnocline as determined by the protocol, discrete
samples are collected at 0.5 m below the surface and 1.0 m above the bottom, and at the physical
profiling depths which are above one-third and two-thirds the distance between the surface- and
bottom-sampling depths. Each of the discrete sample depths corresponds to an in-situ water
quality measured profiling depth.
Chesapeake Bay Shallow-Water Monitoring
For shallow-water tidal habitats, monitoring consists of high-speed, spatially detailed water
quality mapping (data collected every 4 seconds) called DATAFLOW, and high-frequency
(15-minute measurement intervals) continuous monitoring at fixed sites (CONMON) (USEPA
2007a; MD DNR 2009; VIMS 2009). Both DATAFLOW and CONMON record high-resolution
measurements of water temperature, DO concentration, DO saturation, pH, salinity (derived
from conductivity), turbidity (used to estimate total suspended solids or TSS), and fluorescence
(used to estimate chlorophyll a).
CONMON measurements are collected March to November. All sondes (i.e. data measurement
devices) are either at constant depth of approximately 1 m below the surface or at a fixed depth
from the bottom (0.3 m-0.5 m) depending on depth conditions. In addition to the suite of
measurements collected by the CONMON meter, LI-COR sensors measure the light penetration
at the site on each visit. A Secchi depth measurement is also collected. As a part of standardized
operating procedures to ensure data quality, each CONMON site is serviced biweekly unless
water quality readings demonstrate that weekly intervals should be maintained. During each site
visit, instruments in the water are calibrated against replacement instruments and a third
instrument. Discrete water samples are collected for chlorophyll a, turbidity, and TSS
calibration. Analyses for a suite of nutrient parameters are also conducted on the discrete water
sample. Upon swapping out instruments, the instrument removed from the field is returned to the
lab for cleaning and lab calibration before being redeployed.
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Chesapeake Bay TMDL
DATAFLOW is conducted on a subset of the 92 Bay segments each year with monthly
measurements from April to October. Measurements are made while traveling in a boat at speeds
up to 25 knots. The DATAFLOW system is compact, can tit on a small boat, and allows
sampling in shallow water every 45 seconds with the ability to map an entire small tidal tributary
or embayment in a day or less. This program complements the long-term fixed-station
monitoring by providing data in nearshore, shallow-water habitats critical to SA V where water
quality behaves differently from those measured in the mid-channel.
DATAFLOW calibration data are collected at multiple sites to either coordinate with long-term
or CONMON monitoring stations, and large signal areas to insure coverage of the data gradient
with the calibration. Discrete grab water samples are collected for chlorophyll. In addition,
measurements of physical parameters (water temperature, DO, conductivity, pH) and Secchi
depth are made, and on PAR to calculate water column light attenuation (Kd). There is extensive
quality assurance/quality control (QA/QC) on the data set upon returning from the field.
To date, 65 of the 92 Chesapeake Bay segments have I to 3 years of shallow-water monitoring
data available for assessment (Figure 5-2).
Chesapeake Bay Benthos Monitoring
The current Bay-wide benthic monitoring program, initiated in Maryland in 1984 and in Virginia
in 1985, now consists of fixed and random site components (Weisberg et al. 1997; Dauer and
Llanso 2003; Llanso et al 2003). The fixed site monitoring program has 53 stations traditionally
sampled annually in spring and summer to monitor changes over time (trends). All fixed sites in
Maryland and Virginia are sampled using three replicate bottom grabs. The probability-based,
random strata sampling was initiated in Maryland in 1994. Since 1996, the probability-based
sampling program has become the standardized approach in Virginia as well, providing for a
Bay-wide regulatory assessment estimating impaired habitat conditions. The impairment
assessment relies on approximately 200 sites sampled between July 15 and September 30 each
year (Figure 5-3).
Chesapeake Bay Submerged Aquatic Vegetation Aerial and Ground Surveys
Consistent annual SAV aerial surveys commenced in 1984 and have been completed every year
(except 1988) to the present providing detailed mapping of SAV bed coverage, acreage,
estimated density, and, in combination with ground survey, species identification (Orth et al.
2010a; VIMS 2009) (Figure 5-4). In 2001 the program increased efficiency and accuracy by
scanning aerial photography from digital negatives and orthorectifying (i.e., geometrically
correcting) the images using image processing software. SAV beds are categori/ed visually
according to density on the basis of percent cover estimates. SAV beds are generally
photographed May through October—lower Bay SAV in May and June, and low salinity and
freshwater areas August through October (Figure 5-5) (Orth et al. 20IOa; VIMS 2010).
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Chesapeake Bay TMDL
Years of Shallow Water Monitoring Data
D>
Figure 5-2. Shallow-water monitoring illustrating segment completion and latest rotation for Maryland.
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December 29, 2010
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Chesapeake Bay TMDL
Source: Dauer and Llanso 2003
Figure 5-3. 2003-2008 Chesapeake Bay stratified random benthic sampling sites used to estimate habitat
impairment through benthic community condition assessment.
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December 29, 2010
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Chesapeake Bay TMDL
Source: http://www vims.edu/bio/sav
Figure 5-4. Flightlines for the annual Chesapeake Bay SAV Aerial Survey.
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Chesapeake Bay TMDL
"' &
SASOH
Hectares if SAV: 1.222.9.3
Date Flown. 09/19, 09/21,11/07
2004 SAV Efensty Class
0-10% 10-«% 45-70% 70-100%
1,000
1,000 2,000 M.tto
S»«rr«: VIMS.USGS
Source: http://www.vims.edu/bio/sav
Figure 5-5. Illustration of mapped SAV beds, individual bed coding, bed density estimates, and species
Identification (from ground surveys).
Chesapeake Bay Phytoplankton Monitoring Program
The Chesapeake Bay Monitoring Network has included a Phytoplankton Monitoring Program
since its start in 1984. Phytoplankton samples for species enumeration, and water samples for
laboratory measurements of phytoplankton primary production are collected at fixed monitoring
stations in the mainstem and tidal tributaries of the bay (Marshall et al. 2006; Lacouture 2006).
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Chesapeake BayTMDL
Monitoring has been performed concurrently with water quality monitoring at as many as
32 stations, however, 27 stations are currently active. Staff from Old Dominion University
performed monitoring for the Virginia Department of Fnvironmental Quality and by staff from
Morgan State University Estuarine Research Center (formerly the Academy of Natural Sciences
Benedict Estuarine Research Center) for the Maryland Department of the Environment/Maryland
Department of Natural Resources. Monitoring data are available at
http://vvww.chesapeakebav.net/. Virginia data after 1999 is also available at
http://www.chcsapeakebay.odu.edu/.
Chesapeake Bay Zooplankton Monitoring Program
The Chesapeake Bay Monitoring Network included a Zooplankton Monitoring Program from
1984-2002 (Buchanan 1993; Carpenter et al. 2006). Mesozooplankton and microzooplankton
samples for species enumeration were collected at up to 36 fixed monitoring stations in the main
stem and tidal tributaries of the bay. Microzooplankton sampling was conducted in Virginia only
from 1993-2002 and gelatinous Zooplankton occurred only in Maryland. Monitoring usually
occurred concurrently with water quality monitoring. Staff from Old Dominion University
performed monitoring for the Virginia Department of Environmental Quality and by staff from
Versar, Inc and Morgan State University Estuarine Research Center (formerly the Academy of
Natural Sciences Benedict Estuarine Research Center) for the Maryland Department of the
Environment/Maryland Department of Natural Resources. Monitoring funding was briefly
reinstated to count archive samples in 2005. Monitoring data is available at
http://www.chesapeakebay.net/. Virginia data collected between 1999 and 2002 is also available
at http://www.chesapeakebay.odu.edu/.
Chesapeake Bay Fisheries Monitoring Programs
There are a series of federal, state, and Baywide fisheries monitoring programs and surveys
briefly described below.
• Commercial Landings: The NOAA National Marine Fisheries Service maintains a
database of domestic fishery landings offish and shellfish beginning with data from 1880.
with Chesapeake Bay specific commercial landings data by years, states, and species; by
years, states, species, and fishing gears. More information and online data can be found at:
http://www.st.nmfs.gov/stl/commercial/.
• The Blue Crab Winter Dredge Survey: The survey serves as the only Baywide fishery-
independent survey of the blue crab population, provides abundance and relative
exploitation estimates, as well as recruitment and female spawning potential indices
initiated in 1988 by the Maryland Department of Natural Resources and University of
Maryland Chesapeake Biological Laboratory, with the Virginia Institute of Marine Science
joining the following year. Data can be obtained from
http://www.dnr.state.md.us/fisheries/crab/vvinter dredue.html.
• Maryland Surveys: The Maryland Department of Natural Resources conducts a series of
fisheries surveys including: Potomac River Shad Survey, Maryland American Eel
Populations Surveys, Maryland Striped Bass Gill Net Seine Survey, Maryland Upper Bay
Trawl Survey, Maryland Shoal Water Trawl Survey, Calvert Cliffs Pot Survey, Maryland
Annual Oyster Spat Index and Disease Survey, and the Maryland Oyster Stock Assessment
Program. For more information see http://www.dnr.state.md.us/FlSHL:RIES/.
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Chesapeake Bay TMDL
• Virginia Surveys: The Virginia Institute of Marine Science conducts a series of fisheries
surveys including: Virginia Shad and Herring Gill Net Survey, Virginia American Eel
Young of Year Survey, Virginia Striped Bass Monitoring and Tagging Survey, Virginia
Shark Long Line Survey, Virginia Striped Bass Young of Year Beach Seine Survey,
Virginia Blue Crab Megalopae Monitoring Program, Virginia Juvenile Fish and Blue Crab
Trawl Survey, Virginia Spring and Fall Oyster Bar Survey, and the Virginia Oyster Spat
Survey. For more information see
http://www. vims.edu/research/departments/ fisheries/programs/.
5.2.2 Partnership's Watershed Monitoring Network
The Chesapeake Bay watershed monitoring network is a network of 85 streamflow gauges and
water-quality sampling sites operated across the Bay watershed (CBP 2004a; MRAT 2009)
(Figure 5-6). The network is an essential component to reporting, tracking, and modeling stream
flow as well as nitrogen, phosphorus, and sediment concentrations and loads across the
Chesapeake Bay watershed as it provides the only consistent, coordinated monitoring effort
across all seven Chesapeake Bay watershed jurisdictions. Data from the watershed monitoring
network sites have been used to develop, calibrate, and verify the Phase 5.3 Chesapeake Bay
Watershed Model (USKPA 2010J).
The CBP partnership designed the watershed streamflow and water-quality sampling network in
2004 and signed a MOU in September 2004 to implement the network (Chesapeake Bay
Watershed Partners 2004). The watershed monitoring network has undergone multiple scientific
reviews since its inception (e.g., STAC 2005a, 2005b; MRAT 2009). After a 2009 review of the
monitoring network, the original objectives of the network were modified to reflect a balance
between the long-term monitoring goals of CBP partners and the increased need for tracking
changes that could result from management actions (restoration) and other changes occurring in
the watershed. The new objectives, as adopted by the partnership through the CBP's
Management Board (MRAT 2009). are as follows:
1. Measure and assess the status and trends of nitrogen, phosphorus, and sediment
concentrations and loads in major tributaries and subwatersheds and selected
tributary strategy basins
2. Provide data suitable for the assessment of factors affecting nitrogen,
phosphorus, and sediment status and trends from major pollutant source sectors
3. Measure and assess the effects of targeted management and land-use change
4. Improve calibration and verification of the partners' watershed models
5. Support spatial and topical prioritization of pollutant reduction, restoration, and
preservation actions
As of 2010. the watershed monitoring network has 85 sites consisting of 67 sites fully
implemented (primary) and another 18 sites partially implemented (secondary) (CBP 2010a)
(Figure 5-6). All primary sites have the following: (I) continuous U.S. Geological Survey
(USGS) streamflow gaging; (2) 20 water chemistry samples collected annually over a range of
stream flow conditions (12 base flow and 8 storm flow); (3) nitrogen, phosphorus, and sediment
parameter analyses; and (4) collection techniques that ensure representative samples (CBP 2008).
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Chesapeake Bay TMDL
At secondary sites, all the requirements for primary sites are met except storm sampling
(Figure 5-6). More than 30 of the primary sites are in locations where monitoring has been
coordinated for decades, allowing for trend analysis at the locations. Trend analysis has recently
become possible on the remaining sites as they accumulate the minimum of 5 continuous years
of data.
Monitoring Station
Primary
• Secondary
• River Input
Major Drainage Basins
Eastern Shore MO
§£ Eastern Shore VA
04 Patuxent River
^A4 Potomac River
Rappahannocfc Rivn
_V- Susquehanna River
. Wtelem Shore MO
Yortc River
James River
»"
0 15 90
Source: CBP2010a
Figure 5-6. Chesapeake Bay watershed monitoring network.
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Chesapeake Bay TMDL
The Chesapeake Bay watershed monitoring network is designed to measure the discharge of
nitrogen, phosphorus, and sediment loads from 85 sites in watersheds larger than 1,000 square
kilometers. Routine samples are collected monthly with additional storm-event samples to obtain
a range of discharges and loadings. The seven jurisdictions, the Susquehanna River Basin
Commission, and USGS all use the same set of standardized CBP protocols that are based on
USGS sampling methods and EPA-approved analytical methods (CBP 2008).
5.2.3 Data Quality and Access
The EPA Chesapeake Bay Program Office operates the quality assurance (QA) program that
covers all internal and external Chesapeake Bay Program activities that involve the collection,
evaluation, and/or use of environmental data on behalf of the partnership. The QA program
meets the requirements of EPA Order CIO 2105.0 for EPA programs, i.e., the American National
Standard ANSI/ASQC E4-1994. The QA program also satisfies the requirements of the EPA
Information Quality Guidelines, which describe how EPA organizations meet the Data Quality
Act1 (USEPA 2002b). The CBP Office Quality Assurance Program Management Plan describes
the QA systems and is reviewed regularly and approved by EPA Region 3 (USEPA 2010k).
The CBP partnership has maintained a research-quality monitoring program for Chesapeake Bay
tidal waters since the late 1980s when standardized sampling, analytical, and data management
procedures were developed and coordinated with the then Maryland Office of Environmental
Programs and the Virginia State Water Control Board. River Input Monitoring Program was then
initiated at the major fall lines to measure nutrient and sediment loadings from the watershed's
nine largest rivers and integrated into the QA program. Coordinated water quality monitoring
was later expanded upstream into the free flowing rivers and streams across the Bay watershed,
with seven watershed jurisdictions using comparable protocols (Chesapeake Watershed Partners
2004; CBP 2008).
Each of the partnership's monitoring programs produces a continuous record of high-quality
data. As each of the monitoring programs is designed, in part, to detect trends in water quality
constituents, therefore, trend analyses require very reproducible data over time collected at the
lowest possible limits of detection. Changes in methods, laboratories, instruments, sampling
sites, and such, can affect the results, so changes are carefully evaluated and approved to
preserve the reproducibility of the data sets over time. Data comparability among watershed
jurisdictions is reviewed every 3 months through the Chesapeake Bay Coordinated Split Sample
Program (USEPA 199la). The CBP Office evaluates the accuracy of laboratory data every
3 months by reviewing results of performance evaluation samples, e.g., CBP Blind Audit
Samples2 and USGS Standard Reference Samples.3
1 Section 515(a) of the Treasury and General Government Appropriations Act for Fiscal Year 2001, Public Law
106-554; H.R. 5658.
2 See http://nasl.cbl.umces.edu/.
3 See http://bqs.usgs.gov/srs/.
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Chesapeake Bay TMDL
Online Chesapeake Bay Monitoring Networks data
submission, data access, and quality assurance
resources:
Chesapeake Bay Program Data Hub
http://www.chesapeakebav net/dataandtools.aspx?menuite
m=14872
CBP Water Quality Database
http://www.chesapeakebay.netydata waterqualitv.aspx
CBP Map of Mainstem and Tributary Stations
http://archive.chesapeakebav.net/pubs/maps/2004-149.p_df
CBP Online Water Quality Data Dictionary
http://archive.chesapeakebay.net/data/data dict.cfm?DB C
ODE=CBP WQDB
All federally funded organizations
performing field sampling, laboratory
analysis and/or data analysis as part
of the Chesapeake Bay tidal and
watershed monitoring networks have
KPA-approved QA plans and
standard operating procedures that
conform to the CBP Recommended
Guidelines for Sampling and
Analysis (USEPA 1996). These
guidelines, updated periodically,
reviewed and approved by the CBP
Analytical Methods and Quality
Assurance Workgroup, and then
posted on-line, specify sampling and
analytical methods, precision and
accuracy checks and tolerances, and
documentation requirements. The
QA documents for individual partner
organizations responsible for
components of the larger tidal and
watershed water quality monitoring
networks are on the CBP partnership
website at
http://www.chesapeakehav.net/qualit
yassurance vvq.aspx.
The CBP Office conducts routine
audits of field and laboratory
operations to ensure that the
procedures are carried out according
to their approved QA plans. Several
organizations conduct their own
internal field audits or require the use
of accredited environmental laboratories.
Partners involved in water quality monitoring are required to submit Quality Assurance Project
Plans. Cooperators undergo annual field visits, laboratories cooperative with annual on-site
inspections and participate in quarterly multi-laboratory split sample evaluations to assure
comparability among laboratories. The split samples are surface samples from a location in the
mainstem Chesapeake Bay. Since 1987, within programs of routinely collected data, QA data are
submitted for chemically analyzed parameters in the form of field split samples, lab duplicates,
and lab-spiked samples. Further blind audits are conducted semi-annually.
Guide to Using CBP Water Quality Data
http://archivechesapeakebav.net/pubs/wqusers.pdf
CBP Recommended Guidelines for Sampling and Analysis
http://www.chesapeakebavnet/committee/analvticalmethod
sworkgroup agencies.institutions.andproiects.aspx?menuit
em=16701
CBP Blind Audit Sample Program
http://nasl cbl.umces.edu/
USGS Standard Reference Samples
http://bas.usqs.gov/srs
CBPO Quality Assurance Program
http://www.chesapeakebav.net/qualitvassurance wq.aspx
CBP Analytical Methods and Quality Assurance Workgroup
http://www.chesapeakebav net/committee analvticalmetho
dsworkqroup info.aspx
CBP Data and Information Tracking System
http://archive.chesapeakebav.net/pubs/DAITS 9 21 10.pdf
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Chesapeake Bay TMDL
The Analytical Methods and Quality Assurance Workgroup4 has been part of the CBP
organizational structure since 1988. The workgroup, composed of field sampling team and
laboratory managers provides technical peer reviews of data collection and reporting activities to
ensure consistency among the sampling and analytical organizations (Figure 5-7). The
Workgroup reviews blind audit and coordinated split sample results and identifies potential
causes of observed differences. Special studies or corrective actions might be necessary to ensure
inter-laboratory agreement. If differences are found to affect subsequent data analyses, the
associated bias is quantified and documented in Data and Information Tracking System
(DAITS). DAITS is a registry of technical investigations regarding the quality and use of water
quality data sets.
5.2.4 Data Submission and Quality Assurance
Water quality data are submitted electronically to the CBP Office by the participating data
providers (Figure 5-7) according to data submission requirements specified in the federal
grant/cooperative agreement assistance award provisions (USEPA 201 Ob). Agencies collecting
data as part of the Chesapeake Bay tidal water quality monitoring program submit data to the
Chesapeake Information Management System (CIMS) within 60 days of the end of the month in
which the sample was collected. Watershed streamflow and water quality monitoring data are
submitted once per year. The Data Upload and Quality Assurance Tool (DUQAT) is an
automated online tool available to data submitters who manage the processing of their data
before it is included in the database. DUQUAT proceeds through more than 150 format and QA
checks, provides a report on errors and outliers and, after formal acceptance by the submitter and
CBP data manager, loads the data into the CIMS Water Quality Database. The final report from
the QA-checks is archived and available for future reference. The CIMS Data Upload & Quality
Assurance Tool User's Guide5 gives directions on how to use the tool and shows the correct
table formats (Lane 2004). The database for the Chesapeake Bay watershed monitoring network
is being developed and data submittals from the participating partners will be required to pass
through a modified version of DUQAT before acceptance into the database.
After a water quality data submission has passed through DUQAT, and within 24 hours after
acceptance, the data are added to the Water Quality Database and made available to the public on
the CBP Data Hub.6 The Data Hub interface provides access to several types of data related to
the Chesapeake Bay. It provides links to CBP water quality, living resources (benthic,
phytoplankton, zooplankton), and wastewater treatment and discharging facilities databases, and
external links to partner data sets and databases available on the Data Hub. A data download tool
is available for each CBP database that allows for queries based upon user-defined inputs such as
geographic region and date range. Each query results in a downloadable, tab- or comma-
delimited text file that can be imported to any program (e.g., SAS, Excel, and Access) for further
analysis. About 12,000 sampling events comprising 8,000,000 data records are housed in the
Water Quality Database from 1984 to present that are available to the public (scientists, data
analysts, and private citizens).
4 See http:/7www.chesapeakebay.net/committee_analyticalmethodsworkgroup_info.aspx.
5 See http://archive.chesapeakebay.net/pubs/DUQAlUsersGuide.pdf.
6 See http://www.chesapeakebay.net/dataandtools.aspx?menuitem= 14872.
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Chesapeake Bay TMDL
Program Project
Mainstem& r"
— j Elizabeth R.
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4
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-
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-
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— L£
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[ Va.DEO
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n
Source: Chesapeake Bay Program Office
Figure 5-7. Chesapeake Bay tidal and watershed water quality monitoring networks' participants arrayed by
their role in sample collection, laboratory analysis, and/or data reporting.
Laboratory Abbreviations:
CBL - University of Maryland Chesapeake Biological Laboratory
DCLS - Virginia Department of Consolidated Laboratory Services
DHMH - Maryland Department of Health and Mental Hygiene
DNREC - Delaware Department of Natural Resources and Environmental Quality
DNREC ESL - Delaware Natural Resources Environmental Laboratory Services
Md. DNR - Maryland Department of Natural Resources
NWQL - National Water Quality Laboratory
NYSDEP - New York State Department of Environmental Conservation
ODU - Old Dominion University Water Quality Laboratory
PADEP - Pennsylvania Department of Environmental Protection
SRBC - Susquehanna River Basin Commission
USGS - United States Geological Survey (Md., Pa., Va. & W.Va. Water Science Centers)
Va. DEQ - Virginia Department of Environmental Quality
VIMS - Virginia Institute of Marine Science
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Chesapeake Bay TMDL
All required data submissions from the monitoring programs described must meet the data
requirements set forth in the Chesapeake Bay Program Guidance and Policies for Data,
Information and Document Outputs Submission (USEPA 201 Ob). All living resources data
deliverables are sent in a format compliant with Appendix E of the 2000 Users Guide to Living
Resources Data when submitted to the CBP (USEPA 2000).
Database documentation and metadata links for the various sampling programs are available for
viewing and download. A map of mainstem and tributary monitoring stations7 is available and
helps users query for data in a specific geographic region of the watershed. The Guide to Using
CBP Water Quality Monitoring Data describes the Chesapeake Bay tidal water quality
monitoring program in general and provides detailed information about the existing database
(CBP 201 Ob). The Water Quality Database Design and Data Dictionary is a resource that
defines the development of the database and provides a detailed description of the tables and data
in the database (CBP 2004b). The online version of the Water Quality Data Dictionary provides
the up-to-date CIMS and CBP codes used in the Water Quality Database.
5.2.5 Monitoring Applications in Chesapeake Bay TMDL Development
Data collected through the Chesapeake Bay tidal and watershed monitoring networks over the
last three decades, described above, have been applied in numerous ways, supporting the
development of the Bay TMDL:
• Used to develop the original Chesapeake Bay segmentation scheme and its subsequent
refinements (USEPA 1983b, 2004b, 2005)
• Used in derivation of the DO, water clarity, SAV restoration acreage, and chlorophyll a
criteria published by EPA on behalf of the partnership (USEPA 2003a)
• Used in the delineation of the spatial boundaries of the five Chesapeake Bay tidal water
designated uses (USEPA 2003d. 2004e, 2010a)
• Used in the original development and ongoing refinement of the Chesapeake Bay water
quality criteria assessment procedures (USEPA 2003a, 2004a, 2007a, 2007b, 2008a,
2010a)
• Used by four Bay jurisdictions to assess achievement of their respective Chesapeake Bay
WQS regulations and development of their section 303(d) lists (USEPA 2007a)
• Used in the development, calibration, verification and management application of the Phase
5.3 Chesapeake Bay Watershed Model and Chesapeake Bay Water Quality Model (Cerco
and Noel 2004; Cerco et al. 2010; USEPA 2010J)
5.3 MODELING FRAMEWORK OVERVIEW
Since the early 1980s, the CBP partnership has developed and applied multiple generations of
linked environmental models to help evaluate the response of Chesapeake Bay water quality to a
multitude of pollutant control management scenarios and programmatic approaches (Figure 5-8).
7 See http://archive.chesapeakebay.net/pubs/maps/2004-149.pdf.
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Chesapeake Bay TMDL
BMP Dalu
LUData
Point Sources
Data
Septic Dm
U.S. C«n»u> Only
Precipitation
Meteorological Data
Elevation Data
Soil Data
„ ALLOCATION
MITHODOLOCY
Figure 5-8. Chesapeake Bay TMDL modeling framework.
The fourth and fifth generations of some of these environmental models have been applied to
support development of the Chesapeake Bay TMDL.
The Chesapeake Bay models are state-of-the-science and played a pivotal role in the
development of the Bay TMDL. However, these models are just one of the tools in the TMDL
analysis that also includes monitoring and environmental research. The models produce
estimates, not perfect forecasts. Hence, they reduce, but do not eliminate, uncertainty in
environmental decision making. Used properly, the suite of Bay models provide best estimates
for developing nitrogen, phosphorus, and sediment reductions that are most protective of the
environment. Ultimately, the Chesapeake Bay TMDL was based on the overall corroboration of
the suite of Chesapeake Bay models, the Bay tidal and watershed monitoring networks, and
environmental research.
The two major components of the Chesapeake Bay TMDL modeling framework are the Phase
5.3 Chesapeake Bay Watershed Model (Bay Watershed Model) and the Chesapeake Bay Water
Quality and Sediment Transport Model (Bay Water Quality Model). Several other models and
tools were used to provide critical inputs or to facilitate parameterizing (i.e., selecting the model
components and their attributes that best describe the relevant characteristics of the watershed)
the Bay Watershed Model to run various management scenarios (Table 5-1).
The models used to develop the Chesapeake Bay TMDL simulate the same 10-year hydrologic
period from 1991 to 2000. The models are linked together so that the output of one simulation
provides input data for another model (Figure 5-8). For example, the nitrogen outputs from the
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Chesapeake BayTMDL
Chesapeake Bay Airshed Model affect the nitrogen input from atmospheric deposition to the Bay
Watershed Model. The Bay Watershed Model, in turn, transports the total nitrogen, phosphorus,
and sediment loads, including the contributions from atmospheric deposition, to the Bay Water
Quality Model. The Bay Water Quality Model, in turn, simulates the effects of the nitrogen,
phosphorus, and sediment loads generated by the Bay Watershed Model and the effects of direct
atmospheric deposition to tidal surface waters on Bay water quality (e.g., DO, water clarity,
chlorophyll a), exchange of nitrogen, phosphorus, and oxygen with bottom sediment, and living
resources (e.g., underwater Bay grasses, algae, microscopic animals, bottom sediment dwelling
worms and clams, oysters, and menhaden).
Table 5-1. Modeling tools supporting development of the Chesapeake Bay TMDL
Model
Chesapeake Bay Airshed Model
Chesapeake Bay Land .Change Model,
Version 4
Chesapeake Bay Spatially Referenced
Regressions on Watershed Attributes
(SPARROW) Model '
Chesapeake Bay Scenario Builder
Phase 5.3 Chesapeake Bay
Community Watershed Model
Chesapeake Bay Water
Quality/Sediment Transport Model
Chesapeake Bay Criteria Assessment
Program
Chesapeake Bay Climate Change
Simulation
Function
Provides estimates of wet and dry atmospheric deposition to
the Bay watershed and Bay water quality models
Provides annual time series of land uses to the Bay
Watershed Model as well as projects land uses out to 2030
Provides a general calibration check on the Bay Watershed
Model's land use and riverine loads
Facilitates the creation of input decks for Bay Watershed
Model management scenarios
Simulates loading and transport of nitrogen, phosphorus, and
sediment from pollutant sources throughout the Bay
watershed
Provides estimates of watershed nitrogen, phosphorus, and
sediment loads resulting from various management scenarios
Simulates estuarine hydrodynamics, water quality, sediment
transport, and key living resources such as algae,
microscopic animals, bottom sediment dwelling worms and
clams, underwater grasses, and oyster and menhaden filter
feeding
Predicts Bay water quality resulting from various management
scenarios
Ensures allocated loads under the Bay TMDL will meet
jurisdictions' Bay water quality standards
Assesses attainment of the jurisdictions' Bay water quality
standards using a unique combination of Bay Water Quality
Model management scenario outputs and Bay water quality
monitoring data
Uses aspects of downscaled data from a suite of Global
Climate Models, the Bay Watershed Model, and the Bay
Water Quality Model to simulate climate change effects in the
Chesapeake Bay and its watershed
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Chesapeake Bay TMDL
The following sections provide additional details about each of the Bay models and other
decision support tools used in development of the Chesapeake Bay TMDL and the linkages
between the various models and tools. For each model/tool, the sections provide a general
description of the model and how it was used in developing the Chesapeake Bay TMDL. Links
to more detailed, online documentation are provided. Appendix B contains a more extensive list
of Bay model related documentation, reports, independent scientific peer reviews, and model
scenario inputs and outputs all with links for on-line access.
5.4 CHESAPEAKE BAY AIRSHED MODEL
The Chesapeake Bay Airshed Model (Bay Airshed Model) provides estimates of nitrogen
deposition resulting from changes in emissions from utility, mobile, and industrial sources
because of management actions or growth.
The Bay Airshed Model was used to provide inputs of nitrogen from wet and dry deposition to
the Bay Watershed Model and to the Bay Water Quality Model. The Bay Airshed Model is
linked to the Bay Watershed Model through atmospheric deposition to land surfaces and free
flowing streams and rivers and to the Bay Water Quality Model through direct atmospheric
deposition to the tidal surface waters of Chesapeake Bay (USEPA 2010J).
The Bay Airshed Model combines a wet deposition regression model (Figure 5-9) (Grimm and
Lynch 2000; 2005), and a continental-scale air quality model of North America called the
Community Multiscale Air Quality Model (CMAQ) for estimates of dry deposition (Figure 5-10)
(Dennis et al. 2007; Hameedi et al. 2007). Wet deposition occurs during precipitation events and
contributes to the loads only during days of rain or snow. Dry deposition occurs continuously
and is input at a constant rate every day.
The CMAQ scenarios include the management actions required by the Clean Air Act (CAA) in
2010, 2020, and 2030. The future year scenarios reflect emissions reductions from national
control programs for both stationary and mobile sources, including the Clean Air Transport Rule
(Replacement for the Clean Air Interstate Rule), the Tier-2 Vehicle Rule, the Nonroad Engine
Rule, the Heavy-Duty Diesel Engine Rule, and the Locomotive/Marine Engine Rule (see Section
6.4.1 and Appendix L for more details).
The CMAQ provides monthly constants for dry deposition. It requires a variety of input files that
contain information pertaining to the entire North American continent. Those include hourly
emissions estimates and meteorological data in every grid cell and a set of pollutant
concentrations to initialize the model and to specify concentrations along the modeling domain
boundaries. The initial and boundary concentrations were obtained from output of a global
chemistry model.
The CMAQ simulation period is for one year, 2002, characterized as an average deposition year.
The 2002 CMAQ simulation year was used to provide the monthly dry deposition estimate for
each year of Bay model simulation from 1985 to 2010.
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Chesapeake Bay TMDL
Monitoring Program
A AIRMoN
• NADP/NTN
Source: Grimm and Lynch 2005
Figure 5-9. Atmospheric deposition monitoring stations used in the Chesapeake Bay airshed nitrogen wet
deposition regression model.
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Chesapeake Bay TMDL
Chesapeake Watershed
fj Phase 5.3 Domain
"J CMAQ 12 km Grid
Source: USEPA 201 Oj
Figure 5-10. The Community Multiscale Air Quality Model's 12 km grid over the Phase 5.3 Chesapeake Bay
Watershed Model county segmentation.
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December 29, 2010
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Chesapeake Bay TMDL
The wet deposition regression model provides hourly wet deposition loads to each land-segment
on the basis of each land-segment's rainfall. The regression model uses 29 National Atmospheric
Deposition Program monitoring stations and 6 AIRMoN stations to form a regression of wetfall
deposition across the entire Phase 5 Chesapeake Bay Watershed Model domain over the entire
simulation period (see Appendix L).
To account for wet deposition of nitrogen, EPA both developed a specific TMDL load allocation
(LA) for the direct nitrogen atmospheric deposition onto the tidal surface waters of Chesapeake
Bay and accounted for air deposition of nitrogen to the Bay watershed in the LAs of the
watershed-based sources. The Bay TMDL air load allocation reflects the modeled atmospheric
nitrogen deposition to the tidal surface waters of the Bay, taking into account the reduction in air
emissions expected from sources regulated under existing or planned federal CAA authorized
programs (see Section 6.4.1 and Appendix L).
Detailed information related to the Bay Airshed Model and its application in development of the
Chesapeake Bay TMDL is available in Section 5 of the Phase 5.3 Chesapeake Bay Watershed
Model Report (USEPA 201 Oj) at
http://wvvw.chesapeakebay. net/model jphase5.asp.\?menuitein=26169.
5.5 CHESAPEAKE BAY LAND CHANGE MODEL
The Phase 5.3 Chesapeake Bay Watershed Model makes use of annually changing land use
profiles derived from the Chesapeake Bay Land Change Model.
5.5.1 Motivations for Developing Future Land Use Estimates
A major challenge facing water resource managers today is how to maintain progress restoring
the Chesapeake Bay in the face of continued population and urban development. The
Chesapeake Bay Land Change Model (Bay Land Change Model) was developed to help address
this management challenge. In conjunction with the Bay Watershed Model, the Bay Land
Change Model can be used to assess potential future changes in nitrogen, phosphorus, and
sediment loads to the Bay.
5.5.2 Scale of Chesapeake Bay Land Change Model Future Land Use
Estimates
To meet the data requirements of Bay Watershed Model, the Bay Land Change Model forecasts
change at the Bay Watershed Model segment scale. Version 4 of the Bay Land Change Model
includes more than 2,000 modeling segments (e.g., polygons) in the Bay watershed and
intersecting counties (Figure 5-11). The segments were created on the basis of an intersection of
county boundaries, major topographic divides, and a 1:250,000 scale river reach drainage area
network. Because the modeling segments are within counties, all data generated at the modeling
segment scale can also be provided at the county scale for local review and comment.
5-24 December 29, 2010
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Chesapeake Bay TMDL
Source: Irani and Claggett 2010
Figure 5-11. 2006 Land cover conditions in the Chesapeake Bay watershed and intersecting counties.
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December 29, 2010
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Chesapeake Bay TMDL
5.5.3 Components of Chesapeake Bay Land Change Model Future Land
Use Estimates
In support of the CBP management concerns, researchers from USGS. HPA. Shippenshurg
University, and a private consultant developed the Chesapeake Bay Land Change Model, which
combines the strengths of a growth allocation model or (iAMe (Reilly 2003), with those of a
cellular automata model, SLEUTH (slope, land use, excluded land, urban extent, transportation,
and hillshade) (Clarke et al. 1997: Jantz et al. 2003). GAMe projects future urban developed area
at the Bay Watershed Model segment scale by fitting total housing unit trends over the 1990s to
a Gompertz (exponential S-shaped) Curve that is then used to extrapolate housing trends to the
year 2030. County population projections converted to county scale estimates of total housing
demand are used to constrain the modeling segment scale forecasts £o\etaVe
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Chesapeake Bay TMDL
process generates relative proportions of future growth by land cover class for each modeling
segment. Multiplying those proportions by the acreage of forecasted growth (generated by
GAMe) determines how much acreage to subtract or add in future years to the Phase 5.3 Bay
Watershed Model 2002 baseline land use classes.
The Bay Land Change Model also includes a Sewer Model to estimate the population on sewer
and septic in the years 2000 and 2030. Where local data were not available, a population density
raster data set derived from year 2000 Census Block Group data and detailed road vector files
were used to represent probable sewered areas in the year 2000. The approach captures 81
percent of Maryland's mapped residential sewered areas on the basis of a one-to-one cell
comparison. That approach also compares favorably with survey data in Virginia representing
households with sewer service in the 2001 to 2005 period.
Modeled sewered areas in the year 2000 were expanded along existing roads by 300 in to 2,000
in to represent possible expansion of the sewer network through the year 2030. Forecasted
population values for each watershed modeling segment were derived by converting the housing
demand forecasts into estimates of future population. Future populations on sewer and septic
were estimated by overlaying the SLEUTH probability map onto the modeled sewer service
areas for 2030 to derive proportions of growth on sewer and septic, which were then multiplied
by the forecasted population in each modeling segment. The proportions of growth on sewer and
septic were kept constant for all interim year forecasts between 2000 and 2030. The percent
change in population within each sewer service area was used to estimate the percent change in
flow for all wastewater treatment plants in or close to each service area.
More detailed information on the Chesapeake Bay Land Change Model and its application in the
C'hesapeake Bay TMDL is available in Section 4 of the Phase 5.3 Chesapeake Bay Watershed
Model Report (USEPA 2010J) at
http://ww\s.chesapeakebav. net/model j}hase5.aspx?menuitem=26169.
5.6 CHESAPEAKE BAY SPARROW MODEL
The USGS developed a set of spatially referenced regression models to provide additional spatial
detail on nutrient sources and transport processes in the Bay watershed. The SPARROW
(SPAtially Referenced Regression On Watershed Attributes) model integrates monitoring data
with landscape information and uses statistical methods to relate water-quality monitoring data to
upstream sources and
watershed characteristics that
affect the fate and transport of
constituents to streams,
. ,- • • SPARROW fact sheet
estuaries and other receiving http://Dubs usas.QOV/fs/2QQ9/3019/
waterbodies (Preston et al.
2009). SPARROW is
For additional information on Chesapeake Bay SPARROW
modeling, see the following resources:
National SPARROW home page
... j i . •„.,„ i http://waterusgs.gov/nawqa/sparrow/
watershed based and designed — — —
Chesapeake Bay Specific
http://md.water.usgs.gov/publications/wrir-99-4054/html/index.htm
for use in predicting long-term
average values such as
«™ntr!itmn« anH Slivered http://md.water.usQS.QOv/publications/ofr-2004-1433/
concentrations and delivered http://chesapeakeusgs.gov/coast/restorationmapper.html
loads to downstream receiving
5-27 December 29, 2010
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Chesapeake Bay TMDL
waters. Statistical methods are used to explain in-stream measurements of water quality in
relation to upstream sources and watershed properties (e.g., soil characteristics, precipitation, and
land cover).
Among its outputs, the SPARROW model can be used to quantify incremental yield or edge-of-
field loading, which is the amount (load per area) of total nitrogen, phosphorus, or sediment
generated in each reach basin independent of upstream load (Figure 5-12). The Chesapeake Bay
SPARROW models provide loading information for three separate periods, the late 1980s, the
early 1990s, and the late 1990s (Brakebill et al. 2010; Brakebill and Preston 2004, 2007; Preston
and Brakebill 1999). For the Chesapeake Bay watershed modeling and TMDL development
effort, EPA used the results of the SPARROW model as a data source for estimating average
edge-of-field targets when developing and calibrating the Phase 5.3 Chesapeake Bay Watershed
Model(USEPA20IOj).
EXPLANATION
tXPI-ANATION
I Al O.lnii.d r»M ol total •*.»••
du» to poirt wurtM
IBI 0«li«.,«i ri
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Chesapeake Bay TMDL
designed so that users may select an area of one or more counties, the livestock types, and the
number of animals, along with a land use using the 25 Watershed Model-HSPF categories and
then be able to alter the crop mix that is nested in each of the agricultural land uses along with
BMPs.
• MPType and
location
(NEIEN/State
supplied)
• Land acres
• Remote Sensing,
NASS Crop land
Data layer
• Crop acres
• Yield
• Animal Numbers
(Ag Census or state
supplied)
• Land applied
biosolids
• Septic system (fls)
Parameters
(Changeable by user)
• BMP types and efficiencies
• Land use change (BMPs, others)
• RUSLE2 Data: % Leaf area and
residue cover
• Plant and Harvest dates
• Best potential yield
• Animal factors (weight, phytase
feed, manure amount and
composition)
• Crop application rates and timing
• Plant nutrient uptake
• Time in pasture
• Storage loss
• Volatilization
• Animal manure to crops
• N fixation
• Septic delivery factors
• BMPs, # and
location
• Land use
• % Bare soil,
available to
erode
• Nutrient uptake
• Manure and
chemical
fertilizer
(Ib/segment)
• N fixation
(Ib/segment)
• Septic loads
Outputs
Figure 5-13. Scenario Builder conceptual process.
Scenario Builder estimates the amount of nitrogen and phosphorus load that will be generated b>
a given land use in the presence of agricultural and other land-based activities and estimates the
area of soil available to be eroded. Loads are input to the Bay Watershed Model to generate
modeled estimates of loads delivered to the Bay. Additional information related to Scenario
Builder and its application in Bay TMDL development (USEPA 2010d) is at
hnP;//archive.chesapeakebav.net7Dubs/SB V22 Final 12 31 2010.pdf.
For the Bay TMDL, Scenario Builder was used to provide the land use-based scenario inputs to
the Phase 5.3 Chesapeake Bay Watershed Model. The seven watershed jurisdictions will
continue using it when implementing their Watershed Implementation Plans to build model
scenarios of their actual and future implementation practices that will, in turn, be run through the
Bay Watershed Model to track implementation status and project future implementation rates.
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December 29, 2010
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Chesapeake Bay TMDL
5.8 PHASE 5.3 CHESAPEAKE BAY WATERSHED MODEL
The Phase 5.3 Chesapeake Bay Watershed Model is an application of the Hydrologic Simulation
Program-Fortran (HSPF) (Bicknell et al. 2005). The segmentation scheme divides the
Chesapeake Bay watershed into approximately 1,000 segments/subbasins. with the average size
about 64 square miles. About 280 monitoring stations throughout the Chesapeake Bay watershed
were used for calibration of hydrology, while approximately 200 monitoring stations were used
to calibrate water quality, depending on the constituent being calibrated. There are 530 river-
segments with simulated reaches that drain to a simulated downstream reach. There are 62 river-
segments with simulated reaches that drain directly to the Chesapeake Bay and 379 river-
segments adjacent to tidal waters that are without a simulated reach (Figure 5-14).
The Bay Watershed Model simulation period covers 21 years from 1984 to 2005 to take
advantage of more recent and expanded monitoring data and information. The expansion of the
model period to a 21-year period resulted in a more representative and improved land use
inventory for use in model calibration. While the Phase 4.3 Bay Watershed Model and all
previous Bay watershed model versions had a constant land use. the Phase 5.3 Bay Watershed
Model allows a time series of land use input data to change annually over the 1984 to 2005
simulation period (USEPA 2010J).
As a community model, the Phase 5.3 Bay Watershed Model has open source model code,
pre-processors, post-processors, and input data that are freely available to the public (USFPA
2010J). Input data include precipitation information, municipal and industrial wastewater
treatment and discharging facilities, atmospheric deposition, and land use (USFPA 201 Oj). By
offering the Bay Watershed Model as a community model, end users—typically TMDI. model
developers and watershed researchers and implementation plan developers—can use the model
independently as is or as a starting point for more detailed, small-scale models (USEPA 2010J).
The Phase 5.3 Chesapeake Bay Watershed Model can be downloaded from this ftp site:
ftp://ftp.chesapeakebav.net/Modeling/phase5/community/ or the Chesapeake Community
Modeling Program's website at
http://ches.comnuinitvmodcling.org/models/CBPhase5/datalibrarv.php.
The Bay Watershed Model simulates the 21-year period (1984-2005) on a one-hour time step
(USEPA 2010J). Nutrient inputs from manure, fertilizers, and atmospheric deposition are based
on an annual time series using a mass balance of U.S. Census of Agriculture animal populations
and crops, records of fertilizer sales, and other data sources. BMPs are incorporated on an annual
time step and nutrient and sediment reduction efficiencies are varied by the si/e of storms.
Municipal and industrial wastewater treatment and discharging facilities and onsite wastewater
treatment systems' nitrogen, phosphorus, and sediment contributions are also included in the Bay
Watershed Model. The following sections provide additional details regarding the underlying
data used to develop and calibrate the Bay Watershed Model.
5.8.1 Bay Watershed Model Segmentation
In many HSPF applications, the river segmentation and the land segmentation is the same. Each
river segment will have a set of land uses that drain to it and it only. In the Phase 5.3 Chesapeake
Bay Watershed Model, the segmentation schemes are separate (USEPA 20lOj). Land segments
are generally county-based because a simulation of a representative acre of each land use type
5-30 December 29, 2010
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Chesapeake Bay TMDL
Adjacent to tidal water;
no simulated reach
Drains directly to the Bay;
simulated reach
Simulated reach;
drains to downstream simulated reach
Source: USEPA2010J
Figure 6-14. Segmentation and reach simulation of the Phase 5.3 Chesapeake Bay Watershed Model.
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December 29, 2010
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Chesapeake Bay TMDL
exists in each county. Some counties in mountainous regions where the rainfall patterns varied
significantly have been broken out into several land segments. The segments that result from the
intersection of the two segmentation schemes are known as land-river segments (Martucci et al.
2006).
5.8.2 Bay Watershed Model Setup
Detailed information related to how the Bay Watershed Model was set up to support
development of the Bay TMDL is available in the Phase 5.3 Chesapeake Bay Watershed Model
Report (USEPA 2010J). In addition, information related to model representation of land use-
related nutrient generating sources is available in the Scenario Builder documentation (USEPA
2010d). The following paragraphs provide a general description of critical data components
underlying the Bay Watershed Model.
Meteorological Data
Meteorological data are critical inputs to the Bay Watershed Model because precipitation is a
primary driver of nitrogen, phosphorus, and sediment loadings to the Bay. Approximately 500
daily data and 200 hourly data precipitation monitoring stations were used in development and
calibration of the Phase 5.3 Chesapeake Bay Watershed Model (USEPA 201 Oj). Precipitation is
derived from an hourly output regression model of these stations developed by USGS.
Meteorological parameters included in the simulation are hourly temperature, solar radiation,
wind speed, daily dew point, cloud cover, and potential evapotranspiration. Those parameters
were collected from the seven primary meteorological stations in the Chesapeake Bay watershed
(USEPA 201 Oj).
Withdrawals
Water withdrawals are represented in the Bay Watershed Model as daily amounts from
jurisdictions' reported data of monthly or annual withdrawals. Water withdrawals include
irrigation use and thermoelectric use, among others. The Bay Watershed Model also takes into
account the seasonal cycle of irrigation use. Consumptive uses are modeled as 100 percent
removal of the water from the appropriate stream segment, and any resulting wastewater is
treated as a separately modeled point source discharge (USEPA 2010J).
Soils and Sediment
Soil characteristics were obtained from the Natural Resources Conservation Service's
Interpretation Records and the National Resources Institute. Sediment delivery from each land
use is based on National Resources Institute's estimates of annual edge-of-field sediment loads,
as determined by the Revised Universal Soil Loss Equation (USEPA 2010J).
Land uses
The Phase 5.3 Chesapeake Bay Watershed Model simulates 24 land uses, including 11 types of
cropland, 2 types of woodland, 3 types of pasture, 5 types of developed land, and provisions for
other special land uses such as surface mines and AFOs (Table 5-2) (USEPA 2010J). Nitrogen
and phosphorus in the major pervious land uses of woodland, cropland, hay, pasture, and
developed pervious are simulated using the AGCHEM modules in HSPF that fully simulate
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Chesapeake BayTMDL
forest or crop nutrient cycling, including uptake by plants. The minor pervious land uses, which
are harvested forest, land under construction, nurseries, surface mines, and degraded riparian
pasture, are simulated through PQUAL, which represents nutrient export through concentration
coefficients. Impervious land uses are simulated through the 1QUAL modules, which use
accumulation and wash-off coefficients to simulate nutrient and sediment export.
The final Phase 5.3 land use is available as a sub-county tabular database for the years 1985,
1987, 1992, 1997, 2002, and 2005 at
ftp://ftp.chcsapeakebav.net/Modeling/phase5/Phase%205.3%20Calibration/IVl odelQ/o20lnput/land
_use.zip. The Phase 5.3 model input decks including the land use files above are also linked with
a brief explanation from the Phase 5 Model page at
http://www.chesapeakebay.net/model phase5.asp.\. The Bay Watershed Model uses a
continuous time series of land use interpolated from those years.
The principal databases used to develop the Phase 5.3 Bay Watershed Model, 30-meter land use
coverage were the following:
• USGS Chesapeake Bay Land Cover 1984, 1992, 2001 and 2006 Data Series (CBLCD)
• County level U.S. Census of Agriculture 1982, 1987. 1992, 1997. 2002. and 2007 data
• 2001 Impervious Surface Land Cover data developed by the University of Maryland's
Regional Earth Science Applications Center (RESAC) (Goetz et al. 2004)
• Ancillary data from the jurisdictions were used to develop the extractive land use cover,
including spatial and tabular permitting information
• Construction land use is a percentage of impervious change
Table 5-2 provides a summary of the land use types modeled by the Phase 5.3 Bay Watershed
Model, the specific land uses, and a basic description of their derivation. Additional detail is
available in Section 4 of the Phase 5.3 Chesapeake Bay Watershed Model report (USEPA 2010J)
at http://www.chcsapeakebay.net/inodel phase5.aspx?menuitem-26169.
Table 5-2. Phase 5.3 Chesapeake Bay Watershed Model land uses
Land use type
Agricultural
Land use
Pasture
Degraded
riparian pasture
Nutrient
management
pasture
Description
Based on pastureland areas from the
agricultural census
Unfenced riparian areas where
livestock have stream access;
represents a portion of the pasture
use
Pasture that is part of a farm plan
where crop nutrient management is
practiced. Nutrient management
pasture is pasture that receives
manures that are excess on a farm
after all crop nutrient needs are
satisfied
Source
USDA Agricultural Census
A unique area designated
by each state as the acres
of planned riparian
pasture fencing in their
Tributary Strategies
Derived from the pasture
land use and state nutrient
management BMP
tracking data
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Land use type
Woodland
Developed
Land use
Alfalfa hay
Hay-unfertilized
Hay-fertilized
Conventional
tillage with
manure
Conventional
tillage without
manure
Conservation
tillage without
manure
Nursery
Animal Feeding
Operations
Forest, woodlots,
and wooded
Harvested forest
High-density
pervious
Description
Alfalfa is a separate hay category
because it is a nitrogen-fixing,
leguminous crop and receives
different nutrient applications than
other hay crops
(Wild hay) + (cropland idle) +
(cropland in cultivated summer fallow)
(Hay-alfalfa, other tame, small grain,
wild grass, silage, green chop, act) -
(wild hay) - (alfalfa) + (cropland on
which all crops failed)
Wheat, barley, buckwheat, sunflower,
corn, sorghum, soybeans and dry
beans
(Cotton) + (tobacco) + (land used for
vegetables) + (potatoes, excluding
sweet potatoes) + (sweet potatoes) +
(berries) + (nursery acres in the open)
+ (land in orchards)
Crops typically grown for direct
human consumption (such as cotton,
tobacco, vegetables, potatoes and
berries) and field nurseries
Container nurseries, which typically
have a high density of plants (1 0-1 00
plants per square meter) and high
rates of nutrient applications
Percentage of pastureland, based on
animal populations from the
agricultural census
Includes woodlands, woodlots,
wetlands and usually any wooded
area of 30 meters by 30 meters
remotely sensed by spectral analysis.
Predominant land use in watershed.
Estimated at 1% of forest, woodlots,
and wooded land use
High-Intensity Pervious Developed
(Hp) lands are immediately adjacent
to High-Intensity Impervious
Developed lands and include mostly
small landscaped areas and lands
adjacent to developed structures and
major roadways. No portions of these
ands are impervious
Source
USDA Agricultural Census
USDA Agricultural Census
USDA Agricultural Census
USDA Agricultural Census
USDA Agricultural Census
USDA Agricultural Census
USDA Agricultural Census
Derived from the USDA
Agricultural Census count
of farms and the type and
numbers of animals
Largely derived from the
land area the was not
developed, not in the
USDA Agricultural
Census, and not water of
lakes and rivers
Derived from the forest,
woodlots, and wooded
land use
Derived from satellite data
and density of road
network
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December 29, 2010
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Chesapeake Bay TMDL
Land use type
Minor Land
uses
Land use
High-density
impervious
Low-density
pervious
Low-density
impervious
MS4
Bare-construction
Extractive-Active
and Abandoned
Mines
Open Water
Description
High-Intensity Impervious Developed
(Hi) lands contain more than 50%
impervious surfaces per quarter-acre
(on average) and generally represent
impervious surfaces .associated with
large structures and major roads and
include mostly commercial, industrial,
and high-density residential land
uses, interstates, and other major
roads.
Low Intensity Pervious Developed
(Lp) lands are generally associated
with Low-Intensity Impervious
Developed lands and include
residential lawns, golf courses,
cemeteries, ball fields, developed
parks, and other developed open
spaces. Any impervious surfaces
associated with these land uses are
captured in either the low-intensity or
high-intensity impervious developed
classes depending on the size of the
structure or road.
Low-Intensity Impervious Developed
(Li) lands contain less than 50%
impervious surfaces per quarter-acre
(oh average) and generally represent
impervious surfaces associated with
small structures and minor roads and
include mostly low to medium density
residential areas and some sidewalks
and driveways.
Developed land coincident with an
area requiring Municipal Separate
Storm Sewer System (MS4) permits.
Based on the difference between the
RESAC impervious land estimates of
1990 and 2000. Impervious land,
which increased over the 10-year
period, was assumed to have
transitioned from a bare-construction
land use
Mines, gravel pits and areas affected
by mine-related activities. In Virginia,
acres are based on permit
information; all others are based on
RESAC data
Nontidal waters, acreage constant
throughout model period
Source
Derived from satellite data
and density of road
network
Derived from satellite data
and density of road
network
Derived from satellite data
and density of road
network
Derived from state
regulatory data
Derived from a
combination of impervious
area and construction
permits
State permitting data
Satellite-derived estimate
Source: USEPA 201 Oj
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Chesapeake Bay TMDL
Agricultural Land Uses
Satellite-derived estimates of cropland and pasture have higher uncertainty in the prediction of
the extent of these land cover classes compared to the USDA Agricultural Census data in certain
land-river segments, so census data were used to inform and modify the extent of these land uses.
County-level total agricultural land use information from the USDA Agricultural Census data .
were interpolated to the base years of 1990 and 2000. Agricultural land use was distributed to the
model segments by the ratio of census agricultural classes for each county, and other land uses
were distributed in the remaining model segment area in proportion to their acreage in the
county. Annual changes in land use were linearly extrapolated or interpolated from the 1990 and
2000 base years and years covered in the USDA Agricultural Census (1982, 1987, 1992, 1997,
2002, and 2007), resulting in annual sub-county data sets of land use.
The total agricultural area was split into different agricultural land uses, bythe average ratio of
crops in the USDA agricultural census. Crops were aggregated by similar surface cover
characteristics and fertilizer application rates to yield categories with similar nutrient-loading
properties.
State agricultural engineers provided fertilizer and manure application timing and rates, crop
rotation information, and field operation timing information. Manure application is represented
in a time-varying mass balance of manure nutrients, according to animal population and
predominant manure handling practices (USEPA 2010J).
Animal waste areas are defined by manure acres, which allows for the simulation of high nutrient
content runoff, and are based on the population of different animal types. The manure acres in a
given area change based on the number of animals of each type (beef and dairy cattle, swine,
laying hens, broilers and turkeys) and the implementation of animal waste management systems.
Nutrient export is simulated as a concentration applied to the runoff from the manure acres
(USEPA 20lOj).
Urban Land Uses
For urban land representation, high- and low-density development and the proportion of
impervious and pervious area were mapped for 1990 and 2000 (USEPA 2010J).
Other Land Uses
Other land uses represented in the model include construction, which typically has high sediment
loading capacity; extractive-active and abandoned mines; and open non-tidal water.
Future Land Use Estimations
The Chesapeake Bay Land Change Model was developed to help assess potential future changes
in nutrient and sediment loads to the Bay resulting from land use changes (see Section 5.5 and
Section 10.1).
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5.8.3 Pollutant Source Representation
The Bay Watershed Model represents various sources of nitrogen, phosphorus, and sediment on
the basis of the characteristics of the source and information available for characterizing the
source. Point sources such as permitted wastewater and industrial dischargers that generally
discharge continuously are represented directly in the Bay Watershed Model using locational
data, flow, and discharge characteristics. Other sources, such as septic systems or agricultural
activities, are represented in the model through the underlying land use coverage and
assumptions related to nitrogen, phosphorus, and sediment production from associated land uses.
Those sources can be thought of as land use-related sources because the simulation of their
loading characteristics is driven by the land use categories with which they are associated.
Several such land use-related sources are subject to National Pollutant Discharge Elimination
System (NPDES) permits. An example of such a land use-related source is an municipal separate
storm sewer system (MS4) area, which is subject to an NPDES permit and must receive a WLA
in the TMDL, but loadings are derived as a function of the modeled land use loading rates for
associated land uses (e.g., urban pervious land). The following paragraphs summarize the Bay
Watershed Model's representation of the major sources of nitrogen, phosphorus, and sediment to
the Bay. Additional minor land use sources are also detailed in the Phase 5.3 Chesapeake Bay
Watershed Model Report (USEPA 2010J).
Municipal and Industrial Discharges
Municipal and industrial discharges are considered direct inputs to the river reaches. In the Bay
Watershed Model, the river segments are simulated as a completely mixed reactor, and all the
wastewater discharged loads within a reach are summed for each of the river segments and input
as a daily load (USEPA 201 Oj).
Concentrated Animal Feeding Operations (CAFOs)
CAFOs are represented in the model as part of the AFO land use, which represents the
production area of livestock operations. The loading is calculated on the basis of animal counts;
manure nutrients production rate modified by feed considerations; time spent in pasture out of
the production area; volatilization factors; and loss coefficients, which are dependent on storage
facility type. The full description of the CAFO and AFO land use loads is available in the
Scenario Builder documentation (USEPA 2010d) at
http://archive.chesapeakebav.net'pubs/'SB V22 Final 12 31 2010.pdf.
Combined Sewer Overflows (CSOs)
CSO loads are not directly simulated by the Bay Watershed Model. CSO loads for the TMDL
were developed using estimations of daily CSO flows and nutrient concentrations for the CSO
communities in the watershed. For details related to how the CSO loads were calculated, see
Section 7 of the Phase 5.3 Chesapeake Bay Watershed Model Report (USEPA 2010J) at
http://wwvv.chesapeakebav.net/model phase5.aspx?menuitem=26169.
MS4s
The estimated MS4 areas were provided by each of the jurisdictions and represent the current
understanding of MS4 areas. While the best and final definition of an MS4 is delineated
sewersheds (drainage area served by a sewer system), most jurisdictions could provide only
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municipal boundaries as an estimated MS4 area. There might be additional developed land,
however, outside the municipal boundaries that also drains to the MS4 area that can be shown by
GIS data. The Phase 5.3 Bay Watershed Model uses the GIS data and topographic information to
delineate the sewershed, which includes all land in the municipal boundaries and developed land
outside the municipal boundaries that drains to the MS4 (USEPA 2010J).
Septic Loads
Septic system loads are calculated on the basis of U.S. Census Bureau estimates of the number of
systems in the watershed and standard assumptions regarding nitrogen waste generation and
attenuation. The model simulates nitrate discharges directly to stream and river reaches (USEPA
2010J).
5.8.4 Calibration
The Phase 5.3 Bay Watershed Model segments are defined such that segment outlets are in
proximity to in-stream flow gauging and water quality monitoring stations to increase the
accuracy of model calibration. Calibration involved comparing available streamflow and water
quality data for the years 1985 to 2005 to watershed model calibration output for the same
period.
To calibrate the model output, various water quality parameters such as simulated streamflows,
TSS (sediment), total phosphorus, organic phosphorus, particulate phosphorus, phosphate, total
nitrogen, nitrate, total ammonia, and organic nitrogen concentrations and loads, temperature, and
DO were compared to the observed data from the in-stream monitoring sites (Figure 5-15).
Through the application of an automated calibration process, model parameters were adjusted to
optimize the representation of observed in-stream conditions (USEPA 2010J).
The calibrated Bay Watershed Model was run for a 21-year hydrologic period (1985-2005) to
simulate loads for various evaluation scenarios. Those loads were linked to the Bay Water
Quality Model to test whether a given scenario met the Bay jurisdictions' WQS in the Bay.
Modeled loads are reported as the average annual load over the modeled period.
5.9 CHESAPEAKE BAY WATER QUALITY AND SEDIMENT
TRANSPORT MODEL
The Bay Watershed Model was linked to the Chesapeake Bay Water Quality and Sediment
Transport Model (Bay Water Quality Model), which in turn was used to evaluate the impacts on
Bay water quality conditions in response to changes in nitrogen, phosphorus, and sediment
loading levels.
The Bay Water Quality Model combines a three-dimensional hydrologic transport model
(CH3D) with a eutrophication model (CE-QUAL-ICM) to predict water quality conditions in the
Bay resulting from changes in loads from the contributing area (Figure 5-16). The hydrodynamic
model computes intra-tidal transport using a three-dimensional grid framework of 57,000 cells
(Cerco et al. 2010). The sediment transport model computes continuous three-dimensional
velocities, surface elevation, vertical viscosity and diffusivity, temperature, salinity, and density
using time increments of 5 minutes.
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Chesapeake Bay TMDL
Hydrology Calibration Stations
• Flow
WSM Phase 5 River Segments
-A.
0 30 <0 120 M4«
Water Quality Calibration Stations
o Phosphorus
• Nitrogen
WSM Phase 5 River Segments
0 30 60 I20M1M
0
CD O
Source: USEPA 201 Oj
Figure 5-15. Phase 5.3 Chesapeake Bay Watershed Model hydrology (upper panel) and water quality (lower
panel) monitoring calibration stations overlaid on the Phase 5.3 Bay Watershed Model's river segments.
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Chesapeake Bay TMDL
Richmond
Salisbury
0 5 10 J31M..
Source: Cercoetal. 2010
Figure 5-16. The detailed 57,000 cell grid of the Chesapeake Bay Water Quality and Sediment Transport
Model.
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Chesapeake Bay TMDL
The hydrodynamic model was calibrated for the period 1991-2000 and verified against the large
amount of observed tidal elevations, currents, and densities available for the Bay.
Computed flows, surface elevations, and vertical diffusivities from the hydrodynamic model
were output at 2-hour intervals for use in the water quality model. Boundary conditions were
specified at all river inflows, lateral flows, and at the mouth of the Bay.
The eutrophication (water quality) model computes algal biomass, nutrient cycling, and DO, as
well as numerous additional constituents and processes using a 15-minute time step (Cerco and
Cole 1993; Cerco 2000; Cerco et al. 2002; Cerco and Noel 2004). In addition, the eutrophication
model incorporates a predictive sediment diagenesis8 component, which simulates the chemical
and biological processes undergone at the sediment-water interface after sediment are deposited
(Di Toro 2001; Cerco and Cole 1994).
Loads to the system include distributed or nonpoint source loads, point source loads, atmospheric
loads, bank loads, and wetlands loads. Nonpoint source loads enter the tidal system at tributary
fall lines and as runoff below the fall lines. Point source loads are from industries and municipal
wastewater treatment plants. Atmospheric loads are deposited directly to the Bay tidal surface
waters. Atmospheric loads to the watershed are incorporated in the distributed loads. Bank loads
originate with shoreline erosion. Wetland loads are materials created in and exported from
wetlands and include exported wetland oxygen demand.
Detailed documentation on the Chesapeake Bay Water Quality and Sediment Transport Model
(Cerco and Noel 2004; Cerco et al. 2010) is at
http://ww\v.chesapeakeba\.net/content/publicationsA:bp 26167.pdf.
5.9.1 Nonpoint Source Loads
Nonpoint source loads to the Bay Water Quality Model are from the Phase 5.3 Bay Watershed
Model. Loads are provided daily, routed to surface cells on the model grid. Routing is based on
local watershed characteristics and on drainage area contributing to the cell adjacent to the land
(USEPA2010J).
5.9.2 Point Source Loads
Wastewater discharged loads to the Bay Water Quality Model were based on reports provided by
state and local agencies which, depending on the source, were specified annually or monthly. In
the model, loads from individual sources were summed into loads to model surface cells and
were provided monthly (USEPA 2010J).
5.9.3 Atmospheric Loads
The EPA CBP Office computed the daily atmospheric loads to each Water Quality Model
surface cell (USEPA 201 Oj). Wet deposition loads of ammonium and nitrate were derived from
National Atmospheric Deposition Program observations. Dry deposition load was derived from
8 Predictive sediment diagenesis is a predictive model of how organic material and nutrients in sediment on the Bay
floor are processed.
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Chesapeake Bay TMDL
the CMAQ. Deposition loads of organic and inorganic phosphorus were specified on a uniform,
constant, areal basis derived from published values.
5.9.4 Bank Loads
Bank loads are the solids, carbon, nitrogen, and phosphorus loads contributed to the water
column through shoreline erosion. Although erosion is episodic, bank loads can be estimated
only as long-term averages by areal surveys. The volume of eroded material is commonly
quantified from comparison of topographic maps or aerial photos separated by time scales of
years. Consequently, the erosion estimates are averaged over periods of years, but bank loads are
input into the Bay Water Quality Model as episodic events as determined by a wave energy
submodel. Bank loads were estimated for shoreline and sub-tidal erosion for much of the
Chesapeake Bay shoreline on a scale of about every 10 kilometers of shoreline.
5.9.5 Wetlands
Wetlands loads are the sources (or sinks) of oxygen and oxygen-demanding material, such as
carbon, that is associated with wetlands that fringe the shore of the Bay and tributaries. These
loads are invoked primarily as an aid in calibrating tidal tributary dissolved oxygen
concentrations. Loads to each cell were computed by multiplying the amount of adjacent
wetlands area by the amount of areal carbon export or oxygen consumption. A uniform carbon
export of 0.3 grams carbon per meters2 per day was employed, leading to a uniform oxygen
demand of 2 gram oxygen per meters2 per day. Segments receiving the largest carbon loads and
subject to the greatest oxygen consumption include the mid-portion of the Bay, Tangier Sound,
several Eastern Shore tidal tributaries, the tidal middle and lower James River, the tidal fresh
York River, and the tidal York River mouth.
5.9.6 Model Setup
Within the Bay Water Quality Model, 90 of the 92 Chesapeake Bay segments are fully
represented within the 57,000 model cells and fully simulated. Two Bay segments—the Western
Branch Patuxent River and the Chesapeake and Delaware Canal—were either not included in the
modeled Chesapeake Bay segments or not fully simulated in the Chesapeake Bay Water Quality
and Sediment Transport Model. Bay TMDLs were developed for both of these Bay segments
using information from the Phase 5.3 Bay Watershed Model, Bay Water Quality Model results
from adjoining tidal Bay segments, and other documented sources (see Section 9).
The Western Branch Patuxent River (WBRTF) segment in Maryland (see Table 2-1 and Figure
2-5) was not simulated in the Bay Water Quality Model because of the lack of quality data on the
tidal river's bathymetry (Cerco et al. 2010). In June 2000, the Maryland Department of
Environment published a BOD TMDL for this tidal river segment to address DO impairments
(MDE 2000). Therefore, WBRTF is listed on Category 4a for a BOD TMDL on Maryland's
2008 Integrated Report (see Table 2-1) (MDE 2008). A TMDL for segment WBRTF has been
developed on the basis of: (1) Maryland Department of Environment's original BOD TMDL and
loading information from the surrounding Phase 5.3 watershed model segments that drain
directly into the Western Branch Patuxent River segment; and (2) outputs from the down-tide
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Patuxent River segments (PAXTF, PAXOH, PAXMH), which are also listed as impaired (see
Table 2-1 and Section 9) (MDE 2008).
The Delaware portion of the Chesapeake and Delaware Canal (C&DOH DE) is simulated in the
Bay Water Quality Model as a boundary condition for the Delaware Bay using constant flow
and load (Cerco et al. 2010). The segment is listed as impaired (see Table 2-1) (DE DNREC
2008). A Chesapeake Bay TMDL for segment C&DOH_DE was developed using a combination
of loading information from the surrounding Phase 5.3 Bay Watershed Model segments that
drain directly into this Bay segment and outputs from the down-tide Chesapeake Bay segments
(C&DOH MD, ELKOll, and CB1TF), which also are listed as impaired (see Table 2-1 and
Section 9) (MDE 2008).
5.10 CHESAPEAKE BAY CRITERIA ASSESSMENT PROGRAM
Output from the Bay Water Quality Model is used to modify historical water quality monitoring
observations from the period 1991-2000 for the purposes of determining Chesapeake Bay WQS
attainment under various pollutant load reduction scenarios (for more details on this process, see
Section 6.2.2). To perform the necessary procedures on the large amount of data required from
both the Bay Water Quality Model and the Chesapeake Bay Water Quality Monitoring Program
database, a set of FORTRAN modules was developed. These post-processing modules read
output from the Bay Water Quality Model (hourly values for DO; daily values for chlorophyll a),
perform regression analyses, and apply those regressions to the appropriate historical monitoring
data set. Additional FORTRAN modules then perform the same standardized, automated criteria
assessment procedures that are used to assess more recent monitoring data for the Bay
jurisdictions' section 303(d) listing reports.
The source code for this suite of FORTRAN modules is maintained by the EPA CBP Office's
Modeling and Monitoring teams on behalf of the partnership and is accessible at
ftp://ftp.chesapeakebav.net/Monitoring/CrileriaAssessment/.
The process by which historical monitoring data are scenario-modified using output from the
Bay Water Quality Model is summarized in Section 6.2.2. For a detailed description of the
Chesapeake Bay water quality criteria assessment procedures used for generating 303(d) listings,
see EPA's Ambient Water Quality Criteria for Dissolved Oxygen, Water Clarity and Chlorophyll
a for the Chesapeake Bay and Its Tidal Trihutaries-2008 Technical Support for Criteria
Assessment Protocols Addendum (USEPA 2008a) and EPA's Ambient Water Quality Criteria for
Dissolved Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and Its Tidal
Tributaries: 2010 Technical Support for Criteria Assessment Protocols Addendum (USEPA
2010a).
5.11 CLIMATE CHANGE SIMULATION
The potential effects of future climate change were accounted for in the current Bay TMDL
allocations based on a preliminary assessment of climate change impacts on the Chesapeake Bay.
9 Boundary conditions refer to the definition or statement of conditions or phenomena at the boundaries of a model;
water levels, flows, and concentrations that are specified at the boundaries of the area being modeled.
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Chesapeake Bay TMDL
Because of well known limitations in the current suite of Bay models to fully simulate the effects
of climate change as listed below, EPA and its partners are committed to a more comprehensive
assessment in 2017. Effects of climate change already observed in the mid-Atlantic region have
been factored in the Bay TMDL through the application of recent records of precipitation,
streamflow, and Chesapeake Bay water column temperatures which reflect changes in the
regional climate over the past several decades.
A preliminary assessment of climate change impacts on the Chesapeake Bay was conducted, in
parallel, using an earlier version of the Phase 5 Bay Watershed Model and tools developed for
EPA's BASINS 4 system including the Climate Assessment Tool (see Appendix E for details).
Flows and associated nutrient and sediment loads were assessed in all river basins of the
Chesapeake Bay with three key climate change scenarios reflecting the range of potential
changes in temperature and precipitation in the year 2030. The three key scenarios came from a
larger set of 42 climate change scenarios that were evaluated from seven Global Climate Models,
two scenarios from the Intergovernmental Panel on Climate Change Special Report on Emissions
Scenarios storylines, and three assumptions about precipitation intensity in the largest events.
The 42 climate change scenarios were run on the Phase 5 Watershed Model of the Monocacy
River watershed, a subbasin of the Potomac River basin in the Piedmont region, using a 2030
estimated land use based on a sophisticated land use model containing socioeconomic estimates
of development throughout the watershed.
The results provide an indication of likely precipitation and flow patterns under future potential
climate conditions (Linker et al. 2007, 2008) (see Appendix E). Projected temperature increases
tend to increase evapotranspiration in the Bay watershed, effectively offsetting increases in
precipitation. The preliminary analysis indicated overall decreases in annual stream flow,
nitrogen and phosphorus loads. The higher intensity precipitation events yielded estimated
increases in annual sediment loads. These preliminary findings support the nitrogen and
phosphorus allocations within the Bay TMDL and application of an implicit margin of safety for
these two pollutants, recognizing these loads might not increase, even decrease. These same
preliminary findings support EPA's decision for an explicit sediment allocation margin of safety,
recognizing the potential for increased sediment loads.
EPA and its partners are committed to conducting a more complete analysis of climate change
effects on TMDL nitrogen, phosphorus, and sediment loads, which is to be made during the mid-
course assessment of Chesapeake Bay TMDL progress in 2017 as called for in Section 203 of the
Chesapeake Executive Order 13508 (May 12,2009) (please see Section 10.5 for more details).
To carry out a more complete analysis of climate change effects, changes will be needed to the
current suite of Bay models and tools including:
• Applying the results from the next generation of global climate change models to develop
the best available estimates of the effects of climate change on the mid-Atlantic region
• Developing a better means for down-scaling the results from the applicable global climate
change models to match the finer segmentation of the Phase 5.3 Chesapeake Bay
Watershed Model
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Chesapeake BayTMDL
• Developing the means to better understand and fully simulate the interactions between
increased evapotranspiration and high intensity precipitation events within the Chesapeake
Bay Watershed Model
• Building the capacity to simulate the effects of change in tidal water column temperatures
on all the existing temperature dependent rates and processes currently simulated with the
hydrodynamic, estuarine water quality, sediment transport, living resources and filter
feeder component models of the Chesapeake Bay Water Quality and Sediment Transport
Model
• Reevaluate the temperature dependent effects on key species and communities (e.g.,
eelgrass) to ensure the latest scientific understanding has been factored into the suite of Bay
models
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SECTION 6. ESTABLISHING THE ALLOCATIONS FOR
THE BASIN-JURISDICTIONS
The process that informed EPA's decisions establishing the Chesapeake Bay TMDL involved
many stakeholders, most notably, the Bay jurisdiction partners. A four-step process was used for
the development of the TMDL. Those steps were
1. EPA defined 19 major river basin and jurisdictional loading allocations—July 1. 2010,
for nitrogen and phosphorus; August 13, 2010, for sediment. The methodology that EPA
used in defining those allocations is described in detail in this section.
2. Each jurisdiction developed a Phase I Watershed Implementation Plan (WIP) that
described how it would achieve the target allocations for nitrogen, phosphorus, and
sediment assigned to the jurisdictions and basins in step 1.
3. EPA evaluated the jurisdictions' suballocations and final Phase 1 WIPs to determine
whether they met the jurisdiction-wide and major river basin allocations, included
adequate detail to ensure that NPDES permits arc consistent with the assumptions and
requirements of the WLAs, and provided sufficient reasonable assurance that nonpoint
source reductions could be achieved and maintained through credible and enforceable or
otherwise binding strategies in jurisdictions that are signatories to the Chesapeake Bay
Agreement, and similarly effective strategies in non-signatory jurisdictions. That
evaluation and its results are described in detail in Section 8.
On the basis of the results of its evaluation, EPA established an allocation scenario for the final
Chesapeake Bay TMDL, including allocations for each of the 92 Bay segments, using
suballocations provided in the final Phase 1 WIPs, alternative EPA backstop allocations, or a
combination of the two. Tables showing the 92 Bay segment-specific and sector-specific
allocations of the Chesapeake Bay TMDL are in Section 9.
This section describes the method used to derive the basin-jurisdiction allocations described in
Step 1 above. The following subsections discuss the specific approaches adopted to address
specific technical aspects of the Chesapeake Bay TMDL:
• 6.1 -Establishing the overall model parameters
• 6.2-Establishing the nitrogen and phosphorus model parameters
• 6.3-Methodology for establishing the basin-jurisdiction allocations for nitrogen and
phosphorus
• 6.4-Establishing the Basin-jurisdiction allocations for nitrogen and phosphorus
• 6.5-Establishing the sediment model parameters
• 6.6-Establishing the basin-jurisdiction allocations for sediment
• 6.7-Basin-jurisdiction allocations to achieve the Bay WQS
• 6.8-Attainment of the District of Columbia pH WQS
The Chesapeake Bay Program partners initiated discussions related to the technical aspects of the
Chesapeake Bay TMDL starting at the September 2005 Reevaluation Workshop sponsored by
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Chesapeake Bay TMDL
what would become the partnership's Water Quality Steering Committee (Chesapeake Bay
Reevaluation Steering Committee 2005). Over the next 5 years, EPA and its partners, in
particular members of the Water Quality Steering Committee (2005-2008) and then the Water
Quality Goal Implementation Team (WQGIT) (2009 present) systematically evaluated and
agreed on approaches to address multiple technical aspects related to developing the Bay TMDL.
EPA, together with its seven watershed jurisdictional partners, developed and applied approaches
and methodologies to address a number of factors in developing the Bay TMDL. A multitude of
policy, programmatic, and technical issues were addressed through this collaborative process.
6.1 Establishing the Overall Model Parameters
The first step in the process was to establish the key parameters for the models used in
developing the TMDL. The model parameters discussed below are those that are common to
developing TMDLs that ensure attainment for all three water quality criteria: DO, chlorophyll a
and submerged aquatic vegetation (SAV)Avater clarity. Those key parameters are: (I) the
hydrologic period, or the period that is representative of typical conditions for the waterbody; (2)
the seasonal variation in water quality conditions and the factors (e.g., temperature, precipitation
and wind) that directly affect those conditions; and (3) the development of daily loads for the
TMDL.
6.1.1 Hydrologic Period
The hydrologic period for modeling purposes is the period that represents the long-term
hydrologic conditions for the waterbody. This is important so that the Bay models can simulate
local long-term conditions for each area of the Bay watershed and the Bay's tidal waters so that
no one area is modeled with a particularly high or low loading, an unrepresentative mix of point
and nonpoint sources or extremely high or low river flow. The selection of a representative
hydrologic averaging period ensures that the balance between high and low river flows and the
resultant point and nonpoint source loadings across the Bay watershed and Bay tidal waters are
appropriate. The hydrologic period also provides the temporal boundaries on the model scenario
runs from which the critical period is determined (see Section 6.2.1).
To identify the appropriate hydrologic period, EPA analyzed decades of historical stream flow
data. It is important when determining representative hydrology to be able to compare various
management scenarios through the suite of Bay models. In the course of evaluating options for
the TMDL, EPA and its jurisdictional partners ran numerous modeling scenarios through the Bay
Watershed and the Bay Water Quality Sediment Transport models with varying levels of
management actions (e.g., land use, BMPs, wastewater treatment technologies) held constant
against an actual record of rainfall and meteorology to examine how those management actions
perform over a realistic distribution of simulated meteorological conditions.
Because of the long history of monitoring throughout the Chesapeake Bay watershed, the CBP
partners were in the position of selecting a period for model application representative of typical
hydrologic conditions of the 21 contiguous model simulation years—1985 to 2005. Two extreme
conditions occurred during the 21-year model simulation period for the Chesapeake Bay models:
Tropical Storm Juan in November 1985, and the Susquehanna Big Melt of January 1996. In the
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Chesapeake Bay TMDL
Chesapeake Bay region. Tropical Storm Juan was a 100-year storm primarily affecting the
Potomac and James River basins. No significant effect on SAV or DO conditions was reported in
the aftermath of Tropical Storm Juan. In the case of the Susquehanna Big Melt in January 1996.
a warm front brought rain to the winter snow pack in the Susquehanna River basin and caused an
ice dam to form in the lower reaches of the river. No significant effects on SAV or DO were
reported from that 1996 extreme event, likely because of the time of year when it occurred (late
winter).
From the 21-year period, EPA selected a contiguous 10-year hydrologic period because a
10-year period provides enough contrast in different hydrologic regimes to better examine and
understand water quality response to management actions over a wide range of wet and dry
years. Further, a 10-year period is long enough to be representative of the long-term flow
(Appendix F). Finally, a 10-year period is within today's capability of computational resources.
particularly for the Chesapeake Bay Water Quality Sediment Transport Model (Bay Water
Quality Model), which required high levels of parallel processing for each management scenario.
The annuali/.ed Bay TMDL allocations are expressed as an average annual load over the 10-year
hydrologic period.
EPA then determined which 10-year period to use by examining the statistics of long-term flow
relative to each 10-year period at nine USGS gauging stations measuring the discharge of the
major rivers flowing to the Bay (Appendix F). All the contiguous 10-year hydrologic periods
from 1985 to 2005 appeared to be suitable because quantifiable assessments showed that all the
contiguous 10-year periods had relatively similar distributions of river flow.
EPA selected the 10-year hydrologic assessment period from 1991 to 2000 from the 21-year flow
record for the following reasons:
• It is one of the 10-year periods that is closest to an integrated metric of long-term flow.
• Each basin has statistics for this period that were particularly representative of the long-term
flow.
• It overlaps several years with the previous 2003 tributary strategy allocation assessment
period (1985-1994), which facilitated comparisons between the two assessments.
• It incorporates more recent years than the previous 2003 tributary strategy allocation
assessment period (1985-1994).
• It overlaps with the Bay Water Quality Transport Model calibration period (1993-2000).
which is important for the accuracy of the model predictions.
• It encompasses the 3-year critical period (1993-1995) for the Chesapeake Bay TMDL as
explained in Section 6.2.1 below.
More detailed documentation on the determination of the hydrologic period is provided in
Appendix F.
6.12 Seasonal Variation
A TMDL analysis must consider the seasonal variations within the watershed (CWA
303(d)(l)(C); 40 CFR 130.7). The Chesapeake Bay TMDL inherently considers all seasons
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Chesapeake Bay TMDL
through the use of a continuous 10-year simulation period that captures seasonal precipitation on
a year-to-year basis throughout the entire watershed. Furthermore, the critical periods selected
for this TMDL, being a minimum of 3 consecutive years provide further assurance that the
seasonality of the Bay loading and other dynamics are properly addressed in this TMDL. In this
way, the TMDL simulations ensure attainment of WQS during all seasons.
Seasonal Variation in the Jurisdictions' Bay Water Quality Standards
In the case of the Chesapeake Bay TMDL, the Chesapeake Bay WQS adopted by the four tidal
Bay jurisdictions are biologically based and designed to be protective of Chesapeake living
resources, including full consideration of their unique seasonal-based conditions (see Section 3)
(USEPA 2003a, 2003c). To assess the degree of WQS achievement using the Bay Water Quality
Model, an overlay of the time and space dimensions are simulated to develop an assessment that
is protective of living resources with consideration of all critical periods within the applicable
seasonal period (USEPA 2007a).
The same approach of considering the time and space of the critical conditions is applied in the
assessment of the WQS achievement with observed monitoring data. Ultimately, the time and
space of water quality exceedances are assessed against a reference curve derived from healthy
living resource communities to determine the degree of WQS achievement (USEPA 2007a).
Model Simulation Supporting Seasonal Variation
The suite of Chesapeake Bay Program models being used to establish the Chesapeake Bay
TMDL—Bay Airshed, Bay Watershed, Bay Water Quality, Bay Sediment Transport, Bay filter
feeders—all simulate the 10-year period and account for all storm events, high flows/low flows,
and resultant nitrogen, phosphorus, and sediment loads across all four seasons. The full suite of
Chesapeake Bay models operate on at least an hourly time-step and often at finer time-steps for
the Bay Airshed Model and the Bay Water Quality Model (see Sections 5.4 and 5.9,
respectively). Therefore, through proper operation of the suite of Bay models, the Chesapeake
Bay TMDL considers all seasons and within season variations through the use of a continuous
10-year simulation period (see Section 6.1.1).
Seasonal Variations Known and Addressed through Annual Loads
A key aspect of Chesapeake Bay nitrogen and phosphorus dynamics is that annual loads are the
most important determinant of Chesapeake Bay water quality response (USEPA 2004c).
Chesapeake Bay physical and biological processes can be viewed as integrating variations in
nitrogen, phosphorus, and sediment loads over time. The integration of nitrogen, phosphorus,
and sediment loads over time allows for an analysis of loads in the Chesapeake Bay that is
minimally influenced by short-term temporal fluctuations. Bay water quality responds to overall
loads on a seasonal to annual scale, while showing little response to daily or monthly variations
within an annual load.
Numerous Chesapeake Bay studies show that annually based wastewater treatment of nitrogen
and phosphorus reductions are sufficient to protect Chesapeake Bay water quality (Linker 2003,
2005). The seasonal aspects of the jurisdictions' Chesapeake Bay WQS are due to the presence
and special seasonal needs of the living resources being protected (e.g., spawning), but annual
nitrogen, phosphorus, and sediment load reductions are most important to achieve and maintain
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the seasonal water quality criteria, some of which protect multiple season designated uses—
open-water, shallow-water bay grass, and migratory spawning and nursery (USEPA 2003a,
2003d).
6.1.3 Daily Loads
Consistent with the D.C. Circuit Court of Appeals decision in Friends of the Earth. Inc. v. EPA.
in addition to the annual loading expressions of the pollutants in this TMDL, EPA is also
expressing its Chesapeake Bay TMDL in terms of daily time increments (446 F.3d 140 [D.C.
Cir. 2006]). Specifically, the Chesapeake Bay TMDL has developed a maximum daily load
based on annual and seasonal loads for nitrogen, phosphorus, and sediment for each of the 92
Chesapeake Bay segments. EPA also recognizes that it may be appropriate and necessary to
identify non-daily allocations in TMDL development despite the need to also identify daily
loads. In an effort to fully understand the physical and chemical dynamics of a waterbody,
TMDLs can be developed using methodologies that result in the development of pollutant
allocations expressed in monthly, seasonal, or annual periods consistent with the applicable
WQS. TMDLs can be developed applying accepted and reasonable methodologies to calculate
the most appropriate averaging period for allocations on the basis of factors such as available
data, watershed and waterbody characteristics, pollutant loading considerations, applicable
WQS, and the TMDL development methodology. Consistent with that policy, the Chesapeake
Bay TMDL was developed and is expressed in annual loads. In addition. EPA calculated daily
loads to reflect a statistical expression of an annually-based maximum daily load and a
seasonally-based maximum daily load. Appendix R of this TMDL includes detailed nitrogen,
phosphorus, and sediment annually based maximum daily allocations to achieve applicable
WQS. The spreadsheet lists total nitrogen, phosphorus, and sediment loads as delivered to the
Chesapeake Bay's tidal waters. Daily load allocations are shown for each of the 92 segments and
by sources for WLAs including agriculture (CAFOs), stormwater (MS4s), vvastevvater (CSO) and
wastewater (significant and nonsignificant by NPDES permit); and for LAs including
agriculture, forest, nontidal atmospheric deposition, onsite treatment systems, and urban sources.
Approach for Expressing the Maximum Daily Loads
The methodology applied to calculate the expression of the maximum daily loads and associated
vvasteload and load allocations in the Chesapeake Bay TMDL is consistent with the approach
contained in EPA's published guidance, Establishing TMDL "Daily' Loads in Light of the
Decision hv the U.S. Court of Appeals for the D.C. Circuit in Friends of the Earth, Inc. v. EPA.
etai, No. 05-5015. (April 25. 2006) and Implications for NPDES Permits, dated November 15.
2006 (USEPA 2006). Additionally, the analytical approach selected in the Bay TMDL is similar
to the wide range of technically sound approaches and the guiding principles and assumption
described in the technical document Options for the Expression of Daily Loads in TMDLs
(USEPA 2007c).
Computing the Daily Maximum Loads and the Seasonal Daily Maximum Loads
Annually based maximum daily loads are derived for each of the 92 tidal segments and for each
of the three pollutants—nitrogen, phosphorus, and sediment—as a direct product of the
Chesapeake Bay TMDL and associated modeling. That modeling output serves as the starting
point for the annually-based maximum daily load expression and the seasonally-based maximum
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Chesapeake Bay TMDL
daily load expression. Those daily maximum loads are a function of the 10-year continuous
simulation produced by the paired Bay Watershed-Bay Water Quality models. The modeling
approach allows for the daily maximum load expression to be taken directly from the output of
the TMDL itself, assuring a degree of consistency between the daily maximum load calculation
and the annual loads necessary to meet applicable WQS included in the final TMDL. That is, the
methodology uses the annual allocations derived through the modeling/TMDL analysis, and
converts those annual loads to daily maximum loadings.
Both the Chesapeake Bay TMDL annually-based maximum daily load and seasonally based
maximum daily load represents the 95th percentile of the distribution to protect against the
presence of anomalous outliers. That expression implies a 5 percent probability that an annually-
based daily or seasonal-based daily maximum load will exceed the specified value under the
TMDL condition. However, during such unlikely events, compliance with the annual loading
will assure that applicable WQS will be achieved.
On the basis of probability analysis, a loading that will be achieved 100 percent of the time
cannot be calculated. So some percentage probability of attainment must be chosen that is less
than 100 percent but high enough that there is comfort that the loading will be achieved. A 95
percent probability is often determined by EPA to be appropriate in environmental matters (like
WQS and NPDES permitting) and has also been chosen in this application. The EPA guidance
mentioned above provides for much discretion in selecting the percent probability to use in the
daily calculation. Because the calculation is for a daily maximum value, it is EPA's professional
opinion that, with regard to the Chesapeake Bay TMDL, a 95 percent probability is most
appropriate. The steps employed to compute the annually or seasonally based maximum daily
load for each segment were as follows:
1. Calculate the annual average loading for each of the 92 Bay segments; that would be the
annual loading under the TMDL/allocation condition. Annual allocations are in Section 9
and Appendix Q.
2. Calculate the 95th percentile of the daily loads delivered to each of the 92 Bay segments
(using the same loading condition as step 1).
3. Calculate the Annual/Daily Maximum ratio (ADM) for each of the 92 Bay segments by
dividing the annual average load by the 95th percentile calculated in Step 2.
4. Calculate a Baywide ADM by computing a load-weighted average of all 92 Bay
segments ADM ratios. Table 6-1 provides the annual Baywide ADM.
5. Divide all the annual TMDLs, WLAs, and LAs in each of the 92 Bay segments in the
TMDL by the Baywide ADM. Those are the calculated annual-based daily maximum
loads found in Appendix R.
6. Using the approach described in steps 1-5 above, calculate a Baywide ADM for each
season for each of the 92 Bay segments. Table 6-1 provides the Seasonal Baywide ADM.
7. Divide all the annual TMDLs in each of the 92 tidal segments in the TMDL by Seasonal
ADM to calculate the seasonally-based maximum daily load.
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Table 6-1. ADM for calculating daily maximum loads
Total Nitrogen
Total Phosphorus
Total Suspended Solids
Winter
123.7
95.8
96.5
Spring
80.9
60.1
58.0
Summer
337.1
260.7
384.7
Fall
210.9
141.2
158.1
All year
123.6
98.2
100.3
It should be noted that a statistical expression of a daily load is just that, an expression of the
probability that a specific maximum daily load will occur in a given segment for a specific
pollutant. The magnitude of the TMDL allocations was established to assure the attainment of all
applicable WQS in each of the 92 tidal Bay segments. EPA has provided annually based
maximum daily load expressions in Appendix R. Seasonally based maximum daily loads can be
calculated by dividing the annual allocations by the seasonal ADMs in Table 6-1. That seasonal
expression reflects a temporally variable target because the various pollutant sources (point and
nonpoint) vary significantly by month and by season. The annually based daily maximum loads
represent the infrequent, maximum inputs into the Chesapeake Bay. The annually based
maximum daily load and the seasonally based maximum daily load provide a range of conditions
that are acceptable on a daily basis and that will meet overall TMDL allocations and the
applicable WQS.
The Expression of Daily Loads and NPDES Permits
NPDES permit regulations require that effluent limits in permits be expressed as monthly
average and either weekly average or daily maximum, unless impracticable. As reflected in
EPA's March 3, 2004 Memorandum Annual Permit Limits for Nitrogen and Phosphorus for
Permits Designed to Protect Chesapeake Bay and its tidal tributaries from excess nitrogen and
phosphorus loadings under the National Pollutant Discharge Elimination System and EPA's
December 29, 2004 letters to each Chesapeake Bay watershed jurisdiction, which enclosed the
NPDES Permitting Approach for the Discharges of Nitrogen and Phosphorus in the Chesapeake
Bay Watershed'^ is EPA's best professional judgment that, when developing NPDES permit
limits consistent with this TMDL, jurisdictions should consider expressing permit effluent limits
for nitrogen and phosphorus as annual loads, instead of expressing the limits as monthly, weekly,
or daily limits (USEPA 2004c, 2004d). After consideration of complex modeling of the effect of
nitrogen and phosphorus loading to the Bay from individual point source discharges, EPA
concluded that the Chesapeake Bay and its tidal tributaries in effect integrate variable point
source monthly loads over time, so that as long as a particular annual total load of nitrogen and
phosphorus is met, constant or variable intra-annual load variation from individual point sources
has no effect on water quality of the main Bay. EPA recommends that because of the
characteristics of nitrogen and phosphorus loading and its effect on the water quality of the Bay,
the derivation of appropriate daily, weekly, or monthly permit limits is impracticable, and the
permit limits expressed in annual loads is appropriate. To protect local water quality, or for other
appropriate reasons, the NPDES permitting authority may also express the effluent limits in
monthly or daily terms.
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Chesapeake Bay TMDL
6.2 Establishing the Nitrogen and Phosphorus Related Model
Parameters
6.2.1 Critical Conditions
TMDLs are required to identify the loadings necessary to achieve applicable WQS. The
allowable loading is often dependent on key environmental factors, most notably wind, rainfall,
streamflow, temperature, and sunlight. Because those environmental factors can be highly
variable, EPA regulations require that in establishing the TMDL, the critical conditions (mostly
environmental conditions as listed above) be identified and employed as the design conditions of
the TMDL (40 CFR I30.7(c)(l)].
When TMDLs are developed using supporting watershed models, such as the Chesapeake Bay
TMDL, selecting a critical period for model simulation is essential for capturing important
ranges of loading/waterbody conditions and providing the necessary information for calculating
appropriate TMDL allocations that will meet applicable WQS. Because the WQS applicable to
this TMDL are assessed over 3-year periods, the critical period is defined as the 3-year period
within the previously selected 1991-2000 hydrologic period (see Section 6.1.1) that meets the
above description (USEPA 2003a). Critical conditions for sediment and SAV are discussed in
Section 6.5.1 below.
Critical Conditions for DO
In the Chesapeake Bay, EPA has found that as flow and nitrogen and phosphorus loads increase,
DO and water clarity levels decrease (Officer 1984). Therefore, EPA bases the critical period for
evaluation of the DO and water clarity WQS on identifying high-flow periods. Those periods
were identified using statistical analysis of flow data as described below and in detail in
Appendix G.
For the Bay TMDL, EPA conducted an extensive analysis of streamflow of the major tributaries
of the Chesapeake Bay as the primary parameter representing critical conditions. In that analysis,
it was observed that high streamflow most strongly correlated with the worst DO conditions in
the Bay. That is logical because most of the nitrogen and phosphorus loading contributing to low
DO in the Bay comes from nonpoint sources, whose source loads are driven by rainfall and
correlate well to rainfall and higher streamflows. Additionally, higher freshwater flows generally
increase water column stratification, preventing the low-DO bottom waters from being reaerated.
Because future rainfall conditions cannot be predicted, EPA analyzed rainfall from past decades
to derive a critical rainfall/stream flow condition that would be used to develop the allowable
loadings in the TMDL. The initial analysis concluded that the years 1996-1998 represented the
highest streamflow period for the Chesapeake Bay drainage during the 1991-2000 hydrology
period. However, it was later discovered that this 3-year period represented an extreme high-flow
condition that was inappropriate for the development of the TMDL—the high-flow period would
generally occur once every 20 years (Appendix G). After further analysis, EPA selected the
second highest flow period of 1993-1995 as the critical period. The 1993-1995 critical period
experienced streamflows that historically occurred about once every 10 years, which is much
more typical of the return frequency for hydrological conditions employed in developing TMDLs
(Appendix G). Thus, while the modeling for the Bay TMDL consists of the entire hydrologic
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Chesapeake Bay TMDL
period of 19Q1--2000. KPA used the water quality conditions during the 1993-1995 critical
period to determine attainment with the Bay jurisdictions' DO WQS.
Critical Conditions for Chlorophyll a
Algae, measured us chlorophyll a, responds to a multitude of different environmental factors.
parameters, and conditions including the following:
• Nitrogen and phosphorus loads
• Water column temperature
• pll conditions
• Local nitrogen and phosphorus conditions (e.g., fluxes of nitrogen and phosphorus from the
bottom sediment)
• River flow influences on dilution of existing algae populations
• River flow, bathymetry, and other factors influencing residence time
• Local weather conditions (e.g., wind, percentage of sunlight)
• Other conditions and parameters not well understood within the current state of the science
Some of those same factors influence DO conditions, while others are unique to algae. As
documented in Appendix G, using the same methodology as was used to determine the DO
critical period for the entire Chesapeake Bay, EPA conducted a flow analysis to support the
selection of a critical period for the tidal James River, which has numeric chlorophyll a criteria.
EPA based that analysis on the correlation between flow and violations of the numeric
chlorophyll a water quality criteria. The analysis showed no strong correlation between
streamflow and chlorophyll a conditions (Appendix G). As a result, EPA assessed numeric
chlorophyll a attainment using all eight of the 3-year criteria assessment periods (e.g., 1991-
1993, 1992-1994) that occur within the hydrologic period of 1991-2000.
6.2.2 Assessment Procedures for DO and Chlorophyll a Standards
The Bay Water Quality Model is used to predict water quality conditions for the various loading
scenarios explored. It is necessary to compare these model results with the applicable WQS to
determine compliance with the standards. This section describes the process by which model
results are compared to WQS to determine attainment.
In general, to determine management scenarios that achieved WQS, EPA ran model scenarios
representing different nitrogen, phosphorus, and sediment loading conditions using the Bay
Watershed Model. EPA then used the resultant model simulated nitrogen, phosphorus, and
sediment loadings as input into the Bay Water Quality Model to evaluate the response of critical
water quality parameters: specifically DO, SAV, water clarity, and chlorophyll a.
To determine whether the different loading scenarios met the Bay DO and chlorophyll « WQS,
EPA compared the Bay Water Quality Model's simulated tidal water quality response for each
variable to the corresponding observed monitoring values collected during the same 1991-2000
hydrological period. In other words, the Bay Water Quality Model was used primarily to
estimate the change in water quality that would result from various loading scenarios. The
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Chesapeake BayTMDL
model-simulated change in water quality is then applied to the actual observed calibration
monitoring data. In its simplest terms, the following steps were taken to apply the modeling
results to predict Bay DO and chlorophyll a WQS attainment:
I. Using the 1991 to 2000 hydrologic period, calibrate the Bay Water Quality Model to Bay
water quality monitoring data.
2. Run a model simulation for a given loading scenario (usually a management scenario
resulting in lower loads relative to the calibration scenario) through the Phase 5.3
Chesapeake Bay Watershed Model (Bay Watershed Model) and Bay Water Quality
Model.
3. Determine the model simulated change in water quality from the calibration scenario to
the given loading scenario.
4. Apply the change in water quality as predicted by the Bay Water Quality Model to the
actual historical water quality monitoring data used for calibration and evaluate
attainment on the basis of that scenario-modified data set.
5. If WQS are met, use the allocations for the TMDL. If WQS are not met, reduce and
readjust loads to meet WQS.
For a full discussion of the procedure, see Appendix H and the original report titled A
Comparison of Chesapeake Bay Estuary Model Calibration With 1985-1994 Observed Data and
Method of Application to Water Quality Criteria (Linker et al. 2002).
6.2.3 Addressing Reduced Sensitivity to Load Reductions at Low
Nonattainment Percentages
Mathematical models, including the models used in the Chesapeake Bay TMDL, are not perfect
representations of the real world. For that reason, it is important to use professional judgment in
the interpretation of those model results. One example of that is, for some segments, the Bay
Water Quality Model showed persistent nonattainment at consistently low levels even after the
loadings were lowered. After careful analysis, EPA concluded that the low (I percent) modeled
nonattainment levels were more an artifact of the modeling and assessment process, than a
representation of actual nonattainment. For that reason, EPA concluded that modeled
nonattainment of 1 percent or less was, in fact, attainment with the applicable WQS. The
subsection below describes the analysis that EPA conducted to arrive at this conclusion.
The Chesapeake Bay water quality criteria that the jurisdictions adopted into their respective
WQS regulations provide for allowable exceedances of each set of DO, water clarity, SAV, and
chlorophyll a criteria defined through application of a biological or default reference curve
(USEPA 2003a). Figure 6-1 depicts that concept in yellow as allowable exceedance of the
criterion concentration.
To compare model results with the WQS, EPA analyzes the Bay Water Quality Model results for
each scenario and for each modeled segment to determine the percent of time and space that the
modeled waster quality results exceed the allowable concentration. For any modeled result where
the exceedance in space and time (shown in Figure 6-1 as the area below the red line) exceeds
the allowable exceedance (shown in Figure 6-1 as the area below the blue line that is shaded
yellow), that segment is considered in nonattainment. The amount of nonattainment is shown in
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Chesapeake Bay TMDL
the figure as the area in white between the red line and the blue line and is displayed in model
results as percent of nonattainment for that segment. The amount of nonattainment is reported to
the whole number percent.
F
100
90
80
70
60
50
% 40
Q-
30
20
10
0
CFD Curve
Area of Criteria
Exceedence
Area of Allowable
Criteria
Exceedence
0 10 20 30 40 50 60 70 80 90 100
Percent of Space
Source USEPA 2003a
Figure 6-1. Graphic comparison of allowable exceedance compared to actual exceedance.
Dissolved Oxygen
Figure 6-2 displays Bay Water Quality Model results showing percent nonattainment of the 30-
day mean open-water DO criterion for various basinwide loading levels of the Maryland portion
of the lower central Chesapeake Bay segment CB5MH_MD.
As can be seen in Figure 6-2, there is a notable improvement in the percent nonattainment as the
loads are reduced until approximately I percent nonattainment. At a loading level of 191 million
pounds per year TN, the 1 percent nonattainment is persistent through consecutive reductions in
loading levels and remains consistent until a loading level of 170 million pounds per year TN is
reached. While this is one of the more extreme examples of persistent levels of I percent
nonattainment, this general observation of persistent nonattainment at 1 percent is fairly common
to the Bay Water Quality Model DO results (Appendix I).
Clear evidence of small, yet persistent percentage of model projected DO WQS nonattainment
over a wide range of reduced nitrogen and phosphorus loads across a wide range of segments and
designated uses, all of which are responding to nitrogen and phosphorus load reductions, is
documented in Appendix I. Because of those widespread observations, supported by independent
validation, and for purposes of developing the Chesapeake Bay TMDL, EPA determined that
nonattainment percentages projected by the Bay Water Quality Model rounded to 1 percent
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December 29, 2010
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Chesapeake Bay TMDL
would be considered in attainment for a segment's designated use. For a more detailed
discussion, see Appendix I.
CB5MH-MD Deep Water 1993-1995
10%
z
LU
Z
|
Z
LU
O
X
0
Q
LU
J
O
V)
5
9%
8%
7% •
6% I
5%
4%
l^^|
3%
2%
1%
0% '
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Chesapeake Bay TMDL
JMSMH Summer 1997-1999
Figure 6-3. Example of a James River segment's spring chlorophyll a WQS nonattainment results from a wide
range of TN loading Chesapeake Bay Water Quality Model scenarios.
6.2.4 Margin of Safety
Under EPA's regulations, a TMDL is mathematically expressed as
TMDL = £ WLA + VLA+ MOS
where
• TMDL is the total maximum daily load for the water segment
• WLA is the wasteload allocation, or the load allocated to point sources
• LA is the load allocation, or the load allocated to nonpoint sources
• MOS is the margin of safety to account for any uncertainties in the supporting data and the
model
The margin of safety (MOS) is the portion of the TMDL equation that accounts for any lack of
knowledge concerning the relationship between LAs and WLAs and water quality [CWA
303(d)(l)(c) and 40 CFR I30.7(c)(l)]. For example, knowledge is incomplete regarding the
exact nature and magnitude of pollutant loads from various sources and the specific impacts of
those pollutants on the chemical and biological quality of complex, natural waterbodies. The
MOS is intended to account for such uncertainties in a manner that is conservative from the
standpoint of environmental protection. On the basis of EPA guidance, the MOS can be achieved
through two approaches (USEPA 1999): (1) implicitly incorporate the MOS by using
conservative model assumptions to develop allocations; or (2) explicitly specify a portion of the
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December 29, 2010
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Chesapeake Bay TMDL
TMDL as the MOS and use the remainder for allocations. Fable 6-2 describes different
approaches that can be taken under the explicit and implicit MOS options.
Table 6-2. Different approaches available under the explicit and implicit MOS types
Type of MOS
Explicit
Implicit
Available approaches
Set numeric targets at more conservative levels than analytical results indicate.
Add a safety factor to pollutant loading estimates.
Do not allocate a portion of available loading capacity; reserve for MOS.
Use conservative assumptions in derivation of numeric targets.
Use conservative assumptions when developing numeric model applications.
Use conservative assumptions when analyzing prospective feasibility of practices
and restoration activities.
Source: USEPA 1999
Implicit Margin of Safety for Nitrogen and Phosphorus
The Chesapeake Bay TMDL analysis is built on a foundation of more than two decades of
modeling and assessment in the Chesapeake Bay and decades of Bay tidal waters and watershed
monitoring data. The Bay Airshed, Watershed, and Water Quality models are state-of-the-
science models, with several key models in their fourth or fifth generation of management
applications since the early and mid-1980s. The use of those sophisticated models to develop the
Bay TMDL, combined with application of specific conservative assumptions, significantly
increases EPA's confidence that the model's predictions of standards attainment are correct and,
thereby, supports the use of an implicit MOS for the Chesapeake TMDL.
The Chesapeake Bay TMDL for nitrogen and phosphorus applies an implicit MOS in derivation
of the DO and chlorophyll a-based nitrogen and phosphorus allocations through the use of
numerous conservative assumptions in the modeling framework. The principal set of
conservative assumptions used in the determining the actual allocations is as follows.
The basinwide allowable nitrogen and phosphorus loads were determined on the basis of
achieving a select set of deep-water and deep-channel DO standards in the mainstem Bay and
adjoining embayments—upper (CB3), middle (CB4MH) and lower (CB5MH) central
Chesapeake Bay, and lower Potomac River (POTMH MD). The Bay TMDL calls for nitrogen
load reductions upwards of 50 million pounds greater than that necessary to achieve the
applicable DO WQS in those four Bay segments compared with many of the remaining 88 Bay
segments.
The open-water and deep-water standards adopted by the jurisdictions have DO WQS that apply
to a 30-day mean and an instantaneous maximum. The open-water standards also have a 7-day
mean and the deep water use has a 1 -day mean. Last, the deep channel use has only a deep-
channel instantaneous minimum. The Bay TMDL assessed attainment of each of those standards.
But, as described in Appendix D and summarized in Section 3.3.3, the 30-day mean was clearly
the most restrictive of the standards for the open-water and deep-water use classifications. For
that reason, the allocations were based on 30-day mean for open-water and deep-water and
instantaneous standards for deep channel. Because the allocations to achieve those standards are
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Chesapeake Bay TMDL
significantly more restrictive than the allocations needed to achieve the other DO standards for
the Bay segments, there is an implicit MOS in achieving many of the Bay DO standards.
The DO standards apply year-round. Yet, at the allocated loadings, for the non-summer months
of the year, the standards will be readily achieved. Further, as described above, most of the Bay
and tributary tidal waters will readily achieve the applicable WQS at the allocated loads because
of the conservative assumption described above. So from an aggregate viewpoint, the expected
water quality at the allocated loads will readily attain the applicable WQS most of the time and
will marginally attain the applicable WQS only about once in 10 years, and only for a small
fraction of the summer months, and only for a very small portion of the volume of the Bay and
tidal tributary waters.
An assumption of the model is the concentration of nitrogen, phosphorus, and sediment from the
ocean waters entering the Bay. This is called a boundary condition. With improvement in
pollutant controls, it is expected that the coastal ocean concentration of the pollutants will go
down. EPA has conservatively estimated this reduction in coastal ocean water pollutant levels
but only for reductions in atmospheric deposition (see Appendix L). EPA has not adjusted this
boundary condition for expected land-based reductions. Such significant reductions can be
expected from Long Island Sound, Delaware River, and other mid-Atlantic estuaries that all
contribute nitrogen and phosphorus loads to Chesapeake Bay via the ocean boundary. Thus the
boundary condition in the model for the concentration and, therefore the loading, of nitrogen,
phosphorus, and sediment is higher than the concentration likely to exist with the application of
coastal, land-based controls.
In addition to the above, the extensive development and refinement of the Bay models provides
for excellent confidence in the modeling accuracy and conversely speaks to the need for a
minimal (implicit) MOS. The following are some, but not all, of the model attributes that are in
Section 5 that demonstrate the robust science behind the modeling network in support of the bay
TMDL:
• The models are based on decades of data (1985-2005) used to develop, calibrate, and
validate the models.
• A substantial increase in the number of stations was used to calibrate the watershed model
to available data.
• The models are in some cases in their fifth generation of refinement, because of extensive
input from baywide and national experts in the field.
• The modeling grid for both the Bay Watershed and Bay Water Quality and Sediment
Transport models has been refined up to ten times the previous number of modeling
segments.
The individual reasons cited above may not be sufficient to singly merit the conclusion that an
implicit MOS is appropriate for the nitrogen and phosphorus allocations, but together those
reasons provide ample support, in EPA's professional judgment, that an implicit MOS is
adequate.
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Chesapeake Bay TMDL
6.3 Methodology for Establishing the Basin-Jurisdiction Allocations
for Nitrogen and Phosphorus
An early step in the process of developing the Bay TMDL, especially for nitrogen and
phosphorus, is to determine the allowable loading from jurisdictions and major basins draining to
the Bay. As a result, an equitable approach must be employed to apportion the allowable loading
among the jurisdictions. This subsection describes the process EPA ultimately selected for this
Bay TMDL.
Nitrogen and phosphorus from sources further upstream within the Chesapeake Bay watershed
affect the condition of local receiving waters and affect tidal water quality conditions far
downstream, hundreds of miles away in some cases. For example, the middle part of the
mainstem Chesapeake Bay is affected by nitrogen and phosphorus from all parts of the Bay
watershed. A key objective of the nitrogen and phosphorus allocation methodology was to find a
process, based on an equitable distribution of loads for which the basinwide load for nitrogen and
phosphorus could be distributed among the basin-jurisdictions. This section describes the
specific processes involved in allocating the nitrogen and phosphorus loads necessary to meet the
jurisdictions' Chesapeake Bay DO and chlorophyll a WQS. While many alternative processes
were explored (Appendix K), only the process determined to be appropriate by EPA and agreed
upon by five of the seven Bay watershed jurisdictional partners are described here.
Principles and Guidelines
The nitrogen and phosphorus basin-jurisdiction allocation methodology was developed to be
consistent with the following guidelines adopted by the partnership:
• The allocated loads should protect the living resources of the Bay and its tidal tributaries
and result in all segments of the Bay mainstem, tidal tributaries, and embayments meeting
WQS for DO, chlorophyll «, and water clarity.
• Major river basins that contribute the most to the Bay water quality problems must do the
most to resolve those problems (on a pound-per-pound basis).
• All tracked and reported reductions in nitrogen and phosphorus loads are credited toward
achieving final assigned loads.
A number of critical concepts are important in understanding the major river basin by
jurisdiction nitrogen and phosphorus allocation methodology. They include the following:
• Accounting for the geographic and source loading influence of individual major river basins
on tidal water quality termed relative effectiveness
• Determining the controllable load
• Relating controllable load with relative effectiveness to determine the allocations of the
basinwide loads to the basin-jurisdictions
The following subsections further describe the above concepts and how they directly affect the
Chesapeake Bay TMDL.
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Chesapeake Bay TMDL
6.3.1 Accounting for Relative Effectiveness of the Major River Basins on
Tidal Water Quality
Relative effectiveness accounts for the role of geography on nitrogen and phosphorus load
changes and. in turn. Bay water quality. Because of various factors such as in-stream transport
and nitrogen and phosphorus cycling in the watershed, a given management measure on water
quality in the Bay, varies depending on the location of its implementation within the watershed
(USEPA 2003b). For example, the same control applied in Williamsport, Pennsylvania, will have
less of an effect on Bay DO than one applied in Baltimore, Maryland.
A relative effectiveness assessment evaluates the effects of both estuarine transport (location of
discharge/runoff loading to the Bay) and riverine transport (location of the discharge/runoff
loading in the watershed). EPA determined the relative effectiveness of each contributing river
basin in the overall Bay watershed on DO in several mainstem Bay segments and the lower
Potomac River by using the Bay Water Quality Model to run a series of isolation runs and using
the Bay Watershed Model to estimate attenuation of load through the watershed.
From the relative estuarine effectiveness analysis, several things are apparent. Northern, major
river basins have a greater relative influence than southern major river basins on the central Bay
and the lower Potomac River DO levels because of the general circulation patterns of the
Chesapeake Bay (up the Eastern Shore, down the Western Shore). Nitrogen and phosphorus
from the most southern river basins of the James and York rivers have relatively less influence
on mainstem Bay water quality because of their proximity to the mouth of the Bay. Because
these southern river basins are on the western shore, the counterclockwise circulation of the
lower Bay also tends to transport nitrogen and phosphorus loads from those larger southern river
basins out of the Bay mouth. That same counterclockwise circulation tends to sweep loads from
the lower Eastern Shore northward.
River basins whose loads discharge directly to the mainstem Bay, like the Susquehanna, tend to
have more effect on the mainstem Bay segments than basins with long riverine estuaries (e.g.,
the Patuxent, Potomac, and Rappahannock rivers). The long riverine estuaries, with longer water
residence times, allow nitrogen and phosphorus attenuation (burial and denitrification) before the
waters reaching the mainstem Chesapeake Bay. The size of a river basin is uncorrelated to its
relative influence, although larger river basins, with larger loads, have a greater absolute effect.
The upper tier of relative effect on the three mainstem segments includes the largest river basin
(Susquehanna) and the smallest (Eastern Shore Virginia). Their high degree of impact is because
they both discharge directly into the Bay, without intervening river estuaries to attenuate loads,
and they are both up-current relative to the general Bay circulation pattern.
The estuarine effectiveness is estimated by running a series of Bay Water Quality Model
scenarios holding one major river basin at E3 loads and all other major river basins at calibration
levels. After considering several metrics to assess the DO benefit from progressive reductions in
nitrogen and phosphorus loadings, EPA chose a 25th percentile. The advantage of this metric was
that it was based on DO values at the more critical lower end of the range (25th percentile) yet,
unlike a percent nonattainment metric, it could also be used for segments that were in attainment
under some loading scenarios. For each scenario, the increase in the 25th percentile DO
concentration during the summer criteria assessment period in the critical segments CB3MH,
CB4MH, and CB5MH for deep-channel and CB3MH, CB4MH, CB5MH, and POTMH for deep-
6-17 December 29, 2010
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Chesapeake Bay TMDL
water was recorded. The 25th percentile was selected as the appropriate metric as indicative of a
change in low DO. The riverine effectiveness is calculated as the fraction of load produced in the
watershed that is delivered to the estuary. It is estimated as an output of the watershed model.
For more details on this method, see Appendix K.
Absolute estuarine effectiveness accounts for the role of both total loads and geography on
pollutant load changes to the Bay. The absolute estuarine effectiveness of a contributing river
basin, measured separately both above and below the fall line, is the change in 25th percentile
DO concentration that results from a single basin changing from calibration conditions to E3. For
example, if the 25th percentile DO in the deep water of the lower Potomac River segment
POTMH moves from 5 to 5.3 mg/L from a change in loads from calibration to E3 in the Potomac
above fall line basin, the absolute estuarine effectiveness is 0.3 mg/L. Comparing the absolute
estuarine effectiveness among basins helps to identify which major river basins have the greatest
effect on WQS.
Relative estuarine effectiveness is defined as absolute estuarine effectiveness divided by the total
load reduction, delivered to tidal waters, necessary to gain that water quality response. For
example, if the load reduction in the Potomac above fall line basin was 30 million pounds of
pollutant to get a 0.3 mg/L change in DO concentration, the relative estuarine effectiveness is
0.01 mg/L per million pounds. The higher the relative estuarine effectiveness, the less reduction
required to achieve the change in status. The relative estuarine effectiveness calculation is an
attempt to isolate the effect of geography by normalizing the load on a per-pound basis.
Comparing the relative estuarine effectiveness among the major river basins shows the resulting
gain in attainment from performing equal pound reductions among the major river basins.
Riverine attenuation also has an effect on overall effectiveness. Loads are naturally attenuated or
reduced as they travel through long free-flowing river systems, making edge-of-stream loads in
headwater regions less effective on a pound-for-pound basis than edge-of-stream loads that take
place nearer tidal waters in the same river basin. The watershed model calculates delivery factors
as the fraction of edge-of-stream loads that are delivered to tidal waters. The units of riverine
attenuation are delivered pound per edge-of-stream pound.
Multiplying the estuarine relative effectiveness (measured as DO increase per delivered pound
reduction) by the riverine delivery factor (measured as delivered pound per edge-of-stream
pound) gives the overall relative effectiveness in DO concentration increase per edge-of-stream
pound. The relative estuarine effectiveness is the same for nitrogen or phosphorus, while the
riverine delivery is different, so the overall relative effectiveness is calculated separately for
nitrogen and phosphorus. Table 6-3 gives the overall relative effectiveness for nitrogen and
phosphorus for the watershed jurisdictions by major river basin for above and below the fall line.
The relative effectiveness numbers are separate for WWTPs and all other sources. The
distinction is made because of the following:
1. There is a wide disparity in the percent loading from WWTPs when comparing one basin
to another.
2. On the basis of information in Appendix K, it is EPA's professional judgment that
WWTPs can achieve a much higher percent of controllable load than that for other
sources.
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Chesapeake Bay TMDL
The difference in relative effectiveness is because of the geographic location of the sources. For
example, in the Maryland western shore basin, the majority of the wastewater treatment load is
discharged directly to tidal waters, whereas a significant fraction of all other sources are
upstream, including areas that are above reservoirs with very low delivery factors.
Table 6-3. Relative effectiveness (measured as DO concentration per edge-of-stream pound
reduced) for nitrogen and phosphorus for watershed jurisdictions by major river basin and above
and below the fall line
Jurisdiction
District of Columbia
District of Columbia
Delaware
Delaware
Delaware
Maryland
Maryland
Maryland
Maryland
Maryland
Maryland
Maryland
Maryland
Maryland
New York
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Virginia
Virginia
Virginia
Virginia
Virginia
Virginia
Virginia
Virginia
Virginia
West Virginia
West Virginia
Basin
Potomac above Fall Line
Potomac below Fall Line
Lower East Shore
Middle East Shore
Upper East Shore
Lower East Shore
Middle East Shore
Patuxent above Fall Line
Patuxent below Fall Line
Potomac above Fall Line
Potomac below Fall Line
Susquehanna
Upper East Shore
West Shore
Susquehanna
Potomac above Fall Line
Susquehanna
Upper East Shore
West Shore
East Shore VA
James above Fall Line
James below Fall Line
Potomac above Fall Line
Potomac below Fall Line
Rappahannock above Fall Line
Rappahannock below Fall Line
York above Fall Line
York below Fall Line
James above Fall Line
Potomac above Fall Line
&l
S 'c
6.09
6.17
7.93
4.13
6.75
7.88
6.91
1.89
6.38
3.32
6.17
9.39
7.49
7.83
5.60
2.10
6.99
5.50
2.23
5.72
0.23
0.79
1.45
5.54
1.05
4.48
0.37
1.85
0.06
1.34
All other
nitrogen
6.09
5.15
7.30
4.74
6.75
7.37
6.49
1.25
6.20
3.25
4.86
8.68
7,27
4.98
4.58
1.98
6.44
5.95
2.23
5.72
0.25
0.61
1.97
3.54
0.83
4.41
0.31
1.77
0.06
1.72
WWTP
phosphorus
3.08
6.17
7.97
5.51
7.10
7.89
6.92
1.66
6.38
2.99
' 6.12
9.11
7.49
7.68
4.25
3.08
4.38
6.12
2.61
5.72
0.33
0.79
3.08
5.49
2.10
4.48
0.43
1.85
0.34
2.12
All other
phosphorus
3.08
5.62
7.46
5.83
7.10
7.55
6.71
1.58
6.10
2.99
5.75
8.77
7.40
6.13
4.11
3.08
4.58
6.47
2.61
5.72
0.31
0.70
3.08
4.62
2.10
4.47
0.40
1.82
0.34
2.89
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December 29, 2010
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Chesapeake Bay TMDL
Figure 6-4 illustrates the relative effectiveness scores for nitrogen of the major river basins
provided in Table 6-3 in descending order.
t
JMDDEMDjMqpAf.lDlDCMDJDE
Stat*$- Basins
Source: Table 6-3
Figure 6-4. Relative effectiveness for nitrogen for the watershed jurisdictions and major rivers basins, above
and below the fall line, in descending order.
Figure 6-5 and Figure 6-6 provide additional graphical illustration of the relative effectiveness
concept for all the basins in the watershed related to nitrogen and phosphorus loading,
respectively. The figures illustrate that, on a per-pound basis, a large disparity exists among
basin loads on the effect of DO concentrations in the Bay. Generally, the northern and eastern
river basins have a greater effect on water quality than do other basins.
6.3.2 Determining Controllable Load
Modeling in support of developing the Chesapeake Bay TMDL employs two theoretical
scenarios that help to illustrate the load reductions in the context of a controllable load.
The No Action scenario is indicative of a theoretical worst case loading situation in which no
controls exist to mitigate nitrogen, phosphorus, and sediment loads from any sources. It is
specifically designed to support equity among basin-jurisdiction allocations in that the levels of
all control technologies, BMPs. and program implementation are completely removed.
The E3 scenario—everything by everyone everywhere—represents a best-case possible situation,
where a certain set of possible BMPs and available control technologies are applied to land,
given the human and animal populations, and wastewater treatment facilities are represented at
highest technologically achievable levels of treatment regardless of costs. Again, it considers
equity among the allocations in that the levels of control technologies, BMPs, and program
implementation are the same across the entire watershed.
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December 29, 2010
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Chesapeake Bay TMDL
Effectiveness
Nitrogen
^ 00-12
m 13-27
28-4.2
43-55
HI 5.6-71
•I 72-10.3
-<*>
Figure 6-6. Relative effectiveness illustrated geographically by subbasins across the Chesapeake Bay
watershed for nitrogen.
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December 29, 2010
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Chesapeake Bay TMOL
Effectiveness
Phosphorus
B 00-16
H 1.7-3 1
3248
49-57
H 58-71
•• 72-103
Figure 6-6. Relative effectiveness for illustrated geographically by subbasins across the Chesapeake Bay
watershed for phosphorus.
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December 29, 2010
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Chesapeake Bay TMDL
The gap between the No Action scenario and the E3 scenario represents the maximum theoretical
controllable load reduction that is achievable by fully implementing the control technologies
included in E3 scenario. Those and other key reference scenarios are defined and documented in
detail in Appendix J.
Each scenario can be run with any given year's land-use representation. The year 2010 was
selected as the base year because it represents conditions at the time the Bay TMDL is
developed. Thus, the 2010 No Action scenario represents loads resulting from the mix of land
uses and point sources present in 2010 with no effective controls on loading, while the 2010 E3
scenario represents the highest technically feasible treatment that could be applied to the mix of
all land use-based sources and permitted point sources in 2010 (Table 6-4).
Basinwide, anthropogenic, controllable loads are determined by subtracting the basinwide E3
load from the basinwide No Action load. Calculated percentage ofES is used as a comparative
tool for assessing the relative level of effort between various loading reduction scenarios.
Table 6-4. Pollutant sources as defined for the No Action and E3 model scenarios
Model source
Land uses
Wastewater
Dischargers
CSOs
Atmospheric
deposition
Scenario
No Action
No BMPs applied to the land
Significant municipal WWTPs
Flow = design flows
TN = 18mg/L
TP = 3 mg/L
BOD = 30 mg/L
DO = 4. 5 mg/L
TSS = 15 mg/L
Non-significant municipal VWVTPs
Flow = existing flows
TN = 18mg/L
TP = 3 mg/L
BOD = 30 mg/L
DO = 4.5 mg/L
TSS = 15 mg/L
Flow = 2003 base condition flow
TN = 2003 load estimate
TP = 2003 load estimate
BOD = 2003 load estimate
DO = 2003 load estimate
TSS = 2003 load estimate
1985 Air Scenario
E3 = Everyone Everything
Everywhere
All possible BMPs applied to land given
current human and animal population
and land use
Significant municipal VWVTPs
Flow = design flows
TN = 3 mg/L
TP = 0.1 mg/L
BOD = 3 mg/L
DO = 6 mg/L
TSS = 5 mg/L
Non-significant municipal VWVTPs
Flow = existing flows
TN = 8 mg/L
TP = 2 mg TP/1
BOD = 5 mg/L
DO = 5 mg/L
TSS = 8 mg/L
Full storage and treatment of CSOs
2030 Air Scenario, max reductions
Source: Appendix J
Note: BOD = biological oxygen demand; DO = dissolved oxygen; TN = total nitrogen; TP = total phosphorus; TSS =
total suspended solids
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December 29, 2010
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Chesapeake Bay TMDL
6.3.3 Relating Relative Impact to Needed Controls (Allocations)
I'D applv the allocation methodology, loads from each major river basin were divided into two
categories wastewater and all other sources (Figure 6-7). The rationale for such separate
accounting is the higher likelihood of achieving greater load reductions for the wastewater sector
than lor other source sectors (Appendix K). In addition there \vas a wide disparity between basin
and jurisdictions on the fraction of the load coming from the wastewater sector as opposed to
other sectors Therefore, that disparitv is addressed b> separate accounting for the wastewater
sector from the other sectors in the allocation methodolog}. Wastewater loads included all major
and minor municipal, industrial and CSO discharges. Then lines were drawn for each of the two
source categories such that the addition of the two lines would equal the basinwide nitrogen and
phosphorus loading targets for nitrogen and phosphorus.
I sing the general methodology described above, the CBP partners considered many different
combinations of wastewater and other sources controls and slopes of the lines on the allocation
graph (Appendix K). After discussing the options at length, the following graph specifications
were general!) accepted b\ the partners and determined to be appropriate by EPA.
I he \\asiewater line was set first and would be a hocke> stick shape with load reductions
increasing with relative effectiveness until a maximum percent controllable load was reached.
lor nitrogen
• The maximum percent controllable load was 90 percent, corresponding to an effluent
concentration of 4.5 mg/l.
• I he minimum percent controllable load was 67 percent, corresponding to an effluent
concentration of 8 mg L
I or phosphorus
• I he maximum percent controllable load was 96 percent, corresponding to an effluent
concentration of 0.22 mg/l..
• I he minimum percent controllable load was 85 percent, corresponding to an effluent
concentration of 0.54 mg T.
1 or both the nitrogen and phosphorus wastewater lines
• Anv relative effectiveness that was at least half of the maximum relative effectiveness value
was given maximum percent controllable.
• I he minimum controllable load value was assigned to a relative effectiveness of zero, and
all values of relative effectiveness between zero and half of the maximum value were
assigned interpolated percentages (Figure 6-7).
I he other sources line was set at a level that was necessary to achieve the basinwide load needed
lor achieving the DO standards in the middle mainstem Bay and lower tidal Potomac River
segments. That line was set at a slope such that there was a 20 percent overall difference from
highest controllable load to lowest, ranging from 56 percent of controllable loads for basins with
low relative effectiveness to 76 percent of controllable loads for basins with high relative
effectiveness for nitrogen (Figure 6-7) The slope was chosen as the most supported by the
6-24 December 29, 2010
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Chesapeake Bay TMDL
jurisdiction partners after exploring many options. The slope provides a balance of enough relict
of controls for the less effectiveness basins yet still requires significant controls for all basins.
For each category—\vastewater and all other sources—loads are aggregated b\ major basin and
reductions are assigned according to the process detailed above. The graph in Figure 6-7
illustrates the methodology for the total nitrogen target load of 190 million Ibs per year.
| -*-ABOih«r|
• **?!?
TN, pS.3. goiMW, WWTP < 4.5-1 m»X ortwt
r j
100% ^^^^^^^^^^^^^^^^^^^^^^^«^^^^_
90S jr-
30%
20%
10%
0%
10
Figure 6-7. Allocation methodology example showing the hockey stick and straight line reductions
approaches, respectively, to wastewater (red line) and all other sources (blue line) for nitrogen.
6.4 Establishing the Basin-Jurisdiction Allocations for Nitrogen and
Phosphorus
This subsection describes the application of all the processes described earlier in this section.
EPA identified the nitrogen and phosphortis allocations to the basin-jurisdictions in a letter on
July 1 . 2010. from the EPA Region 3 Administrator to the seven watershed jurisdictions (L'SI P \
201 Of). The allocations to the seven watershed jurisdictions were derived to achieve Chesapeake
Bay WQS recently adopted by the four Bay jurisdictions.
The Bay jurisdictions' WQS are described in Section 3.3. The allocations in the letter cited
above are the allocations on which the jurisdictions based their draft and final Phase I WIPs. The
full process for establishing the nitrogen and phosphorus basin-jurisdiction allocations is
described below:
• Established the atmospheric deposition allocations on the basis of addressing the
requirements of the CAA to meet existing national air quality standards out through 2020.
• Set the basinwide nitrogen and phosphorus loads on the basis of attaining the applicable DO
criteria in those Bay segments (middle Chesapeake Bay mainstem and the lower tidal
Potomac River) and designated uses (deep^vater and deep-channel) whose water quality
6-25 December 29, 2010
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Chesapeake Bay TMDL
conditions are influenced by major river basins and jurisdictions throughout the Bay
watershed.
• Distributed the basinwide nitrogen and phosphorus loads by major river basin and
jurisdiction following the methodology developed by the partnership (see Section 6.2).
• Made certain discretionary adjustments to the allocations to New York and West Virginia.
• Allowed for individual jurisdictions to exchange nitrogen and phosphorus loads within and
between their major river basins using specific exchange ratios, as long as the exchanges
still resulted in attainment of all WQS.
• Identified those individual Bay segments still not attaining their applicable DO/chlorophyll
a WQS at the allocated basinwide nitrogen and phosphorus loads and addressed the
remaining nonattainment segments.
• Derived the final basin-jurisdiction nitrogen and phosphorus allocations to achieve the
applicable WQS for DO and chlorophyll a in all 92 Bay segments.
Individual jurisdictions further suballocated their major river basin-jurisdiction allocated loads
within their Phase I WIPs down to their respective Bay segment watersheds in their jurisdiction.
After in-depth review of the final Phase I WIPs and the public comments, EPA made final
determinations on the allocations as described in Section 8.
6.4.1 Setting the Atmospheric Nitrogen Deposition Allocation
Atmospheric deposition of nitrogen is the major source of nitrogen to the Chesapeake Bay
watershed, greater than the other sources of fertilizer, manures, or point sources. For that reason,
it is necessary to allocate an allowable loading of nitrogen from air deposition in the Chesapeake
Bay TMDL. The nitrogen loadings come from many jurisdictions outside the Chesapeake Bay
watershed. Figure 6-8 shows the approximate delineation of the Bay airshed. Seventy-five
percent of the nitrogen air deposition loads to the Chesapeake watershed originate from sources
within the Bay airshed, with twenty-five percent originating from sources beyond the airshed,
and in the largest sense, the source of atmospheric loads to the Chesapeake Bay watershed are
global. That is reflected in the Bay Airshed Model, which has a domain of all North America
(with boundary conditions to quantify global nitrogen sources). About 50 percent of the oxidized
nitrogen (NOx) atmospheric deposition loads to the Chesapeake watershed and tidal Bay come
from the seven Bay watershed jurisdictions. For more detailed discussion, see Appendix L.
By including air deposition in the Bay TMDLs LAs, the Bay TMDL accounts for the emission
reductions that will be achieved by seven watershed jurisdictions and other states in the larger
Bay airshed. If air deposition and expected reductions in nitrogen loading to the Bay were not
included in the LAs, other sources would have to reduce nitrogen discharges/runoff even further
to meet the nitrogen loading cap. Because CAA regulations and programs will achieve
significant decreases in air deposition of nitrogen by 2020, EPA believes the TMDL inclusion of
air allocations (and reductions) is based on both the best available information with a strong
reasonable assurance that those reductions will occur. The TMDL developed for the Chesapeake
Bay will reflect the expected decreases in nitrogen deposition and the 2-year federal milestones
will track the progress of CAA regulations and programs.
6-26 December 29, 2010
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Chesapeake Bay TMDL
REDUCED
OXIDIZED
Source: Dr. Robin Dennis, USEPA/ORD/NERUAMAD/AEIB
Figure 6-8. Principal areas of nitrogen oxide (blue line) and
ammonia (red line) emissions that contribute to nitrogen
deposition to the Chesapeake Bay and its watershed (dark blue fill).
In determining the allowable loading from air deposition, EPA separated the nitrogen
atmospheric deposition into two discreet parcels: (1) atmospheric deposition occurring on the
land and nontidal waters in the Bay watershed, which is subsequently transported to the Bay; and
(2) atmospheric deposition occurring directly onto the Bay tidal surface waters.
•
The deposition on the land becomes part of the allocated load to the jurisdictions because the
atmospheric nitrogen deposited on the land becomes mixed with the nitrogen loadings from the
land-based sources and, therefore, becomes indistinguishable from land-based sources.
Furthermore, once the nitrogen is deposited on the land, it would be managed and controlled
along with other sources of nitrogen that are present on that parcel of land. In contrast, the
atmospheric nitrogen deposited directly to tidal surface waters is a direct loading with no land-
based management controls and, therefore, needs to be linked directly back to the air sources and
air emission controls. For more detailed discussion, see Appendix L.
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December 29, 2010
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Chesapeake Bay TMDL
EPA included an explicit basinvvide nitrogen atmospheric deposition allocation in the Bay
TMDL and determined it to be 15.7 million pounds per year of nitrogen atmospheric deposition
loads direct to Chesapeake Bay tidal tributary and embayment waters (Appendix L) (see Section
9.1). Activities associated with implementation of CAA regulations by EPA and the jurisdictions
through 2020 will ensure achievement of that allocation and are already accounted for within the
jurisdictions' major river basin nitrogen allocations. Any additional nitrogen reductions realized
through more stringent air pollution controls at the jurisdictional level, beyond minimum federal
requirements to meet air quality standards, may be credited to the individual jurisdictions
through future revisions to the jurisdictions' WIPs, 2-year milestones, and the Chesapeake Bay
TMDL tracking and accounting framework (Appendix L).
In determining the amount of air controls to be used as a basis for the Bay TMDL air allocation,
HPA relied on current laws and regulations under the CAA. Those requirements, together with
national air modeling analysis, provided the resulting allocated air load from direct deposition to
the tidal surface waters of the Bay and its tidal tributaries (Appendix L).
1 he air allocation scenario represents emission reductions from regulations implemented through
the CAA authority to meet National Ambient Air Quality Standards for criteria pollutants in
2020. The air allocation scenario includes the following:
• The Clean Air Interstate Rule (CAIR) with second phase and the Clean Air Mercury Rule
(CAMR)
• The Regional Haze Rule and guidelines for Best Available Retrofit Technology (BART)
• The On-Road Light Duty Tier 2 Rule
• The Clean Heavy Duty Truck and Bus Rule
• The Clean Air Non-Road Diesel Tier 4 Rule
• The Locomotive and Marine Diesel Rule
• The Non-road Large and Small Spark-Ignition Engines Programs
• The Hospital/Medical Waste Incinerator Regulations
The controls described above were modeled using the Community Multiscale Air Quality
(CMAQ) national model, which enabled quantification of deposition direct to the Chesapeake
Bay tidal waters to be determined. Information on the CMAQ modeling analysis is at
hup://w\v\v.epa.uov/cair/technical.html. That approach is the basis for the previously mentioned
15.7 million pounds per year as the allocation in the Bay TMDL for air deposition directly to the
tidal waters. Appendix L provides a more detailed description of the process for establishing the
atmospheric deposition allocations for nitrogen.
6.4.2 Determining the Basinwide Nitrogen and Phosphorus Target Load
Based on Dissolved Oxygen
With the air allocated loads being set at 15.7 million pounds per year, the next step in the process
was to determine the basinwide nitrogen and phosphorus loadings that would cause the mainstem
Bay and major tidal river segments—all influenced by nitrogen and phosphorus loads from
multiple jurisdictions—to achieve all the applicable DO WQS. Numerical chlorophyll a WQS
6-28 December 29, 2010
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Chesapeake Bay TMDL
were not used for this basinwide loading determination because they apply to only the tidal
James River and the District of Columbia's tidal waters of the Potomac and the Anacostia rivers
and, therefore, are not affected by the other basins in the watershed. The principal Bay segments
that were most important for determining the basinwide nitrogen and phosphorus loads were the
middle mainstem Bay segments CB3MH, CB4MH. and CB5MH (Maryland and Virginia) and
the lower tidal Potomac River segment POTMH_MD because their water quality conditions are
influenced by all river basins through the Bay watershed. Therefore, achieving attainment in
those segments will necessitate nitrogen and phosphorus reductions from all basins.
The process used for determining the load that will achieve the DO WQS in these segments was
to progressively lower the nitrogen and phosphorus loadings simulated in the Bay Water Quality
Model and then assess DO WQS attainment for each loading scenario. Numerous iterations of
different load scenarios were run until the appropriate nitrogen and phosphorus loadings to
achieve WQS could be determined (Appendix M).
Figure 6-9 shows the numerous water quality model runs that were performed at various loading
levels and the resulting DO standards attainment results. The water quality measure on the
vertical axis is the number of Bay segments that were not attaining the applicable Bay DO WQS.
As can be expected, as loadings are lowered throughout the Bay watershed, the number of DO
DO Criteria Attainment under Various Load Scenarios
g30
\
\
* Open Water Violations
• Deep Water Violations
— * — Deep Channel Violations
10
Basin-wide load is
190 N and 12.7P (MPY)
1985 Ba*e 2009
Scenario Calibration Scenario
342TN 309TN 248TN
24.1TP 19.STP 18.6TP
Tributary
Strategy
191TN
14.4TP
Loading Loading
Scenario Scenario
190TN 179TN
12.7TP 12.0TP
Loading E3
Scenario Scenario
170TN 141TN
11.3TP 8.5TP
Note: This graph expands some of the 92 TMDL segments into separate jurisdiction-segments so that the total
numbers of open-water, deep-water, and deep-channel designated use segments are 98, 14, and 11, respectively
Figure 6-9. Chesapeake Bay water quality model simulated DO criteria attainment under various TN and TP
loading scenarios.
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December 29, 2010
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Chesapeake Bay TMDL
WQS non-attaining segments was reduced. At the loading of 190 million pounds per year of
nitrogen and 12.7 million pounds per year of phosphorus, and after considering other lines of
evidence beyond the Bay Water Quality and Sediment Transport Model, as presented in
Appendix N, only one Bay segment was in nonattainment for DO—lower Chester River. For the
lower Chester River segment, nonattainment persisted even to extremely low loading levels.
Therefore, Maryland adopted, and EPA approved a restoration variance for that segment. The
final allocations for the Bay will attain that restoration variance for DO. It should be noted that
the critical segments of CB3MH, CB4MH, and CB5MH for deep-channel and CB3MH,
CB4MH, CB5MH, and POTMH for deep-water were among the last segments to come into
attainment. Watershed-wide reductions will be needed to attain WQS in these segments.
Therefore, EPA determined that basinwide nitrogen loadings of 190 million pounds per year and
phosphorus loadings of 12.7 million pounds per year were sufficient to attain the main Bay DO
standards; as a result, EPA distributed those loadings among the major river basins and
jurisdictions in the Chesapeake Bay watershed.
6.4.3 Allocating Nitrogen and Phosphorus Loads to Jurisdictions within
the Bay Watershed
After more than 2 years of discussion and exploration by EPA and the jurisdictions of many
different approaches to allocating allowable loads to each of the jurisdictions and major basins, a
consensus could not be reached for an approach for allocating loads to all jurisdictions. With the
exception of New York and West Virginia, all the watershed jurisdictions agreed to the method
described above for allocating loadings to the major river basins and jurisdictions. EPA then
chose to use that method as described above to distribute the loadings based on the equity and
near consensus of the jurisdictions. Using that method, EPA calculated the relative effectiveness
of each of the major river basins in the Bay watershed and plotted as dots on the lines in Figures
6-10 (for phosphorus) and 6-11 (for nitrogen) to determine the basin-jurisdiction allocation
represented by each of the points. On the vertical axis is the percent of controllable load
(represented in the graph as No Action Minus E3 load) that would correspond to the allocated
load for each basin-jurisdiction. For example, 100 percent represents a loading such that all
sources would have all control technologies and practices approved by the partnership installed
(E3). The horizontal axis represents the relative effectiveness of each of the basin-jurisdictions, a
measure of the impact that a pound of nitrogen and phosphorus has on the DO concentrations in
the Chesapeake Bay. EPA first constructed the wastewater (WWTP) line (red line in Figures 6-
10 and 6-11) on the basis of the removal efficiencies of established treatment technologies.
EPA then constructed the other sources line (blue line in Figures 6-10 and 6-11) by having a
difference of 20 percent of controllable load when comparing facilities/lands in the basin-
jurisdiction with the highest relative effectiveness with the facilities/lands in the basin-
jurisdiction with the lowest relative effectiveness. As can be seen in Figure 6-10 and Figure 6-11,
facilities/lands in those basin-jurisdictions that have the highest effectiveness (or impact on the
Bay) on a per-pound basis must install the most controls (the basin-jurisdictions on the right of
the graph). While it is too cluttered to show each of the basin-jurisdictions on these graphs, see
Table 6-3 to identify the relative effectiveness for each basin and then find that point on these
graphs. Because the dots represent the various basin-jurisdictions in the watershed, the percent of
controllable load can be converted to the actual allocated load to achieve the Bay DO WQS.
6-30 December 29, 2010
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Chesapeake Bay TMDL
TP, p5.3, goaN13 WWTP = .22 - .54 mg/l, othei: max=min+20%,
. , ~
4 6
Relative Effectiveness
Figure 6-10. Example allocation methodology application for phosphorus.
-All Other
WWTP
TN, p5.3, goal=190, WWTP = 4.5-8 mg/l, other: max=min+20%
100%
90%
uj 80%
o
£ 70%
Z
*§ 60%
5 50%
40%
.2 30%
i
•§ 20%
I 10%
£ 0% f
0246
Relative Effectiveness
Figure 6-11. Example allocation methodology application for nitrogen.
10
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Chesapeake Bay TMDL
Finally, EPA added the allocated load for wastewater (WWTP) to the allocated load for other
sources to determine the total allocated load for each basin-jurisdiction. It must be noted that
although the graph separates wastewater and other sources, this does not necessarily require the
jurisdictions to use that separate wastewater or other sources loading in their WIPs for
suballocating the loads.
6.4.4 Resolving Dissolved Oxygen and Chlorophyll a Nonattaining Bay
Segments
After determining the target basinwide nitrogen and phosphorus allocations and distributing
those loads to the major basins and jurisdictions using the methodology illustrated above, EPA
identified seven designated-use segments for which the Bay Water Quality Model was predicting
nonattainment of the applicable Bay DO WQS (see Table 6-5). Those seven segments out of
attainment for the open-water designated use represent less than 1 percent of the total volume of
open-water habitats in entire Chesapeake Bay.
The Bay Water Quality Model also predicted nonattainment for numeric chlorophyll a. All five
Bay segments of the tidal James River in Virginia and the two Bay segments in the District of
Columbia (tidal Potomac and Anacostia rivers). On the basis of Bay Water Quality Model runs at
the basinwide nitrogen and phosphorus loading of 190 million pounds per year nitrogen and 12.7
million pounds per year phosphorus allocated by major river by jurisdiction the Bay Water
Quality Model predicted those seven segments to be in nonattainment of each jurisdiction's
respective numeric chlorophyll a WQS. This section explores the process by which EPA
examined Bay Water Quality Model results showing persistent nonattainment at reduced loading
levels and other evidence to make determinations regarding the loadings that would be sufficient
to attain the respective WQS for each of the Bay segments.
Dissolved Oxygen Nonattaining Segments
EPA examined the reasons of persistent nonattainment in these segments. Upon further review of
the model results for the non-attaining segments, along with other lines of evidence (including
water quality monitoring) and application of best professional judgment, EPA determined that
190 million pounds per year TN and 12.7 million pounds per year TP allocated by major river by
jurisdiction would be sufficient for these segments to attain the respective DO criteria (see
Appendix N). It was generally found that predicted nonattainment in a Bay segment resulted
from two or more of the following factors:
1. Less-than-expected change in DO concentrations from the calibration scenario to a given
reduced nitrogen and phosphorus load scenario
2. Poor agreement between model-simulated and historically observed DO concentrations
for a particular location and historical period
3. A limited number of unusually or very low DO concentrations that the Bay Water Quality
Model predicted were very difficult to bring into attainment of the open-water DO
criteria even with dramatically reduced loads
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The majority of those segments are in small and relatively narrow regions of the Bay's smallest
tidal tributaries. Such conditions constrain the Bay Water Quality Model's ability to effectively
integrate multiple drivers of DO concentrations. As a result, the Bay Water Quality Model's
ability to simulate the water quality changes in response to dramatically reduced loads was also
limited. In such cases, additional lines of evidence were used to determine whether a segment
could be expected to achieve the applicable WQS under the reduced nitrogen and phosphorus
loads (Appendix N).
EPA evaluated each Bay segment to determine: (1) whether violations of the DO criteria were
isolated or widespread; (2) whether nearby Bay segments also exhibited persistent or widespread
hypoxia or both; and (3) whether the Bay Water Quality Model predicted sufficient
improvements in DO concentrations to achieve DO WQS in nearby deeper, wider segments.
Results of the evaluations, documented in detail in Appendix N, are summarized as follows.
Following the comprehensive evaluation of the modeling results, application of the factors
described above, and inclusion of alternative lines of evidence, all seven segments were
determined to be in attainment of applicable WQS.
Results of the segment-specific evaluations, documented in detail in Appendix N, are
summarized as follows.
Gunpowder River (GUNOH)
Monitored DO concentrations over the 10-year period of 1991-2000 were almost universally
well above the 30-day mean open-water criterion of 5 mg/L. A single instance of moderate
hypoxia, combined with poor model agreement and an almost complete lack of response by the
Bay Water Quality Model to load reductions in the monitored location for the relevant month,
resulted in persistent nonattainment across all reduced loading scenarios for the month in
question. In contrast, nearby Bay segments—Bush River (BSHOH), Middle River (MIDOH),
and upper Chesapeake Bay (CB2OH)—all attained their respective DO WQS when loads were
reduced to the target basinwide allocation of 190 million pounds per year TN and 12.7 million
pounds per year TP (Appendix N). Given those factors, including the poor predictive
performance of the model in the Gunpowder River and 10 years of observed attainment of the
DO criteria at relatively high nutrient loadings, EPA finds with a reasonable degree of certainty
that target loadings of 190 million pounds per year TN and 12.7 million pounds per year TP will
be sufficient for the Gunpowder River segment to attain the DO WQS.
Manokin (MANMH), Maryland Anacostia (ANATF_MD), West Branch Elizabeth (WBEMH),
Pamunkey (PMKTF), and Wicomoco (WICMH) Rivers
Similar to the Gunpowder River segment, few violations of the open-water DO criteria occurred
in these five Bay segments, and Bay Water Quality Model simulations did not match well with
historically observed water quality conditions. The Bay Water Quality Model often failed to
simulate hypoxia for these locations under observed loads; thus, it was also unable to estimate
improved DO concentrations when nitrogen and phosphorus loads were reduced. Nearby deeper,
wider regions generally attained DO WQS at or before the target basinwide loadings. For more
discussion and data, see Appendix N. Given those factors, observed historic attainment with
existing criteria at current high nutrient loadings and limited predictive capacity of the model for
6-34 December 29, 2010
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Chesapeake Bay TMDL
those unique segments, EPA finds with a reasonable degree of certainty that target loadings of
190 million pounds per year TN and 12.7 million pounds per year TP will be sufficient for these
Bay segments to attain the DO WQS.
Magothy River (MAGMH)
Summer hypoxic conditions were not uncommon in the Magothy River from 1991 to 2000,
particularly when episodes of water column stratification prevented mixing of the bottom waters
with more oxygenated surface waters. Maryland adopted (and EPA approved) an episodic deep-
water designated use applicable to MAGMH to account for periods of water column
stratification (USEPA 2010a). However, some violations of the deep-water DO 30-day mean
criterion of 3.0 mg/L persisted even when nitrogen and phosphorus loads were reduced to the
target basinwide allocation (Appendix N). Because of the small, embayment nature of the
Magothy River, the Bay Water Quality Model was unable to reliably simulate observed
conditions in MAGMH or consistently estimate a response of sufficiently improved DO in
response to load reductions. However, the deep-water region of the adjacent mainstem segment
CB3MH attained its DO WQS well before the target basinwide nitrogen and phosphorus LAs
(Appendix N). Given the poor simulation of MAGMH conditions by the Bay Water Quality
Model, the significant load reductions already required of the Magothy River basin at the target
basinwide LAs, the considerable influence of the mainstem Chesapeake Bay on MAGMH water
quality conditions, and the predicted attainment of CB3MH deep-water well before the target
basinwide loading, EPA determined that MAGMH can reasonably be expected to attain its DO
WQS at the target loadings of 190 million pounds per year TN and 12.7 million pounds per year
TP.
Chlorophyll a Nonattaining Segments
Potomac and Anacostia Rivers in DC
The Bay Water Quality Model projected that the District of Columbia's portions of the Potomac
and Anacostia River segments would be in nonattainment of the applicable numeric chlorophyll
a WQS at the basinwide nitrogen and phosphorus target loads allocated to those two river basins.
However, through diagnostic analysis of the modeled chlorophyll a simulations for the Potomac
and Anacostia rivers in the District of Columbia, EPA determined that the Bay Water Qualiu
Model does not reliably simulate measured chlorophyll a levels. Therefore, other lines of
evidence (i.e., monitoring data) were weighed more heavily by EPA in the attainment
determination (Appendix N). Through further investigation. EPA analyzed recent chlorophvll <;
data for the two segments. The actual monitoring data show that the Potomac River segment is
attaining the District's chlorophyll a WQS and has been attaining that standard for at least the
past 7 years (Figure 6-12). Applying a similar assessment of recent water quality monitoring data
to the Anacostia River segment, a 4 percent level of nonattainment was determined
(Appendix N).
Because those two segments are at, or near, attainment of the current chlorophyll a WQS on the
basis of analysis of recent monitoring data and that additional nitrogen and phosphorus loading
reductions will occur as a result of the current allocations. EPA has concluded that both of the
Bay segments will be in full attainment with the chlorophyll a WQS under these nitrogen and
phosphorus allocations (Appendix N). Additionally, a TMDL for biochemical oxygen demand
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Chesapeake Bay TMDL
Potomac Tidal Fresh
Chi a Monitoring Data
MO Station TF2.1 —Standard
Sample Date
Source: http://www.chesapeakebay.net
Note: The DC station PMS44 is on the tidal Potomac River at the Woodrow Wilson Memorial Bridge (50 meters
upstream of the draw span). The MD station TF2. 1 is on the tidal Potomac River at Buoy 77 off the mouth of
Piscataway Creek.
Figure 6-12. Potomac River chlorophyll a monitoring data compared with the District's summer seasonal
mean chlorophyll a water quality criteria.
and nitrogen and phosphorus was approved by EPA in 2008 for the Anacostia River Basin
Watershed in Montgomery and Prince Georges Counties, Maryland and the District of Columbia
(MDE and DC DOE 2008). That TMDL for the Anacostia River requires significant reductions
that, when implemented, will result in attainment of the chlorophyll a WQS.
James River in Virginia
Similar to the EPA analysis of attainment of the District of Columbia's chlorophyll a criteria
using upper tidal Potomac and Anacostia rivers chlorophyll a monitoring data, EPA also
assessed attainment using chlorophyll a monitoring data for the tidal James River. In contrast to
the District's tidal Anacostia and Potomac River segments, EPA found that the past and current
monitoring data for most of the tidal James River segments showed significant nonattainment of
Virginia's chlorophyll a WQS. More recently, the Virginian-Pilot on August 12, 2010, reported
on algal blooms in the southern Bay region including the James River. An example of the
comparative analysis of the monitored data for the James as compared to Virginia's segment-
season specific chlorophyll a criteria is shown in Figure 6-13. EPA, therefore, has concluded that
nutrient controls beyond the present controls are needed in the James and EPA continued to rely
on the model results in assessing conditions and determining the appropriate allocations of
nitrogen and phosphorus.
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December 29, 2010
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Chesapeake Bay TMDL
Surface Chlorophyll a
1985 - 2009
1985 1990
Source: http://www.chesapeakebay.net
1995
2000
2005
Figure 6-13. Tidal James River monitoring data for chlorophyll a at station TFS.5 (in the upper tidal James
River near Hopewell, Virginia) compared to Virginia's James River segment-season specific chlorophyll a
criteria.
In general, the Bay Water Quality Model is well-calibrated to the tidal James River and effectively
simulates average seasonal conditions in the five tidal segments of the river. The Bay Water Quality
Model also consistently estimates improved chlorophyll a conditions with increasing nitrogen and
phosphorus load reductions. At the same time, however, the model does not simulate individual algal
bloom events, which are highly variable and caused by numerous factors, some of which are still not
well understood by the scientific community (Appendix O). The chlorophyll a WQS adopted in
Virginia's regulation to protect the tidal James River were set at numerical limits for spring and
summer seasonal averaged conditions, not for addressing individual algal bloom events lasting hours
to days. Therefore, EPA's determination of nitrogen and phosphorus loadings required to attain
chlorophyll a WQS in the tidal James River was based on those years and Bay (James River)
segments for which the Bay Water Quality Model reliably simulated the water quality monitoring-
based chlorophyll a calibration data. EPA used that approach to determine the James River basin
allocation of 23.5 million pounds per year TN and 2.35 million pounds per year TP.
However, since the Bay Water Quality Model does not accurately simulate short-frequency,
individual bloom events, some segment and season-specific nonattainment remains at the target
James River allocation. Nonattainment of the summer chlorophyll a WQS persisted in the lower tidal
fresh James segment (JMSTFL) for the summer periods of 1995-2000 and in the James River mouth
segment (JMSPH) for the 1997-2000 summer periods (Appendix O). The Bay Water Quality Model
results for those nonattainment areas were not used to establish the allocations for the James River.
Figure 6-14 shows the number of segments and 3-year periods (segment-periods) in nonattainment of
Virginia's James River chlorophyll a WQS (out of the simulation period of 1991-2000) for the
various load scenarios simulated, using those model results where the model is reliably simulating
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December 29, 2010
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Chesapeake Bay TMDL
the calibration data. From the graph, it can be seen that the James River does not fully attain the
chlorophyll a WQS until a loading of 23.5 million pounds per year of nitrogen and 2.35 million
pounds per year of phosphorus was achieved. EPA set the necessary load allocations for nitrogen and
phosphorus at those levels.
James River Chlorophyll a Response to Load Reductions
James River Basin TN/TP Load
Figure 6-14. James River nonattainment of the chlorophyll a WQS at various load scenarios.
6.4.5 Allocation Considerations for the Headwater Jurisdictions
(New York and West Virginia)
The methodology described above for distributing the basinwide loading was accepted by all
jurisdictions except New York and West Virginia. From an additional Bay Water Quality Model
run, EPA determined that small amounts of additional loadings of nitrogen and phosphorus in
excess of the 190 million pounds per year TN and 12.7 million pounds per year TP could be
allocated and still attain applicable WQS. In the July I, 2010, letter to the jurisdictions, EPA
used its discretionary authority to allocate to New York an additional 750,000 pounds per year of
nitrogen (above the allocation calculated for New York using the method used to distribute the
basinwide loads of 190 million pounds per year of nitrogen and 12.7 million pounds per year of
phosphorus) (USEPA 2010g). With the final TMDL, EPA provided an additional 250,000
pounds per year of nitrogen and 100,000 pounds per year of phosphorus to New York's
allocation. In addition, EPA used its discretionary authority to allocate to West Virginia an
additional 200,000 pounds per year of phosphorus (above the level allocated to West Virginia
using the allocation methodology to distribute the basinwide load of 190 million pounds per year
of nitrogen and 12.7 million pounds per year of phosphorus) (USEPA 2010g). EPA, through
model analysis, confirmed that those loadings will achieve WQS in the Chesapeake Bay. EPA
provided the additional allocations for several reasons, including the following:
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Chesapeake Bay TMDL
• Following the principles and guidelines as expressed in Section 6.3. tributary basins that
contribute the most to the Bay water quality problems must do the most to resolve those
problems (on a pound-per-pound basis). The headwater jurisdictions of New York and
West Virginia contribute small portions of the overall nitrogen and phosphorus delivered to
the Bay (5 percent or less) and, therefore, are provided some relief in their allocations.
• The water quality of the Susquehanna River leaving New York appears to be of better
quality than that of downstream waters.
• The allocation methodology accommodates to some extent future growth by providing
WLAs for wastewater treatment facilities at design flow rather than actual flow, thereby
reserving a load for expansion of the facility. Therefore. New York considered the
methodology to be biased against Bay watershed jurisdictions that are growing relative!)
slowly, like New York.
• A cleaner Bay provides greater benefit (in terms of commercial and recreational benefits of
a cleaner bay) to the tidal jurisdictions than to the nontidal jurisdictions such as New York
and West Virginia.
6.4.6 Nitrogen-to-Phosphorus Exchanges
On the basis of recent science regarding the relationship between nitrogen and phosphorus, EPA
permitted the jurisdictions to propose the exchange of nitrogen and phosphorus loads within
major river basins at a 1:5 ratio for reducing existing allocated phosphorus loads in exchange for
increased nitrogen loads; and a 15:1 ratio for reductions in existing allocated nitrogen loads in
exchange for increased phosphorus loads. For example, in jurisdiction allocations, for every I
pound of phosphorus reduced, 5 pounds of nitrogen can be added and for every 15 pounds of
nitrogen reduced, 1 pound of phosphorus can be added. This section documents the technical
basis for those exchange rates.
Two scientific papers published in recent years specifically address tradeoffs between nitrogen
and phosphorus. While those two analyses were completed with earlier versions of the Bay
Watershed Model and the Bay Water Quality Model, the results are still meaningful if used to
put bounds on the exchanges on a Bay-wide scale.
Wang et al. (2006) published response surface plots for chlorophyll a concentrations and anoxic
volume days using a matrix of nitrogen and phosphorus load reduction scenarios. The response
surface plots were generated by applying equations predicting overall chlorophyll a
concentrations and anoxic volume days as quadratic functions of the nitrogen and phosphorus
fraction of 2000 loading levels. Applying the Bay Watershed Model generated values in these
same equations to assess the area around the allocation levels of 187.4 million pounds TN and
12.52 million pounds TP, one can use the derivatives of the original published equations to
determine estimated TN:TP exchange relationships.
Figure 6-15 illustrates the TN:TP exchange ratio for different levels of TP based on the Anoxic
Volume Days metric. At the allocation level of 12.52 million pounds of TP. the calculated
exchange ratio is about 9:1, but the ratio has a good deal of variability. Considering that those are
earlier versions of the Bay Watershed and Bay Water Quality models applied to the current
reduction percentages, the local exchange ratio can vary depending on the location of the basin
6-39 December 29, 2010
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Chesapeake Bay TMDL
within the Bay. Given the degree of variability in this graph, EPA adopted a conservative
approach. Figure 6-16 is the same analysis, except it uses chlorophyll a concentration in place of
Anoxic Volume Days. The exchange ratios are lower, putting a greater importance on TP overall.
TN / TP trade off based on Anoxic Volume Days
18
16
14
o
1 12
•
o»
S 10
1 8
10
11
12
13
TP Load
14
15
16
Source: Wang et al. 2006
Figure 6-15. TN:TP exchanges based on anoxic volume days and varying TP loads.
TN / TP exchange based on average Chlorophyll concentration
9
8
o
le
* 4
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Chesapeake Bay TMDL
Wang and Linker (2009) documented an application of the earlier Bay models to the deep-water
designated use of the upper central Chesapeake Bay segment CB4MH and determined a TN:TP
exchange ratio of roughly 5:1 for that region of the mainstem Bay.
Further, the stoichiometric Redfield ratio for algal cell is well established at 16:1 TN:TP. This is
the number of nitrogen and phosphorus atoms that approximates the nitrogen needed to make
algal proteins and the phosphorus needed to make algal nucleic acids. On a weight basis, which
is how one measures nitrogen and phosphorus loads delivered to the Bay, the TN/TP ratio
equates to 10:1 TN:TP.
Taking both of those analyses, the two published papers, and EPA's desire to be conservative on
these exchanges into account, an asymmetrical exchange ratio of 5:1 TN:TP when allowing more
nitrogen loads and lowering the phosphorus load, and a ratio of 15:1 TN:TP when allowing more
phosphorus loads and lowering the nitrogen load are applied. All applications of these TN:TP
exchanges are confirmed to not affect the attainment of the jurisdictions' Bay WQS through
follow-up Bay Water Quality Model scenarios.
Basin-Jurisdiction Nitrogen and Phosphorus Allocations
After performing all the analyses described above, EPA determined the basin-jurisdiction
allocations for nitrogen and phosphorus needed to attain the WQS for DO and chlorophyll a.
EPA sent a letter to the jurisdictions on July 1, 2010, to inform the jurisdictions of the allocations
(USEPA 2010g). The table of those allocations are in Section 6.7. The jurisdictions used the
allocations to develop their Phase 1 WIPs that further suballocate the nitrogen and phosphorus
loadings to finer geographic scales and to individual sources or aggregate source sectors.
6.5 Establishing the Sediment-Related Model Parameters
In the sampling of paniculate material in the streams and rivers of the Chesapeake Bay
watershed as well as within the tidal waters, almost all of the measurements are for total
suspended solids (TSS). This parameter includes sand, silt, and clay particles of sediment but
also includes paniculate organics. The Bay Watershed Model is calibrated to the observed TSS
values. Since TSS is predominantly sediment, total suspended solids and sediment are often
used interchangeably. Throughout the document, most of the references to allocations use the
term sediment as that is the pollutant that needs to be reduced, but the formal allocation tables
use the term TSS as that's the parameter output from the Bay models and its the parameter
causing the aquatic life impairment (e.g., reducing light from reaching SAV).
6.5.1 Critical Conditions for Water Clarity and SA V
Submerged aquatic vegetation or SAV responds negatively to the same suite of environmental
factors that result in low to no DO conditions—high-flow periods yielding elevated loads of
nitrogen, phosphorus, and sediment (Dennison et al. 1993: Kemp 2004). High levels of nitrogen
and phosphorus within the estuarine water column results in high level of algae, which block
sunlight from reaching the SAV leaves. The same high concentrations of nitrogen and
phosphorus also fuel the growth of epiphytes or microscopic plants on the surface of the SAV
leaves, also directly blocking sunlight. Sediment suspended in the water column reduces the
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Chesapeake Bay TMDL
amount of sunlight reaching the SAV leaves. Because the critical period for both DO and water
clarity/SAV are based on high-flow periods, EPA determined that the same critical period used
for IX) was appropriate for water clarity/SAV. Therefore, the critical period selected for
assessment of the jurisdictions' SAV/vvater clarity WQS was 1993-1995. Detailed technical
documentation is provided in Appendix G.
6.5.2 Assessment Procedures for the Clarity and SA V Standards
The Chesapeake Bay SAV restoration acreage in the jurisdictions' WQS are based on achieving
SAV acreage goals set forth in state WQS that were based on the highest SAV acreage ever
observed over a 40-year to more than 70-year historical record depending on the records
available for each basin (USEPA 2003a: 2003d). Bay-wide, the SAV restoration goal is 185.000
acres.
The linked SAV and water clarity WQS are unique in some respects. Rather than covering the
entire Bay as the DO WQS does, the SAV-vvater clarity WQS applies in only a narrow ribbon of
shallow water habitat along the shoreline in depths of 2 meters or less. That presents certain
challenges for the Chesapeake Bay model simulation and monitoring systems, both of which
have long been more oriented toward the open waters of the Chesapeake Bay and its tidal
tributaries and embayments. Scientific understanding of the transport, dynamics, and fate of
sediment in the shallow waters of the Chesapeake Bay and understanding and simulating all the
factors influencing SAV growth continues to develop. Appendix P provides more details of the
Chesapeake Bay Water Quality and Sediment Transport Model-based combined SAV-water
clarity attainment assessment procedures used in developing the sediment allocations.
The combined SAV/water clarity WQS can be achieved in one of three ways (see Section 3.3.3).
First, as SAV acreage is the primary WQS, the WQS can be achieved by the number of SAV
acres measured by way of aerial surveys—the method that is primarily used in CWA section
303(d) assessments. Second, the WQS can be achieved by the number of water clarity acres
(divided by a factor of 2.5) added to the measured acres of SAV. Third, water clarity criteria
attainment can be measured on the basis of the cumulative frequency distribution (CFD)
assessment methodology using shallow-water monitoring data.
Although SAV responds to nitrogen, phosphorus, and sediment loads, DO and chlorophyll a
primarily respond only to nitrogen and phosphorus loads. Because of that hierarchy of WQS
response, EPA developed the strategy to achieve WQS by first setting the nitrogen and
phosphorus allocation for achieving all the DO and chlorophyll a WQS in all 92 segments, and
then making any additional sediment reductions where needed to achieve the SAV/water clarity
WQS. That strategy is augmented by management actions in the watershed to reduce nitrogen,
phosphorus, and sediment loads.
Just as the SAV resource is responsive to nitrogen, phosphorus, and sediment loads, many
management actions in the watershed that reduce nitrogen and phosphorus also reduce sediment
loads. Examples include conservation tillage, farm plans, riparian buffers, and other key
practices. The estimated ancillary sediment reductions resulting from implementation actions
necessary to achieve the nitrogen and phosphorus reductions needed to achieve the allocations
are estimated to be about 40 percent less than 1985 sediment loads and 25 percent less than
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Chesapeake Bay TMDL
current (2009) load estimates. The sediment reductions associated with the nitrogen and
phosphorus controls necessary to achieve the basin-jurisdiction target loads provided on
July 1. 2010, are provided in Table 6-6.
Table 6-6. Tributary strategy scenario and nitrogen and phosphorus-based allocation scenario's
total suspended solids loads (millions of pounds) by watershed jurisdiction
Jurisdiction
Maryland
Pennsylvania
Virginia
District of Columbia
New York
West Virginia
Delaware
Total
Tributary strategy Allocation scenario
1,195 1,118
2,004
2,644
10
310
248
55
6,467
1,891
2,434
10
291
240
55
6,040
Using the Bay Water Quality Model, the SAV/water clarity WQS were assessed by starting with
measured area of SAV in each Bay segment from the 1993-1995 critical period. On the basis of
regressions of SAV versus load, the estimated SAV area, resulting from a particular nitrogen and
phosphorus or sediment load reduction, was estimated as described in Appendix P. Then the
estimated water clarity acres from the Bay Water Quality Model were added after adjustment by
a factor of 2.5 to convert to the water clarity acres to water clarity equivalent SAV acres
(Appendix P). Finally the water clarity equivalent SAV acres were added to the regression-
estimated SAV acres and compared to the Bay segment-specific SAV WQS.
Note that when assessing attainment using monitoring data, only the SAV acres measurement is
generally used because the number of Bay segments assessed with shallow-water clarity data are
still limited. When projecting attainment using the Bay Water Quality model, the extrapolated
measured SAV acres are added to the model-projected water clarity equivalent SAV acres to
determine total SAV acres (Appendix P).
6.5.3 Addressing Reduced Sensitivity to Load Reductions at Low
Nonattainment Percentages
Water Clarity
Only one segment displayed a small, yet persistent percentage of model projected water
clarity/SAV criteria nonattainment over a range of reduced nitrogen and phosphorus loads—the
Appomattox River segment (APPTF) in Virginia's James River Basin. In the case of that
segment, while historical records document observed SAV acres in the 1950s, no observed SAV
has been mapped since the early 1970s. That tidal fresh segment (salinities from 0 to 0.5 ppt) did
not exhibit a positive response (increased water clarity, increased SAV acreage) to model
simulated reductions in nitrogen, phosphorus, and sediment as observed in most other Bay tidal
fresh segments. For the reasons unique to that Bay segment. EPA would consider it to be in full
attainment of its shallow-water bay grass designated use if a 1 percent nonattainment level is
achieved.
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Chesapeake Bay TMDL
6.5.4 Explicit Margin of Safety for Sediment
In a TMDL, where there is uncertainty, an explicit MOS may be appropriate. In the Bay TMDL,
EPA determined that an explicit MOS is appropriate for sediment because the Bay Water Quality
Model was overly optimistic in its simulation of SAV acreages and water clarity attainment in
the shallows. Specifically, the Bay Water Quality Model projected that widespread attainment of
the SAV/water clarity standards would result at the current (2009) basinwide loading levels of
about 8 billion pounds per year. In contrast, however, recent data from the Baywide SAV aerial
survey and shallow-water quality monitoring data showed that most Bay segments were not
attaining the SAV restoration acreages goals or water clarity criteria. That discrepancy justified
the need for an explicit MOS to ensure that the sediment allocations would achieve the Bay
jurisdictions' SAV/water clarity WQS.
EPA acknowledges that the science supporting the estuarine modeling simulation of the transport
and resuspension for sediment is not as strong as that for nitrogen and phosphorus.1 It is
important to note, however, that many of the conservative assumptions identified in the implicit
MOS discussion for nitrogen and phosphorus in Section 6.2.4 also apply to the MOS for
sediment. In addition to the conservative assumptions in the modeling and allocation methods,
EPA applied an explicit MOS in establishing the sediment allocations.
Since the SAV/water clarity modeling methodology was overly optimistic, and because reducing
phosphorus often has the co-benefit of reducing sediment, EPA established sediment allocations on
the basis of sediment loads that EPA estimated would result from implementing the phosphorus
controls. The basin-jurisdiction sediment allocations initially were expressed as an allocation range
reflecting the application of an explicit MOS in order to provide the jurisdictions with some
flexibility in preparing their WIPs (USEPA 201 Oh). That initial allocation range was from 6.1
billion pounds per year to 6.7 billion pounds per year. Using 8 billion pounds per year of sediment
as the estimate of the load needed to generally attain at the Baywide SAV/water clarity standards,
that allocation range provides a Baywide range for MOS of about 16 to 24 percent.
In the final TMDL, EPA used a singular allocation to the basin-jurisdictions for sediment as
opposed to a range. The method used to interpret the WIPs to derive that allocation is described
in Section 8. The final Baywide sediment allocation is about 6.5 million pounds per year. So that
allocated load yields a Baywide explicit MOS of 19 percent. Of course, the explicit MOS for
each of the Bay segments would be expected to be somewhat higher or lower than the Baywide
MOS. It is EPA's professional opinion that an explicit Baywide MOS of 19 percent—which is
beyond the conservative assumptions identified in the Section 6.2.4 above on the implicit MOS
for nitrogen and phosphorus—is appropriate for establishing the sediment allocations.
6.6 Establishing the Basin-Jurisdiction Allocations for Sediment
The methodology used for allocating sediment loads to major river basins and jurisdictions for
sediment was much different than the methodology used for nitrogen and phosphorus. Because
sediment has a localized water quality effect, the immediate subbasin (e.g., the Chester River) is
1 Copies of the Chesapeake Bay Water Quality Sediment Transport Model Review Panel's (convened by the CBP's
Scientific and Technical Advisory Committee) reports are at
http://\vw\v.chesapeakebay.net/'committee_msc_projecis.aspx?nienuitem-l652?«peer.
6-44 December 29, 2010
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usually the dominant controlling influence on water clarity and SAV growth. Therefore, a
methodology is not needed to further suballocate the loading to contributing jurisdictions or
neighboring basins. On August 13, 2010, the EPA Region 3 Administrator sent a letter to the
jurisdictions identifying the sediment allocations (IJSFPA 2010g).
6.6.1 Methodology for Determining Sediment Allocations
To identify the sediment loads needed to achieve the SAV/water clarity WQS, the following key
steps were taken:
• Determine the sediment loading for each Bay segment that would be expected from
installing the controls needed to meet the phosphorus allocations but have the co-benefit of
reducing sediment (as described above).
• Using the Bay Water Quality Model, determine the number of acres in each segment that
would attain the clarity standards for that segment and divide that number by 2.5 to
determine the SAV equivalent acres.
• Add the SAV equivalent acres determined above to the expected SAV acreage on the basis
of observed acres to determine the total SAV acreage expected under that nitrogen,
phosphorus, and sediment loading scenario.
• Compare the expected SAV acres to the SAV goal for that segment to determine attainment
with the WQS.
• For the non-attaining segments, go back to step I.
Of the 92 tidal Bay segments assessed by Maryland, Virginia, Delaware, and the District of
Columbia, 26 achieve the respective jurisdiction's SAV/water clarity WQS according to
available monitoring data (Appendix P). Twenty segments have mapped SAV acreages meeting
the segment-specific SAV restoration acreage in the jurisdiction's WQS (single best year of the
past 3 years). Of the 12 water clarity acre assessments that were performed, an additional 6
segments were found to attain the jurisdiction's water clarity criteria on the basis of an analysis
of shallow-water monitoring data (Figure 6-17).
However, the Bay Water Quality Model projected widespread attainment at existing loading
levels, yet the existing SAV water quality data show SAV/water clarity WQS nonattainment in
66 of 92 segments with only 46 percent of the Bay-wide restoration acreage achieved
(Appendix P). The existing state of scientific understanding has resulted in the Bay Water
Quality Model being optimistic in its simulation of SAV acreage in the Bay under current (2009)
pollutant loads.
6.6.2 Addressing Water Clarity/SA V Nonattaining Segments
After applying the sediment loads described above, four segments were initially found to be in
nonattainment of the SAV-water clarity WQS. Those segments are the Mattawoman Creek
(MATTF). the Gunpowder River (GUNOH), the Appomattox River (APPTF), and the Virginia's
portion of the lower Potomac River (POTMH VA). A detailed assessment of those nonattaining
segments are in Appendix N, but a brief review is provided below.
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Chesapeake Bay TMOL
SAV or Water Clarity Attainment
m Attaining (SAV)
Attaining (Clanty Only)
• Not Attaining
Source* DC DOE 2008 DE DNREC 2008 MDE 2O08 VA DEQ 2008 Appendix Q
Figure 8-17. Chesapeake Bay SAV/Water Clarity WQS attainment from monitoring data assessment
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Chesapeake Bay TMDL
Mattawoman Creek (MATTF)—Recent aerial surveys have shown a remarkable recover)' of the
acreage of SAVs in the Mattawoman Creek. In fact, for the years 2006-2009 the acres of
.observed SAV was higher than the SAV goal. Furthermore, with the implementation of the
allocations in this TMDL, further nitrogen, phosphorus, and sediment reductions are expected,
which will likely encourage additional SAV growth. So from the observed SAV line of evidence,
EPA concludes that the allocated sediment load to Mattawoman Creek will attain the SAV goals.
Gunpowder River (GUNOH)—Similar to the Mattawoman Creek, substantial regrowth of SAV
has occurred in the Gunpowder River since 2000. While the SAV goal is not being exceeded
consistently, there have been several recent years where the goal is essentially met. On the basis
of observed SAV information, combined with the fact that the TMDL allocations will result in
additional nitrogen, phosphorous, and sediment reductions, EPA concludes that the allocated
sediment load to the Gunpowder River will attain the SAV goals.
Appomattox River (APPTF)
No reported SAV acres are in the Appomattox River in the recent record. Therefore, attainment in
this segment will need to be based on attainment for the clarity WQS alone. On the basis of
modeling results at the allocation levels, the clarity levels barely attain applicable WQS. So an
overall sediment allocations for the James may not be specific enough to assure attainment of the
SAV standards in the Appomattox River. Therefore, while the basin-jurisdiction allocation for
sediment for the James has been established, it is important to closely track the regrowth of SAV in
the segment and use that information to provide needed updates to the assessment for the segment.
Virginia's portion of the lower Potomac River (POTMH_VA)
This segment covers the embayments on the Virginia side of the lower tidal Potomac River. The
embayments are well isolated from the Potomac River and, therefore, respond primarily to the
inputs from the subwatershed and not the Potomac itself. Recent SAV observations for the
segment are much improved over the past but still far short of the WQS. Therefore, attainment
determinations for the segment rely largely on the clarity attainment. As a reminder, the
predicted SAV levels can be calculated as a combination of the measured SAV levels plus acres
of clarity attainment (divided by 2.5). If one uses the critical period 1993-1995 SAV observed
acreage and combines this acreage with the expected clarity attainment at the allocation loadings,
the segment does not attain the SAV goal at the sediment allocation level. Furthermore, at much
higher levels of controls (lower loadings), beyond the sediment allocation, the calculated
nonattainment for this segment persists. There is simply not enough shallow water habitat in the
segment to attain the standard on the basis of water clarity alone. On the other hand, all
neighboring Bay segments in the tidal Potomac River are expected to achieve the SAV standards
with the implementation of the sediment allocations. Therefore, having limited basis for which to
establish a sediment allocation, and in consideration that neighboring Bay segments are expected
to attain the SAV standards, EPA retained the sediment allocations for the Potomac basin.
However, EPA considers it important, similar to the Appomattox River, to closely track the
regrowth of SAV in this segment and use that information to provide needed updates to the
assessment for this segment.
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Ch«-sapejke Bay TMDL
6.7 Basin-Jurisdiction Allocations to Achieve the Bay WQS
()n (he basis of all the methods and analvses described above. EPA identified allocations for the
in.i|or basins within each jurisdiction called the basin-jurisdiction allocations. Those allocations
were the beginning point for developing the Ba> TMDl and are provided below.
6.7.1 Basin-Jurisdiction Allocations Tables
I hroughout 2009 up until the summer of 2010. FPA and its watershed jurisdictional partners
worked together to develop the major river basin jurisdiction allocations. From those
Lollahor-itivc efforts, 1 PA shared an initial set of major river basin jurisdiction nitrogen and
phosphorus target loads on November 3. 2009. on the basis of decisions at the October 23. 2009,
PSC meeting (I SI PA 200%). Then, after a 2-da> PSC meeting on April 29-30. 2010. EPA
shared in a letter to the partners an updated Ba> TMDL schedule and further outlined a long-term
Commitment to an adaptive management approach to the Ba> IMDL (t'SEPA 20100
I he basin-jurisdiction allocations were based on attaining the adopted (but proposed at the time)
amendments to the jurisdictions Ba> WQS On Jul> I. 2010. EPA shared the nitrogen and
phosphorus allocations (t iSEPA 20lOg) and the sediment allocations on August 13. 2010
(I SI PA 20IOh). 'I hose were the alligations that jurisdictions used to develop their Phase I WIPs
that further suhallocate the nitrogen, phosphorus, and sediment loadings to finer geographic
scales and to individual sources or aggregate source sectors and EPA used to evaluate those
\V IPs Bv initially expressing the sediment allocations as a range. EPA allowed the jurisdictions
some flexibility in developing their Phase I WIPs while assuring with confirmation Water
Quality Model runs that all the WQS would be met (Figure 6-18) (LSEPA 2010h). The
allocations were calculated as delivered loads (the loading that actually reaches tidal waters) and
as annual loads The loads are provided in Tables 6-7 and 6-8 The allocations were further
refined through the jurisdictions' WIPs by exchanges of loadings for some basins in Maryland
and exchanges of nitrogen to phosphorus or phosphorus to nitrogen within a basin. Those
adjusted allocations are provided in Section 8.
6.7.2 Correction of the West Virginia Sediment Allocation
I he allocation tor sediment tor West Virginia, listed in Tables 6-7 and 6-8. was corrected
subsequent to the distribution of the sediment allocation letter to the jurisdictions on August 13.
2<»Ki Recall that the sediment range of allowable loads was based on the expected sediment
loading that would result as a co-benefit to reducing phosphorus So the sediment range was
highly dependent on the phosphorus allocation Phe reason the sediment allocation for West
Virginia needed to be corrected was that the previous sediment allocation in the EPA letter of
August I 3, 2010. was not based on the supplemental phosphorus load that was provided to West
Virginia When the full phosphorus allocation for West Virginia is considered, the updated
sediment load range lor West Virginia was 309 340 million of pounds per year For the Potomac
River in West Virginia, the updated sediment load range is 294-324 million pounds per year.
I he sediment allocation range for the James River Basin in West Virginia remains unchanged.
6-48 December 29, 2010
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Chesapeake Bay TMOL
Source USE PA 201 Oh
Figure 6-18. Model simulated sediment loads by scenario compared with the range of sediment allocation*
(billions of pounds per year as total suspended sediment).
6.8 Attainment of the District of Columbia pH Water Quality Standard
After the development of the nitrogen, phosphorus and sediment allocations to achieve the Ba\
DO, chlorophyll u. SAV/water clarity WQS, EPA conducted an analysis to explore whether
these allocations were sufficient to retried} the pH impairment in the District of Columbia
portion of the Potomac River Estuary. The upper Potomac River Estuary from Ke> Bridge to
Haines Point has been on the District of Columbia's 303(d) list of impaired waters for pH from
1998 to present. EPA believes that the high pH levels are indirect Iv caused b\ the relationship
between high nitrogen and phosphorus levels and algal growth. Readilv available nitrogen and
phosphorus in surface waters supports the growth of algae, which can become prolific when
nitrogen and phosphorus levels are high. During photosynthesis, algae use carbon dioxide,
resulting in high pH conditions (Sawyer et al. 1994). In water, carbon dioxide gas dissolves to
form soluble carbon dioxide, which reacts with water to form undissociated carbonic acid.
Carbonic acid then dissociates and equilibrates as bicarbonate and carbonate. Generallv, as
carbon dioxide is used up in photosynthesis, pH rises because of the removal of carbonic acid
(Home and Goldman 1994). It is expected that the high pH levels in this segment of the tidal
Potomac River are due to primary productivity (algal growth). Algal growth is fueled bv excess
nitrogen and phosphorus inputs. On the basis of a reasonable degree of scientific certaintv. as
further explained below, EPA finds that the reduced nitrogen and phosphorus loads resulting
from implementation of the Chesapeake Bay TMDL will also result in decreased algae levels
and, thus, meet the District of Columbia pH numeric WQS.
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December 29, 2010
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Chesapeake Bay TMDL
Table 6-7. Chesapeake Bay watershed nitrogen and phosphorus and sediment allocations by
major river basin by jurisdiction to achieve the Chesapeake Bay WQS
Basin
Susquehanna
Eastern Shore
Western Shore
Patuxent
Potomac
Rappahannock
York
James
Jurisdiction
New York
Pennsylvania
Maryland
Total
Delaware
Maryland
Pennsylvania
Virginia
Total
Maryland
Pennsylvania
Total
Maryland
Total
Pennsylvania
Maryland
District of Columbia
Virginia
West Virginia
Total
Virqinia
Total
Virginia
Total
Virqinia
West Virginia
Total
Total Basin/Jurisdiction Allocation
Atmospheric Deposition Allocation3
Total Basinwide Allocation
Nitrogen
allocations
(million
Ibs/year)
8.48°
71.74
1.08
81.31"
2.95
9.71
0.28
1.21
14.15
9.74
0.02
9.76
2.85
2.85
4.72
15.70
2.32
17.46
4.67
44.88
5.84
5.84
5.41
5.41
23.48
0.02
23.50
187,69
15.70
203.39
Phosphorus
allocations
(million
Ibs/year)
0.62"
2.31
0.05
2.98°
0.26
1.09
0.01
0.16
1.53
0.46
0.001
0.46
0.21
0.21
0.42
0.90
0.12
1.47
0.74
3.66
0.90
0.90
0.54
0.54
2.34
0.01
2.35
12.62
-
12.62
Sediment
allocations
(million
Ibs/year)
293-322
1,660-1,826
60-66
2,013-2,214
58-64
166-182
21-23
11-12
256-281
155-170
0.37-0.41
155-171
82-90
82-90
221-243
654-719
10-11
810-891
294-324 c
1,989-2,1 88 c
681-750
681-750
107-118
107-118
837-920
15-17
852-937
6,135-6,749
-
6,135-6,749
a. Cap on atmospheric deposition loads direct to Chesapeake Bay and tidal tributary surface waters to be achieved
by federal air regulations through 2020.
b. This allocation to New York does include the additional (beyond the draft) allocation of 250,000 pounds per year of
nitrogen and 100,000 pounds per year of phosphorus that EPA added to the New York allocation (see Section 6.4.5)
c. This allocation includes a correction of the sediment allocations to West Virginia to account for the increase in
phosphorus allocation provided to West Virginia (see Section 6.7.2)
To support that assumption, continuous monitoring data from the District of Columbia's
Department of the Environment long-term monitoring station at the Roosevelt Island Bridge
were evaluated. This location falls within the impaired tidal Potomac River segment
(POTTF_DC) and is the only location for which continuous data are available for trend analysis.
Plots of pH vs. chlorophyll a for the period of record indicate a distinct relationship between the
two parameters; increased chlorophyll a levels are associated with increased levels of pH. That
relationship is particularly apparent for April through June of 2010 (Figure 6-19).
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December 29, 2010
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Chesapeake Bay TMDL
Table 6-8. Chesapeake Bay watershed nitrogen and phosphorus and sediment allocations by
jurisdiction by major river basin to achieve the Chesapeake Bay WQS
Jurisdiction
Pennsylvania
Maryland
Virginia
District of Columbia
New York
Delaware
West Virginia
Basin
Susquehanna
Potomac
Eastern Shore
Western Shore
PA Total
Susquehanna
Eastern Shore
Western Shore
Patuxent
Potomac
MD Total
Eastern Shore
Potomac
Rappahannock
York
James
VA Total
Potomac
DC Total
Susquehanna
NY Total
Eastern Shore
DE Total
Potomac
James
WV Total
Total Basin/Jurisdiction Allocation
Atmospheric Deposition Allocation3
Total Basinwide Allocation
Nitrogen
allocations
(million Ibs/year)
71.74
4.72
0.28
0.02
76.77
1.08
9.71
9.74
2.85
15.70
39.09
1.21
17.46
5.84
5.41
23.48
53.40
2.32
2.32
8.48 b
8.48"
2.95
2.95
4.67
0.02
4.68 .
187.69
15.70
203.39
Phosphorus
allocations
(million
Ibs/year)
2.31
0.42
0.01
0.001
2.74
0.05
1.09
0.46
0.21
0.90
2.72
0.16
1.47
0.90
0.54
2.34
5.41
0.12
0.12
0.62"
0.62"
0.26
0.26
0.74
0.01
0.75
12.62
-
12.62
Sediment
allocations
(million Ibs/year)
1,660-1,826
221-243
21-23
0.37-0.41
1,903-2,093
60-66
166-182
155-170
82-90
654-719
1,116-1,228
11-12
810-891
681-750
107-118
837-920
2,446-2,691
10-11
10-11
293-322
293-322
58-64
58-64
294-324 c
15-17
309-341 c
6,135-6,749
-
6,135-6,749
a. Cap on atmospheric deposition loads direct to Chesapeake Bay and tidal tributary surface waters to be achieved
by federal air regulations through 2020.
b. This allocation to New York does include the additional (beyond the draft) allocation of 250,000 pounds per year of
nitrogen and 100,000 pounds per year of phosphorus that EPA added to the New York allocation (see Section 6.4.5)
c. This allocation includes a correction of the sediment allocations to West Virginia to account for the increase in
phosphorus allocation provided to West Virginia (see Section 6.7.2)
For the most recent 2-year period (September 2008 to November 2010), pH levels at that
location have regularly exceeded the maximum criterion level of 8.5; however, they never
exceeded 9.O.2 Those pH levels are similar to those observed at other tidal Potomac River
Estuary monitoring stations.
; In 9VAC25-260-50, Virginia requires that estuarine waters fall within the acceptable pH range of 6.0 to 9.0.
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December 29, 2010
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Chesapeake Bay TMDL
Chlorophyll a vs. pH (April through June)
Figure 6-19. District of Columbia's Roosevelt Island station pH versus chlorophyll a monitoring data
regression.
It is also important to note that no known wastewater discharges are expected to contribute to
high pH levels along this stretch of the Potomac. Only one nonsignificant industrial facility
discharges to the tidal Potomac River above this location, the Washington Aqueduct. Flow from
the facility is relatively small (13.2 million gallons per day) when compared to the tlow rate of
the Potomac (about 7 billion gallons per day) in the vicinity. Permit limits for the facility require
that pH is between 6.0 and 8.5. Examination of discharge monitoring report (DMR) data from
May 2003 to May 2010 for the facility indicates one pH violation on August 31, 2003, for pH of
9.22 at Outfall 004. No other outfalls had violations between May 2003 and February 2006, and
pH ranged from 6.5 to 8.0 during that time. A second violation, failure to report DMR data,
occurred in May 2010.3 A second facility, Walter Reed Army Medical Center, discharges
approximately 0.09 million gallons per day to the tidal Potomac River via Rock Creek. Because
of its upstream location, discharge characteristics (process water from heating and cooling
system and rooftop runoff), and small size, it is not a source of high pH waters. Because the next
segment upstream is the POTTF_MD, and it is not impaired for pH, no further upstream
discharge facilities were evaluated.
Flow and pH data for the most recent 2-year period show that high flows generally do not
correspond to pH exceedances. That evidence strongly suggests that nonpoint sources are not a
direct cause of the pH exceedances. For those reasons, it is EPA's best professional judgment
that pH exceedances are caused by the high nitrogen and phosphorus and resultant algae growth
and that the reductions expected to result from implementing the Chesapeake Bay TMDL will
also ensure attainment of the pH criterion in this segment of the Potomac.
3 EPA reviewed DMR records from both PCS and ICIS. Actual data were available from the PCS review (2003 to
early 2006), whereas the ICIS review (2006 to May 2010) provided information regarding whether a violation
occurred and the type of violation.
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Chesapeake Bay TMDL
The Washington Ship Channel is another waterbody segment in the District that was listed as
impaired on the District of Columbia's 1998 303(d) list and was part of EPA's Consent Decree.
In 2004 the District established, and EPA approved, a TMDL to address the pH impairment that
requires phosphorus reductions expressed in annual loads. Since the 2004 Washington Ship
Channel TMDL, the District's final 2008 303(d) list and its draft 2010 303(d) both indicate that
the Washington Ship Channel's aquatic life use is no longer impaired due to pH. It is EPA's best
professional judgment that this supports the conclusion that implementing the Chesapeake Bay
TMDL's nitrogen and phosphorus reductions will address the District of Columbia's pH
impairments and that implementing the Chesapeake Bay TMDL will continue to protect the
Washington Ship Channel from pH impairment. The Chesapeake Bay TMDL supersedes the
Washington Ship Channel's 2004 pH TMDL.
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Chesapeake Bay TMDL
SECTION 7. REASONABLE ASSURANCE AND
ACCOUNTABILITY FRAMEWORK
When the U.S. Environmental Protection Agency (EPA) establishes or approves a total
maximum daily load (TMDL) that allocates pollutant loads to both point and nonpoint sources, it
determines whether there is reasonable assurance that the load allocations (LAs) will be achieved
and water quality standards (WQS) will be attained. EPA does that to be sure that the wasteload
allocations (WLAs) and LAs established in the TMDL are not based on overly generous
assumptions regarding the amount of nonpoint source pollutant reductions that will occur.
This is necessary because the WLAs for point sources are determined, in part, on the basis of the
expected contributions to be made by nonpoint sources to the total pollutant reductions necessary
to achieve WQS. If the reductions embodied in LAs are not fully achieved because of a failure to
fully implement needed nonpoint source pollution controls, or that the reduction potential of the
proposed best management practices (BMPs) was overestimated, the collective reductions from
all sources will not result in attainment of WQS. As a result, EPA evaluates whether a TMDL
provides reasonable assurance that nonpoint source controls will achieve expected load
reductions.
For the Chesapeake Bay TMDL, numerous elements combine to provide that reasonable
assurance, of which the primary mechanism is the Accountability Framework described in
Section 7.2. Section 8 also describes EPA actions designed to provide additional assurance that
the Bay TMDL's allocations are achieved.
7.1 REASONABLE ASSURANCE
The Clean Water Act (CWA) section 303(d) requires that a TMDL be "established at a level
necessary to implement the applicable water quality standard." Federal regulations define a
TMDL as "the sum of the individual WLAs for point sources and LAs for nonpoint sources and
natural background" [40 CFR 130.2(i)]. Documenting adequate reasonable assurance increases
the probability that regulatory and voluntary mechanisms will be applied such that the pollution
reduction levels specified in the TMDL are achieved and, therefore, applicable WQS are
attained.
When a TMDL is developed for waters impaired by point sources only, the existence of the
National Pollutant Discharge Elimination System (NPDES) regulatory program and the issuance
of an NPDES permit provide the reasonable assurance that the WLAs in the TMDL will be
achieved. That is because federal regulations implementing the CWA require that effluent limits
in permits be consistent with "the assumptions and requirements of any available [WLA]" in an
approved TMDL [40 CFR l22.44(d)(l)(vii)(B)].
Where a TMDL is developed for waters impaired by both point and nonpoint sources, in EPA's
best professional judgment, determinations of reasonable assurance that the TMDL's LAs will be
achieved could include whether practices capable of reducing the specified pollutant load: (I)
exist; (2) are technically feasible at a level required to meet allocations: and (3) have a high
likelihood of implementation. Where there is a demonstration that nonpoint source load
7-1 December 29, 2010
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Chesapeake Bay TMDL
reductions can and will be achieved, a TMDL writer can determine that reasonable assurance
exists and, on the basis of that reasonable assurance, allocate greater loadings to point sources.
Without a demonstration of reasonable assurance that relied-upon nonpoint source reductions
will occur, the Bay TMDL would have to assign commensurate reductions to the point sources.
7.1.1 Overview of the Accountability Framework
For the Chesapeake Bay TMDL, reasonable assurance that nonpoint source load reductions will
be achieved is based, in large part, on the new accountability framework EPA is developing for
this TMDL, including the Bay jurisdictions' watershed implementation plans (WIPs). This
framework incorporates an adaptive management approach that documents implementation
actions, assesses progress, and determines the need for alternative management measures based
on the feedback of the accountability framework. As discussed below and in the Strategy for
Protecting ami Restoring the Chesapeake Bay Watershed (FLCCB 2010). the goal for installing
all controls necessary to achieve the Bay's DO. water clarity, SAV, and chlorophyll a criteria is
2025. F,PA therefore is making its evaluation of reasonable assurance according to that time
horizon. EPA has provided an interim goal that 60 percent of the reductions to achieve applicable
WOS occur by no later than 2017. This interim goal ensures that the large portions of necessary
reductions, or the more difficult restoration actions, are not left until the later years of the
restoration schedule.
Since 2008, EPA Region 3 has communicated its heightened expectations for reasonable
assurance in the Chesapeake Bay watershed and its basis for expecting the jurisdictions' WIPs to
assist in the demonstration of that reasonable assurance. EPA's September 11, 2008, and
November 4, 2009, letters and its April 2, 2010, Guide for EPA 's Evaluation of Phase I
Watershed Implementation Plans provide extensive information on what EPA expects the
jurisdictions to include in their WIPs to help demonstrate reasonable assurance (USEPA 2008b,
2009c, 2010e), including that the jurisdictions
• Develop WIPs that identify how point and nonpoint sources will reduce nitrogen,
phosphorus, and sediment loads sufficient to meet WQS for DO, chlorophyll a, SAV, and
water clarity in the tidal waters of the Chesapeake Bay and its tidal tributaries
• Commit to set and meet specific 2-year milestones for implementing practices to achieve
load reductions
EPA also has stated its intention to take additional federal actions, as determined to be
appropriate to ensure implementation of the Bay TMDL, as described in Section 7.2.4 below.
One of those potential federal actions is the modification or replacement of the TMDL. Another
is the use of EPA's discretionary authority to increase oversight of NPDES permits proposed and
issued by the Bay watershed jurisdictions. As discussed in EPA's December 29. 2009, letter,
pursuant to EPA-jurisdiction NPDES program agreements, EPA can expand its oversight review
of draft permits in the Bay watershed and can object to permits that do not meet CWA
requirements, including NPDES effluent limits that are inconsistent with the Bay TMDL's
WLAs (USEPA 2009d). EPA also could use its discretionary residual designation authority to
increase the number of sources, operations, or communities regulated under the NPDES permit
program.
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Chesapeake BayTMDL
As part of EPA's demonstration of reasonable assurance. EPA evaluated the jurisdictions' final
Phase I WIPs to determine whether the jurisdictions both met their target allocations and
provided sufficient reasonable assurance. Section 8 describes the results of EPA's evaluation of
the jurisdictions" final Phase I WIPs. Section 8 also describes EPA actions designed to provide
additional reasonable assurance that applicable WQS in the Chesapeake Bay watershed will be
attained and maintained.
In addition to the new Bay-specific accountability framework, reasonable assurance for the
Chesapeake Bay TMDL is based on the existence and implementation of numerous existing
federal, state, and local programs that provide for both point and nonpoint source controls. While
not all these programs provide funding or apply to all sources, together they contribute to EPA's
determination that reasonable assurance exists for the Chesapeake Bay TMDL.
7.1.2 Federal Strategy
President Obama signed Executive Order 13508 on May 12, 2009. That order directs federal
agencies to "define environmental goals for the Chesapeake Bay and describe milestones for
making progress toward attainment of these goals." The federal agencies fulfilled this order by
drafting the Strategy for Protecting and Restoring the Chesapeake Bay Watershed, which
focused on achieving four essential priorities to restore and maintain a healthy Chesapeake
ecosystem: restore clean water; recover habitat; sustain fish and wildlife; and conserve land and
increase public access (FLCCB 2010). The Federal Strategy articulates 12 key environmental
outcomes that will be achieved through federal actions and ongoing state activities. The
commitments and actions described in the Federal Strategy and annual federal action plans are a
unique and powerful tool to achieve the Bay's water quality goals and provide additional support
for reasonable assurance in this TMDL.
The Bay TMDL, along with the jurisdictions" WIPs, are key elements of the strategy because
together they provide a set of numeric pollutant reduction targets and implementation plans to
guide and assist achievement of the goal to restore clean water. Under the Federal Strategy, EPA
is also creating a system to track and report TMDL/W1P reduction goals and 2-year milestones
for federal and state agencies (see Section 7.2.3). The tracking system provides additional
reasonable assurance that the TMDL's allocations will be met by clearly charting ongoing
progress and. if there are shortfalls, informing EPA. the seven Bay watershed jurisdictions, and
other stakeholders, including the public, about the need for additional state and federal actions.
USGS, NOAA, and other federal agencies will work with EPA and the jurisdictions to improve
the water quality monitoring and tracking of management actions and restoration activities. Part
of that effort includes expanding and improving the NOAA Chesapeake Bay Interpretive Buoy
System and improving the monitoring of tidal river and upland stream conditions. Many other
federal agencies will undertake actions to conserve land, sustain fish and wildlife, and recover
habitat.
The strategy also outlines specific tools to promote transparency and accountability in the
implementation and coordination of the activities. Those tools include federal 2-year milestones
where the federal agencies identify and track their actions toward meeting water quality
milestones and other strategy outcomes. Other tools outlined in the strategy include an annual
7-3 December 29, 2010
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Chesapeake Bay TMDL
federal action plan, an annual progress report and providing for an independent evaluation of
both federal and state progress on meeting the goals set forth in section 206 of the Executive
Order.
7.1.3 Funding
The C'WA authorizes EPA to provide funding to the Bay watershed jurisdictions through various
sources, including but not limited to Chesapeake Bay Implementation grants, Nonpoint Source
C'ontrol grants, CWA section 106 grants for water pollution control programs, the Clean Water
State Revolving Loan Fund, the American Recovery and Reinvestment Act. and various grant
programs targeting Chesapeake Bay restoration. The funding will help the jurisdictions meet
their pollutant reduction targets.
In addition, significant U.S. Department of Agriculture (USDA) funds and cost share programs
are available through the Farm Bill, which recently were increased through the Chesapeake Bay
Watershed Initiative. USDA administers the funds and target priority watersheds in the
Chesapeake Bay. The Federal Strategy describes how USDA is working with producers to apply
new, more effective conservation practices on the highest priority watersheds in the Chesapeake
Bay basin. Along with an increase in federal cost share dollars. USDA is bringing an
unprecedented focus on targeted efforts in the watersheds that contribute the greatest reductions
in nitrogen, phosphorus, and sediment. That will substantially help the jurisdictions to meet their
respective LAs in the TMDL, to implement their WIPs. and to achieve their 2-year milestones
(FLCCB 2010 pp. 34-45). USDA also is leading efforts to accelerate development of new
conservation technologies and is contributing to the system of accountability for tracking and
reporting conservation practices. Finally, USDA is working to streamline conservation planning
and is sponsoring a number of showcase projects to test and monitor the benefits of a focused
outreach on a number of small watersheds (30,000-40,000 acres).
7.1.4 Air Emission Reductions.
The reasonable assurance for the reductions in loadings from air deposition is based on the air
emission reductions that will occur by regulation under the Clean Air Act (CAA) through 2020.
These reductions are discussed in more detail in Section 6.4.1 and Appendix L.
While the federal Bay strategy and associated activities are not a federal TMDL implementation
plan and are not directly part of the TMDL. the additional resources, accountability, oversight,
and coordination provided by EPA and other federal agencies add to the reasonable assurance
that the TMDL allocations will be implemented. Those combined elements, together with the
accountability framework described in greater detail below, collectively provide reasonable
assurance that the Chesapeake Bay TMDL nitrogen, phosphorus, and sediment allocations will
be achieved.
7.2 ACCOUNTABILITY FRAMEWORK
The C'hesapeake Bay Protection and Restoration Executive Order 13508 directs EPA and other
federal agencies to build a new accountability framework that guides water quality restoration of
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Chesapeake Bay TMDL
the Chesapeake Bay. In addition to the federal components described above as set forth in the
Federal Strategy, the Chesapeake Bay TMDL accountability framework has four elements:
• The Bay jurisdictions' development of WIPs;
• The Bay jurisdictions' development of 2-year milestones to demonstrate restoration
progress;
• EPA's commitment to track and assess the jurisdictions' progress, by way of developing
and implementing a Chesapeake Bay TMDL Tracking and Accountability System
(BayTAS); and
• EPA's commitment to take appropriate federal actions if the jurisdictions fail to develop
sufficient WIPs, effectively implement their WIPs, or fulfill their 2-year milestones.
The accountability framework, including the jurisdictions' WIPs and 2-year milestones, will help
ensure implementation of the Chesapeake Bay TMDL but is not itself an approvable part of the
TMDL. In its September 11, 2008, letter to the CBP's PSC (USEPA 2008b), EPA outlined the
following expectations for each of the Bay watershed jurisdictions as part of the Bay TMDL
accountability framework:
1. Identify the controls needed to achieve the allocations identified in the Bay TMDL
through revised tributary strategies.
2. Identify the current state and local capacity to achieve the needed controls (i.e., an
assessment of current funding programs for point source permitting/treatment upgrades
and nonpoint source controls, programmatic capacity, regulations, legislative authorities).
3. Identify the gaps in current programs that must be filled to achieve the needed controls
(i.e., additional incentives, state or local regulatory programs, market-based tools,
technical or financial assistance, new legislative authorities).
4. A commitment from each jurisdiction to work to systematically fill the identified gaps.
As part of this commitment, the jurisdictions would agree to meet specific, iterative, and
short-term (1-2 year) milestones demonstrating increased levels of implementation or
nitrogen, phosphorus, and sediment load reduction.
5. A commitment to continue efforts underway to expand monitoring, tracking, and
reporting directed to assessing the effectiveness of implementation actions and to use the
data to drive adaptive decision making and redirect management actions.
6. Agreement that if the jurisdictions do not meet the commitments, additional measures
might be necessary.
Letters sent by EPA to the jurisdictions on November 4, 2009, and December 29,2009, further
developed this accountability framework (USEPA 2009c, 2009d). In his July 1, 2010, and
August 13, 2010, letters to the jurisdictions setting out the draft nitrogen, phosphorus, and
sediment allocations, Regional Administrator Shawn Garvin further communicated key aspects
of the accountability framework (USEPA 2010g, 2010h).
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Chesapeake Bay TMDL
7.2.1 Watershed Implementation Plans
A major clement of FPA's demonstration of reasonable assurance for the Chesapeake Bay
TMDI. is the development of WIPs by each of the seven Bay watershed jurisdictions. The WIPs
have informed, and will continue to inform. EPA's development of the Bay TMDL and its
setting of WLAs and I.As. In essence, the WIPs are the roadmap for how the jurisdictions, in
partnership with federal and local governments, will achieve and maintain the Chesapeake Bay
TMDL nitrogen, phosphorus, and sediment allocations.
l-PA's November 4, 2009, letter outlined expectations for the WIPs. including that they address
the eight elements summari/ed in fable 7-1 below.
Table 7-1. Eight elements of the jurisdictions' Watershed Implementation Plans
Element
1 Interim and Final Nitrogen,
Phosphorus, and
Sediment Target Loads
2 Current Loading Baseline
and Program Capacity
3 Account for Growth
4 Gap Analysis
5 Commitment and Strategy
to Fill Gaps
6 Tracking and Reporting
Protocols
7 Contingencies for Slow or
Incomplete
Implementation
8 Appendix with Detailed
Targets and Schedule
Description
WIPs are expected to subdivide interim and final target loads by
pollutant source sector within each of the 92 areas draining to section
303(d) tidal water segments and identify the amount and location of
loads from individual or aggregate point sources and nonpoint source
sectors
WIPs are expected to include evaluation of current legal, regulatory,
programmatic, financial, staffing, and technical capacity to deliver the
target loads established in the TMDL.
WIPs are expected to describe procedures for estimating additional
loads due to growth and to provide EPA with information to inform
additional pollutant load reductions that are at least sufficient to offset
the growth and development that is anticipated in the watershed
between 201 1 and 2025
WIPs are expected to identify gaps between current capacity (Element
2) and the capacity needed to fully attain the interim and final nitrogen,
phosphorus, and sediment target loads for each of the 92 drainage
areas for impaired segments of the Bay TMDL (Element 1).
WIPs are expected to include a proposed strategy to systematically fill
the gaps identified in Element 4.
WIPs are expected to describe efforts underway or planned to improve
transparent and consistent monitoring, tracking, reporting, and
assessment of the effectiveness of implementation actions.
If the proposed strategies outlined in Element 5 are not implemented,
WIPs are expected to provide for alternative measures resulting in
equivalent reductions and an indication of what such contingencies
might entail
WIPs are expected to include detailed interim and final load targets for
each tidal Bay segment drainage area, source sector, and local area
(after November 201 1) in an appendix, with a reduction schedule
comprising the 2-year target loads at the scale of each major basin
within a jurisdiction
The 2-year target loads allow EPA to assess whether future 2-year
milestones are on schedule to meet interim and final water quality goals.
Source USEPA 2009c
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Chesapeake Bay TMDL
Three Phases of Watershed Implementation Plans
The jurisdictions are expected to develop WIPs over three Phases. Draft Phase 1 WIPs were
developed and submitted to EPA on or around September 1. 2010. EPA used them to support the
development of specific allocations in the draft Bay TMDL. Draft Phase I WIPs for each of the
seven Chesapeake watershed jurisdictions are at w w w .epa.go\ chesapeakeba\ tindl.
The jurisdictions submitted their final Phase 1 WIPs to EPA on November 29. 2010 (December
3, 2010 for Maryland: December 17. 2010 for New York; Pennsylvania amended December 23.
2010). for consideration in the final Bay TMDL. After working with local partners, the
jurisdictions are expected to submit their Phase II WIPs describing actions and controls to be
implemented by 2017 to achieve applicable WQS: deadlines for the submission of draft and final
Phase II WIPs to EPA are currently June I, 2011 and November 1. 2011. respectively, but these
dates will be revisited in early 2011. Finally, the jurisdictions are expected to submit to EPA by
2017. their Phase III WIPs describing refined actions and controls to be implemented between
2018 and 2025 to achieve applicable WQS.
With submission of the Phase II WIP. the jurisdictions are expected to subdivide the allocations
provided in the Bay TMDL at an increasingly finer scale (Table 7-2). During Phases II and III of
the WIP process, EPA will consider whether modifications to the Chesapeake Bay TMDL are
necessary and appropriate on the basis of developments or changes in the jurisdictions" WIPs
Table 7-2. Comparison of elements within the Chesapeake Bay TMDL and Phase I, II, and
III WIPs
Element
Individual or Aggregate WLAs and LAs to
Tidal Jurisdictions
Gross WLAs and LAs for Non-Tidal
Jurisdictions if those Jurisdictions Submit
WIPs that meet EPA Expectations
WLAs for individual significant point
sources, or, where appropriate,
aggregate point sources
LAs for nonpoint source sectors
Proposed actions and, to the extent
possible, specific controls to achieve
point source and nonpoint source target
loads
Point source and nonpoint source loads
by local area
Specific controls and practices to be
implemented by 201 7
Refined point source and nonpoint source
loads
Specific controls and practices to be
implemented by 2025
Bay TMDL
S
^
Phase I WIP
^
^
^
To the extent
possible
Phase II WIP
V
S
/
^
^
>/
V
V
Source: USEPA 2009c
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Chesapeake Bay TMDL
Evaluation of Phase I Watershed Implementation Plans
EPA provided the jurisdictions with a Guide for EPA 's Evaluation of Phase I Watershed
Implementation Plans in April 2010 detailing how it would evaluate the adequacy of the
jurisdictions' WIPs (USEPA 2010e). EPA also provided continuous feedback and technical
support to each jurisdiction on elements of its final Phase 1 WIP that the jurisdiction submitted
informally to EPA.
Upon receiving the jurisdictions' final Phase I WIPs, EPA evaluated the WIPs to determine
whether they met EPA's expectations as described in the April 2010 guide and in EPA's
November 4, 2009, letter (USEPA 2009c, 2010e). EPA's WIP evaluation process involved a
systematic review of the contents of the eight elements of each jurisdiction's final Phase I WIP
(see Section 8).
The final Phase I WIPs were to include the Bay jurisdictions' proposed allocations to sources
and sectors and a demonstration of reasonable assurance that those proposed allocations will be
achieved and maintained. The Chesapeake Bay TMDL incorporates the jurisdictions' proposed
allocations where they enable the jurisdictions to meet the overall loadings necessary to meet
applicable WQS and where the jurisdictions provided sufficient reasonable assurance.
Where the proposed allocations provided by a jurisdiction in its final Phase I WIP did not meet
the overall loadings necessary to meet applicable WQS or where the jurisdiction provided an
insufficient demonstration of reasonable assurance, EPA established alternative WLAs and LAs
and provided additional reasonable assurance as appropriate, (see Section 7.2.4 and Section 8)
(USEPA 2009d).
7.2.2 Two- Year Milestones
EPA will measure the jurisdictions' progress toward reaching the TMDL's ultimate nitrogen,
phosphorus, and sediment reduction goals against 2-year milestones by which the jurisdictions
are expected to identify and commit to implement specific pollutant-reduction controls and
actions in each of their successive 2-year milestone periods (USEPA 2009c). The federal
government also will be providing 2-year milestones.
Before the start of each milestone period, EPA will evaluate whether the 2-year commitments are
sufficient to achieve necessary reductions identified in the jurisdictions' WIPs for the associated
2-year milestone period and whether the jurisdictions have fulfilled their previous milestone
commitments. As discussed in Section 7.1, an independent evaluation will be made of progress
toward achieving the water quality restoration goal in accordance with section 206 of the
Executive Order.
When assessing 2-year milestone commitments, EPA will evaluate whether proposed actions,
controls, and practices would result in estimated loads at the jurisdiction scale that meet the
jurisdiction's 2-year milestone targets (USEPA 2009c). If EPA determines that a jurisdiction
would not achieve the milestone loads identified, EPA may identify which source sectors, basins,
and local areas would not achieve reductions on schedule to meet that jurisdiction's interim and
final target loads. EPA will then be in a position to decide what appropriate action to take (see
Section 7.2.4) (USEPA 2009d).
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Chesapeake Bay TMDL
At the end of a milestone period, EPA expects that model-estimated nitrogen, phosphorus, and
sediment loads resulting from reported implementation would be at or below target loads at the
jurisdiction scale (Figure 7-1). Note that the 2009 load represented in Figure 7-1 includes
nitrogen delivered to the Bay from atmospheric deposition on the watershed. EPA estimates that
delivered nitrogen loads will be reduced by 3.4 million pounds by 2025 through implementation
of rules and standards under the CAA. The graph in Figure 7-1 does not include the 17.4 million
pounds of atmospheric nitrogen deposited directly to tidal waters of the Bay, of which
approximately 1.7 million pounds per year will be reduced by 2025 through implementation of
rules and standards under the CAA.
Basinwide Interim Target Load
275
EPA Will
Assess If
Milestone
Reductions
are on
Schedule to
Meet Target 51
Loads S
i 225
200
175
150
117
2009
2011
2013
2015
2017
2019
2021
2023
2025
Assumes Upfront Program-Building and Future Reductions
Assumes Constant Reduction Over Time
Assumes Upfront Low-Hanging Fruit and More Difficult Future Reductions
Source: USEPA 2009c
Figure 7-1. Relationship between WIPs and 2-year milestones.
In comparison to past Bay restoration efforts, the WIPs and 2-year milestones are expected to
provide greater specificity regarding source sector and geographic load reduction, more rigorous
assurances that load reductions will be achieved, and more detailed and transparent reporting to
the public (USEPA 2008b, 2009c, 201 Of).
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Chesapeake Bay TMDL
7.2.3 Chesapeake Bay TMDL Tracking and Accountability System
To determine whether sufficient progress is being made toward meeting the TMDL allocations
and interim milestones, EPA will rely on the jurisdictions to monitor, verify, and report their
progress. EPA will use the reported tracking data and the Phase 5.3 Chesapeake Bay Watershed
Model along with Chesapeake Bay tidal and watershed water quality monitoring data (including
contributions from other federal agencies including NOAA, USGS. USAGE, and L'SDA) to
assess the jurisdictions' progress.
While the jurisdictions will continue to report annually to EPA on BMP and other pollution
control implementations within their respective jurisdiction, existing tracking and reporting
mechanisms must be enhanced to fully measure progress toward meeting the TMDL allocations.
As EPA stated in its December 29, 2009, letter, where jurisdictions do not provide verification
that reported practices and controls have been properly installed and maintained, EPA may not
fully or partially credit these actions in its assessment of annual progress and 2-year milestones
(USEPA 2009d).
EPA will track the jurisdictions' progress toward achieving the gap-filling strategies proposed in
their WIPs through their 2-year milestone commitments using a transparent Chesapeake Bay
TMDL Tracking and Accountability System (BayTAS). EPA is designing BayTAS in
consultation with the jurisdictions.
BayTAS is a Web-based system that uses data from EPA and the jurisdictions to
• Track the WLAs and LAs established in the TMDL. Tracking entails storing the loadings
values and managing changes in status that may occur to the loadings in the future;
• Enable users to determine progress toward the final TMDL allocations, using progress run
data from the Chesapeake Bay Watershed Model;
• Track progress relative to the milestones identified by jurisdictions in their WIPs; and
• Record the baseline nitrogen and phosphorus and sediment control practices reported in the
Bay jurisdictions' WIPs and track progress against those baselines.
Executive Order 13508 called for developing such a tracking and accountability system. In
addition, implementation of the system is a commitment of EPA under the May 12, 2010,
Settlement Agreement between Chesapeake Bay Foundation and EPA. under which EPA
committed to begin implementation of a tracking system 30 days after establishment of the final
TMDL.
Version 1.0 of BayTAS (and future upgrades) will provide EPA, the Bay watershed jurisdictions,
and the public with information about LAs and WLAs established in the Chesapeake Bay
TMDL, and the jurisdictions" respective progress toward implementing the strategies outlined in
their Phase I WIPs.
EPA expects to refine and adjust BayTAS as the jurisdictions submit their Phase II and Phase III
WIPs. As it is refined, BayTAS is expected to enable higher levels of monitoring of jurisdiction
pollution-control programs than currently exist, including tracking the implementation of WLAs
in NPDES permits; LAs for nonpoint sources; offsets of new or increased loadings of nitrogen,
phosphorus, and sediment; and pollutant trades.
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Chesapeake Bay TMDL
One critical system that will facilitate the exchange of information between the jurisdictions and
the Bay Watershed Model is the National Environmental Information Exchange Network
(NEIEN).1 NEIEN is a partnership among the jurisdictions and EPA that facilitates exchange of
environmental information. Partners in the NEIEN share data efficiently and securely over the
Internet.
The jurisdictions have received EPA resources to develop NEIEN schema for reporting nitrogen.
phosphorus, and sediment controls on sources other than wastewater treatment plants and began
to submit annual implementation data to the Chesapeake Bay Program using the NEIEN format
after October 2010 (USEPA 2010b). As the WIP development and evaluation process proceeds,
EPA expects that the data-sharing relationships and practices among the jurisdictions and EPA
will rely heavily on NEIEN to support the BayTAS. In fact. BMPs may be incorporated into
BayTAS only if they are reported through NEIEN.
BayTAS data also will come from different EPA and national systems. Basic facility/permit
information will come from EPA's Permit Compliance System (PCS) or the Integrated
Compliance Information System (ICIS); DMR data and other information forNPDES permits
will be submitted by the jurisdictions as part of an existing grant agreement; BMP
implementation status information will come from the National Environmental Information
Exchange Network (NEIEN); and the status of loadings information will come from the
Chesapeake Bay Watershed Model. As other processes are implemented. BayTAS may
incorporate information from additional data sources.
Once BayTAS Version 1.0 becomes operational 30 days from establishment of the TMDL. data
flow into BayTAS will be electronic (e.g., via NEIEN) or loaded by the BayTAS operation and
maintenance team. This will eliminate the jurisdictions' data entry and other operational
requirements for maintaining the system. As noted above. Ba\ jurisdictions are expected to
review information in BayTAS to ensure accuracy and for other needs and to advise the Bay IAS
team on design over the lifecycle of the system.
7.2.4 Federal EPA Actions
In its December 29, 2009, letter to the jurisdictions, EPA listed various federal actions that EPA
may take if a jurisdiction fails to demonstrate progress toward meeting required nitrogen,
phosphorus, and sediment load reductions (USEPA 2009d). EPA may take action if a jurisdiction
fails to do the following:
• Develop and submit Phase I, II, and HI WIPs consistent with the expectations and schedule
described in EPA's letter of November 4, 2009, and the amended schedule described in
EPA's letter of June 11,2010
• Develop 2-year milestones consistent with the expectations, load reductions, and schedule
described in EPA's letter of November 4, 2009. and the amended schedule described in
EPA's letter of June 11,2010
hUP: \v\v\v.eDa.gov Networks info index.htmI.
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Chesapeake Bay TMDL
• Achieve each successive set of 2-year milestones and their respective target loads by
having appropriate controls in place pursuant to the strategies identified in the jurisdiction's
WIP and 2-year milestones
• Develop and propose sufficiently protective NPDES permits consistent with the CWA and
the Chesapeake Bay TMDL WLAs
• Develop appropriate mechanisms to ensure that nonpoint source LAs are achieved
Following is the list of potential actions EPA may take to ensure that jurisdictions develop and
implement appropriate WIPs, attain appropriate 2-year milestones of progress, and provide
timely and complete information to an effective accountability system for monitoring pollutant
reductions:
• Expand NPDES permit coverage to unregulated sources: For example, using residual
designation authority to increase the number of sources, operations or communities
regulated under the NPDES permit program
• NPDES program agreements: Expanding EPA oversight review of draft permits
(significant and nonsignificant) in the Bay watershed and objecting to inadequate permits
that do not meet the requirements of the CWA (including NPDES effluent limits that are
not consistent with the Chesapeake Bay TMDL WLAs)
• Require net improvement offsets: For new or increased loadings, requiring net
improvement offsets that do more than merely replace the anticipated new or increased
loadings
• Establish finer-scale WLAs and LAs in the Chesapeake Bay TMDL: Establishing more
specific allocations in the final December 2010 Chesapeake Bay TMDL than those
proposed by the jurisdictions in their Phase I WIPs
• Require additional reductions of loadings from point sources: Revising the final December
2010 Chesapeake Bay TMDL to reallocate additional load reductions from nonpoint to
point sources of nitrogen, phosphorus, and sediment pollution, such as wastewater
treatment plants
• Increase and target federal enforcement and compliance assurance in the watershed: That
could include both air and water sources of nitrogen, phosphorus, and sediment
• Condition or redirect EPA grants: Conditioning or redirecting federal grants; incorporating
criteria into future Requests for Proposals based on demonstrated progress in meeting WIPs
or in an effort to yield higher nitrogen, phosphorus, or sediment load reductions
• Federal promulgation of local nutrient WQS: Initiating promulgation of federal standards
where the jurisdiction's WQS do not contain criteria that protect designated uses locally or
downstream
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Chesapeake BayTMDL
SECTION 8. WATERSHED IMPLEMENTATION PLAN
EVALUATION AND RESULTANT
ALLOCATIONS
This section describes the process by which EPA established final basinw ide and basin-
jurisdiction allocations to replace the target allocations described in Section 6. This section
specifically describes the methodology that EPA used to evaluate the jurisdictions' final Phase I
WIPs. the results of EPA's evaluation of the final Phase 1 WIPs. the process EPA used to
develop the final allocations, and the resultant final allocations. Segment-specific and sector-
specific allocations are provided in Section 9. Links to each jurisdiction's final Phase I WIP are
at vNww.epa.gov'chesapeakebaytmdl.
The overall process of developing the Chesapeake Bay TMDL had four steps:
1. EPA defined 19 major river basin and jurisdictional target allocations, which EPA
communicated to the jurisdictions on July 1, 2010 (for nitrogen and phosphorus) and
August 13, 2010 (for sediment). The methodology that EPA used in setting these target
allocations is described in detail in Section 6.
2. Each jurisdiction developed a Phase I WIP that described how it would achieve the target
allocations for nitrogen, phosphorus, and sediment that were assigned in Step 1.
a. Using data submitted by the jurisdictions as input decks, or spreadsheets that EPA
processed through Chesapeake Bay Program's Scenario Builder and the Phase 5.3
Chesapeake Bay Watershed Model, each jurisdiction developed suballocations to
assign to individual, significant wastewater treatment plant (WWTP) point
sources; aggregate nonsignificant WWTPs, urban stormwater. and CAFO point
sources; and nonpoint source sectors draining to each of the 92 segments of the
Chesapeake Bay and its tidal tributaries.
b. Each jurisdiction also developed implementation strategies to achieve the
suballocations, as EPA requested in its letters of September 11, 2008, November
4, 2009, and December 29, 2009. as well as the Guide for EPA 's Evaluation of
Phase I Watershed Implementation Plans issued April 2. 2010. Those
expectations are further described in Section 7.
c. The jurisdiction's proposed suballocations and implementation strategies formed
the basis of its final Phase I WIP, which the jurisdiction delivered to EPA on
November 29, 2010 (December 3. 2010. for Maryland; December 17. 2010. for
New York; Pennsylvania amended December 23. 2010).
3. EPA evaluated each jurisdiction's proposed suballocations and implementation strategies in
its final Phase I WIP to determine whether the WIP met the jurisdiction-wide and major
river basin allocations, included adequate detail to ensure that NPDES permits will be
developed that are consistent with the assumptions and requirements of the WLAs. and met
EPA's expectations of providing reasonable assurance that nonpoint source reductions
would be achieved and maintained through credible and enforceable or otherw ise binding
strategies in jurisdictions that are signatories to the Chesapeake Bay Agreement, and
8-1 December 29, 2010
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Chesapeake Bay TMDL
similarly effective strategies in non-signatory jurisdictions. That evaluation and its results
are described in detail here in Section 8.
4. On the basis of the results of EPA's evaluation of all seven Bay jurisdictions' final Phase I
WIPs and refinements EPA made thereto, and supplemented by more than 14,000
comments from the public during a formal public review of the draft TMDL, EPA
established an allocation scenario for the final Chesapeake Bay TMDL. This allocation
scenario includes allocations at the jurisdiction-wide and basin-wide levels, as wejl as
allocations for each of the 92 Bay segments. Tables showing the segment-specific and
sector-specific allocations of the Chesapeake Bay TMDL are in Section 9.
EPA is establishing in this Chesapeake Bay TMDL final allocations that are based on the
jurisdictions' final Phase I WIPs wherever possible and supplemented by public comments.
Overall, the final Phase I WIPs were significantly improved from the draft Phase I WIPs, with
most jurisdictions meeting their target allocations and meeting EPA's expectations of reasonable
assurance that those target allocations would be met. These improved Phase I WIPs are a direct
result of the cooperative work and leadership by the jurisdictions, each of which worked closely
with EPA over the past few months to strengthen its WIP. As a result of these improvements in
the jurisdictions' final Phase I WIPs, EPA significantly reduced the backstop allocations that had
been proposed in the draft TMDL for most of the jurisdictions, and, in some cases, completely
removed the backstops. As explained in detail in Section 8.4 below, only New York,
Pennsylvania, and West Virginia received allocations that differed from those proposed in their
final Phase I WIPs.
Six of the seven jurisdictions met their jurisdiction-wide target allocations for nitrogen,
phosphorus, and sediment. In the one jurisdiction that did not fully meet its target allocations
(New York), the final TMDL established a backstop allocation in the form of additional
reductions from wastewater treatment loads beyond those proposed by New York in its final
Phase I WIP to meet the jurisdiction-wide and basinwide TMDL allocations.
In addition, five of the seven jurisdictions met EPA's expectations of reasonable assurance in
their final Phase I WIPs that they would achieve the load reductions proposed in their final Phase
I WIPs. In jurisdictions that did not meet EPA's expectations that the necessary reductions for a
particular source sector would be achieved (Pennsylvania urban stormwater, West Virginia
agriculture), the final TMDL established backstop adjustments to the sector allocations that
shifted a portion of the proposed LA to the WLA in that particular sector. This allocation
adjustment recognizes the jurisdictions' already substantial pollutant reduction commitments and
signals that future regulatory and/or permitting actions may need to be implemented to achieve
the necessary load reductions. This allocation adjustment also provides an additional measure of
reasonable assurance that these reductions will be achieved, yet does so in a manner that affords
the jurisdictions an appropriate measure of flexibility to decide exactly how the final allocations
will be achieved.
EPA will track progress and take any additional federal actions that are necessary to ensure that
these reductions are achieved and maintained. To further ensure that the Bay TMDL is
supported by reasonable assurance, EPA is committing to enhanced oversight actions in those
jurisdictions whose final Phase I WIP did not fully meet EPA's expectations. As a result of this
enhanced oversight, EPA will evaluate, on an ongoing basis, the need for appropriate future
8-2 December 29, 2010
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Chesapeake Bay TMDL
backstop actions and is committed to taking actions consistent with its December 29, 2009, letter
as necessary; such necessity may be demonstrated if, for example, the jurisdictions do not
demonstrate sufficient progress in the wastevvater. urban stormvvater, or agriculture sectors in
their Phase II WIPs (USEPA 201 Od). EPA also is committed to maintaining its ongoing
oversight in all seven of the Chesapeake Bay jurisdictions as authorized under the CWA, and, in
conjunction with its accountability and tracking system and the series of two-year milestones, is
committed to taking additional appropriate federal action consistent with its December 29, 2009,
letter to ensure that the jurisdictions successfully implement their TMDL allocations and final
Phase I WIPs.
8.1 WIP EVALUATION METHODOLOGY
A team of EPA source sector experts, together with the EPA staff assigned to each of the seven
watershed jurisdictions, conducted a rigorous, systematic quantitative and qualitative evaluation
of each jurisdiction's final Phase I WIP and accompanying input deck. EPA evaluated each final
Phase I WIP on the basis of how well the jurisdiction's final Phase I WIP was designed to
achieve WQS and meet the TMDL's target allocations. EPA evaluated the final Phase I WIP in
light of the expectations articulated in EPA's November 4, 2009 letter and April 2, 2010, Guide
for Evaluation of Phase I Watershed Implementation Plans (USEPA 2009c, 20lOe). EPA also
considered whether the jurisdiction addressed key areas for improvement that EPA identified as
a result of its review of the jurisdiction's draft Phase I WIP.
In conducting the evaluations, EPA addressed two primary questions:
(I) Whether the jurisdiction met its target allocations for nitrogen, phosphorus, and
sediment—both jurisdiction-wide and in each of the major river basins—to ensure attainment of
each of the Chesapeake Bay WQS in all 92 segments of the Bay and its tidal tributaries; and
(2) Whether the jurisdiction met EPA's expectations for reasonable assurance that it
would implement the necessary nitrogen, phosphorus, and sediment reductions, including
documentation that nonpoint source controls would be achieved and maintained and permitting
programs would result in point source reductions, with emphasis on having practices in place by
2017 to achieve at least 60 percent of the necessary reductions as compared to 2009 loads.
8.1.1 Quantitative Evaluation of the Final Phase I WIPs
To evaluate the first (quantitative) question and determine whether a jurisdiction met each of its
nitrogen and phosphorus target allocations, EPA processed the jurisdiction's input deck by
running it through Scenario Builder and the Chesapeake Bay Watershed Model, assuming that
other jurisdictions met their target allocations. If the jurisdiction's WIP exceeded any of the
target allocations, EPA considered the degree to which it did so and whether adjusting nitrogen
and phosphorus allocations using approved ratios as discussed in Section 6 would decrease the
exceedances.
EPA determined each jurisdiction's allocation for sediment on the basis of whether and to what
extent the jurisdiction met the target allocation range for sediment provided on August 13, 2010
and any modifications that EPA approved as still meeting applicable WQS. EPA ran the BMPs
8-3 December 29, 2010
-------
Chesapeake Bay TMDL
assumed within the nitrogen and phosphorus backstop allocations through Scenario Builder and
the Chesapeake Bay Program Watershed Model. EPA then compared the sediment outputs from
that scenario run to the target allocation range for sediment that it communicated to the
jurisdictions. Where the reductions proposed in a jurisdiction's W1P surpassed what was needed
to meet the target allocation (i.e., came in under the low end of the target range), EPA assigned
that jurisdiction the low end of the target allocation range. Where the reductions proposed in a
jurisdiction's WIP were insufficient to meet its target allocation (i.e., came in above the high end
of the target range), EPA assigned that jurisdiction the high end of the target allocation range.
Where a jurisdiction met its target allocation (i.e., fell within the target range), EPA assigned that
jurisdiction the allocation that resulted from the practices proposed in its final Phase 1 WIP.
8.1.2 Qualitative Evaluation of the Final Phase I WIPs
To evaluate the second (qualitative) question and determine whether a jurisdiction met EPA's
expectations for reasonable assurance through enforceable or otherwise binding commitments or
similarly effective strategies to implement necessary controls, EPA evaluated each major
pollutant source sector (agriculture, urban stormwater, and wastewater) on a number of criteria,
including those factors set out in the April 2, 2010, Guide for Evaluation oj Phase I Watershed
Implementation Plans (USEPA 20lOe). EPA determined that a jurisdiction met EPA's
expectations for reasonable assurance if it provided, among other things: a schedule for potential
actions, evidence of or commitment to clear permit conditions, a discussion of compliance, no
major discrepancies between the type and extent of practices in the WIP narrative and the input
deck, contingencies for high risk or highly improbable actions, and proposals for obtaining
additional resources..
After evaluating the two key questions, EPA conducted ajurisdiction-by-jurisdiction analysis to
determine whether and, if so, to what degree, to backstop or adjust the allocations proposed by
the jurisdiction in its final Phase I WIP. In developing the adjusted or backstop allocations, EPA
fully considered the following:
• Whether a jurisdiction met, or to what degree it missed, its target allocations for nitrogen,
phosphorus, and sediment.
• Whether and to what extent the jurisdiction met EPA's expectations for reasonable
assurance.
• Whether the proposed WLAs in the jurisdiction's final Phase I WIP were consistent with
EPA's definition of point source loads and could be achieved through implementation of a
permitting program.
• Whether, if necessary, EPA could ensure achievement of the point source reductions
through appropriate federal actions under the CWA and other federal authorities, including
enhanced program oversight, permit objections, compliance assurance, enforcement
actions, and other federal actions as described in EPA's December 29, 2009 letter.
Where EPA determined that a jurisdiction did not meet its target allocations, EPA applied a
backstop allocation—a change to the allocation to close the numeric gap, such as assigning the
jurisdiction a more stringent WWTP allocation reflecting an assumption that future WWTP
8-4 December 29, 2010
-------
Chesapeake Bay TMDL
effluent limits for nitrogen and/or phosphorus would be made more stringent to meet the
TMDL's overall allocation for that jurisdiction.
Where EPA determined that a jurisdiction met its allocation target but did not meet EPA's
expectations for reasonable assurance, EPA applied a backstop adjustment or allocation
adjustment—a change to a sector-specific allocation to provide additional assurance that the
allocation would be achieved, such as shifting some of a specific sector's loadings from the LA
category to the WLA category. This signaled that, depending on the success of the jurisdiction's
WIP implementation and the nature of the choices the jurisdiction makes in adapting its
implementation strategies, additional future regulatory controls may have to be applied to
sources in that sector to attain the sector's overall allocation.
If EPA had determined that a jurisdiction neither met its target allocation nor met EPA's
expectations for reasonable assurance, EPA would have applied both backstops.
After applying all backstops that EPA determined were necessary, EPA ran the combination of
specific practices and allocations through the Chesapeake Bay Program's Scenario Builder and
the Phase 5.3 Chesapeake Bay Watershed Model to ensure that the allocations provided in the
final Chesapeake Bay TMDL would result in the attainment of WQS.
8.2 WIP EVALUATION RESULTS
Overall, the jurisdictions submitted significantly-improved final Phase I WIPs; most jurisdictions
met each of their target allocations jurisdiction-wide and met EPA's expectations for reasonable
assurance that they would meet those target allocations. Six of the seven jurisdictions met or
came very close to their jurisdiction-wide target allocations for nitrogen, phosphorus, and
sediment—only New York did not meet each of its jurisdiction-wide target allocations. In
addition, five of the seven jurisdictions met EPA's expectations for reasonable assurance in their
final Phase I WIPs that they would achieve the load reductions proposed in their WIPs. Only
Pennsylvania urban stormwater and West Virginia agriculture did not meet EPA's expectations
for providing reasonable assurance that the sector-specific target allocations would be achieved.
These are significant improvements from the draft Phase 1 WIPs, where six of the seven draft
WIPs did not meet their jurisdiction-wide target allocations for all three pollutants and none of
the seven draft WIPs fully met EPA's expectations for reasonable assurance that they would
meet their respective target allocations.
8.2.1 Target Allocation A ttainment
Each jurisdiction's final Phase I WIP, with the exception of New York, met its jurisdiction-wide
nitrogen, phosphorus, and sediment target allocations. EPA established backstop allocations for
WWTP allocations in New York to close the numeric gap between New York's final Phase I
WIP and its target allocations.
The results of EPA's analysis of whether each jurisdiction met its jurisdiction-wide and basin-
wide target allocations for each pollutant after allowing for any EPA-approved exchanges are
shown in Tables 8-1 and 8-2, below. Table 8-1 shows whether and to what degree each
jurisdiction met its jurisdiction-wide target allocations for nitrogen, phosphorus, and sediment.
8-5 December 29, 2010
-------
Table 8-1. Comparison between nitrogen, phosphorus, and sediment jurisdiction-wide allocations and final Phase I
Watershed Implementation Plans, in millions of pounds per year
00
r>
n>
3
cr
n>
•^
NJ
U3
DC
DE
MD"
NY°
PA
VAd
WV*
Total
Total nitrogen (TN)
Target
allocation
2.32
2.95
39.09
(39.09)
8.77
(8.23)
73.93
(76.77)
53.42
(53.40)
5.45
(4.68)
185.93
(187.45)
Final Phase
IWTP
2.32
2.86
39.09
9.25
75.56
54.43
5.45
188.96
Final Phase
1 WIP % off
target
0%
-3%
0%
5%
2%
2%
0%
2%
Total phosphorus (TP)
Target
allocation
0.12
0.26
2.72
(2.72)
0.57
(0.52)
2.93
(2.74)
5.36
(5.41)
0.59
(0.75)
12.54
(12.52)
Final Phase
I WIP
0.12
0.23
2.72
0.57
2.98
5.48
0.59
12.70
Final Phase
1 WIP % off
target
0%
-12%
0%
2%
2%
2%
-1%
1%
Total suspended solids (TSS)*
Target
allocation -
low
10.14
57.82
1,116.16
292.96
1,902.51
2,446.14
309.37
(240.68)
6,135.10
(6066.42)
Target
allocation -
high
11.16
63.61
1,218.11
(1,227.78)
322.26
2,092.76
2,690.75
340.30
(264.75)
6,738.94
(6673.06)
Final Phase
IWIP
11.16
42.89
1,218.11
277.66
1 ,979.65
2,617.22
302.12
6448.80
Final Phase
1 WIP % off
target*
0%
-33%
0%
-14%
-5%
-3%
-11%
-4%
O
(D
8
3
01
fi
CO
ffi
As discussed in Section 6, the metric for sediment is Total Suspended Solids.
a. Calculated on the basis of the high end of the target sediment allocation range.
b. Maryland target allocations were modified to allow for exchanges of TN, TP, and TSS both within and across basins. Runs of the Chesapeake Bay Water
Quality and Sediment Transport Model confirmed that these exchanges still attained applicable WQS. The original target allocations are in parentheses. The
final allocations proposed in Maryland's final Phase IWIP are derived using the method outlined in Appendix A of Maryland's final Phase IWIP rather than an
input deck that was run through the Chesapeake Bay Program Watershed Model.
c. New York's nitrogen and phosphorus target allocations were modified to provide New York with additional loads of TN (1,000,000 Ibs) and TP (100,000 Ibs)
based on concerns with the equity of New York's July 1 target allocations (see Section 6.4.5). Target nitrogen and phosphorus allocations were further modified
to allow, for trading of TN and TP within state basins. The original target allocations are in parentheses.
d. Virginia target allocations were modified to allow for trading TN and TP within state basins. The original target allocations are in parentheses.
e. West Virginia Potomac basin target allocations for nitrogen and phosphorus were revised to allow for trading between TN and TP, and the sediment target
allocation range was adjusted based on the 200,000 Ib increase in the July 1st phosphorus allocation (see Section 6.4.5). The original target allocations are in
parentheses.
f. Where input decks in West Virginia, Virginia, and Pennsylvania did not meet all target allocations, EPA and the jurisdiction came to an agreement on how to
dose the gap. See Section 8.4 for details regarding these agreements.
g. In New York, EPA closed the gap via an adjustment to nitrogen and phosphorus allocations using approved ratios as discussed in Section 6 and via a backstop
allocation for the wastewater sector as described in Section 8.4.4.
Note: Any discrepancy is due to the rounding of figures.
-------
Table 8-2. Comparison between the nitrogen, phosphorus, and sediment basin-jurisdiction allocations and final Phase I
Watershed Implementation Plans, in million pounds per year
Major river
basin
Potomac
Eastern Shore
Eastern Shore
Patuxent
Potomac
Susquehanna
Western Shore
Susquehanna
Eastern Shore
Potomac
Susquehanna
Western Shore
Eastern Shore
James
Potomac
Rappahannock
York
James
Juris-
diction
DC
DE
MD"
MDb
MDb
MDb
MDb
NY0
PA
PA
PA
PA
VAd
VA"
VAd
VA
VA
WV
Total nitrogen (TN)
Target
allocation
2.32
2.95
9.71
2.86
(2.85)
16.38
(15.70)
1.09
(1.08)
9.04
(9.74)
8.77
(8.23)
0.28
4.72
68.90
(71.74)
0.02
1.31
(1.21)
23.09
(23.48)
17.77
(17.46)
5.84
5.41
0.02
(0.02)
Final
Phase 1
WIP
2.32
2.86
9.71
2.86
16.38
1.09
9.04
9.25
0.28
4.17
71.10
0.002
1.35
23.09
18.24
6.15
5.61
0.03
Final Phase
I WIP % off
target
0%
-3%
0%
0%
0%
0%
0%
5%
-1%g
-12%
3%
-92%
3%
0%
3%
5%
4%
50%
Total phosphorus (TP)
Target
ALLOCATI
ON
0.12
0.26
1.02
(1.09)
0.24
(0.21)
0.90
0.05
0.51
(0.46)
0.57
(0.52)
0.01
0.42
2.49
(2.31)
0.001
0.14
(0.16)
2.37
(2.34)
1.41
(1.47)
0.90
0.54
0.01
(0.01)
Final
Phase 1
WIP
0.12
0.23
1.02
0.24
0.90
0.05
0.51
0.57
0.01
0.35
2.62
0.0002
0,14
2.43
1.41
0.94
0.56
0.01
Final Phase
1 WIP % off
target
0%
-12%
0%
0%
0%
0%
0%
2%9
-13%9
-17%
5%
-76%
0%
3%
0%
5%
4%
18%B
Total suspended solids (TSS)*
Target
allocation -
low end
10.14
57.82
165.88
81.93
653.61
59.85
154.90
292.96
21.14
221.11
1659.89
0.37
10.91
836.57
810.07
681.49
107.09
15.13
Target
allocation -
high end
11.16
63.61
168.85
(182.47)
106.30
(90.12)
680.29
(718.97)
62.84
(65.83)
199.82
(170.38)
322.26
23.25
243.22
1,825.88
0.41
12.00
920.23
891.08
749.64
117.80
16.65
Final
Phase 1
WIP
11.16
42.89
168.85
106.30
680.29
62.84
199.82
277.66
19.11
219.12
1,741.17
0.26
11.31
948.49
829.53
700.04
127.86
29.35
Final Phase
1 WIP % off
target*
0%
-33%
0%
0%
0%
0%
0%
-14%
-18%
-10%
-5%
-37%
-6%
3%
-7%
-7%
9%
76%
o
(D
c/>
03
•D
O>
Q>
£
CO
00
D
ID
0
0)
3
cr
n>
•^
M
o
l-»
o
-------
Major river
basin
Potomac
TOTAL
Juris-
diction
WV8
ALL
Total nitrogen (TN)
Target
allocation
5.43
(4.67)
185.93
(187.45)
Final
Phase 1
WIP
5.43
188.96
Final Phase
1 WIP % off
target
0%
2%
Total phosphorus (TP)
Target
ALLOCATI
ON
0.58
(0.74)
12.55
(12.52)
Filial
Phase I
WIP
0.58
12.70
Final Phase
1 WIP % off
target
-1%
1%
Total suspended solids (TSS)*
Target
allocation -
low end
294.24
(225.55)
6,135.10
(6,066.42)
Target
allocation -
high end
323.66
(248.11)
6,738.94
(6,673.06)
Final
Phase I
WIP
272.77
6,448.80
Final Phase
1 WIP % off
target"
-16%
-4%
o
3-
CD
CO
a
ID
0)
7\
CD
00
00
00
As discussed in Section 6, the metric for sediment is Total Suspended Solids.
a. Calculated on the basis of the high end of the target sediment allocation range.
b. Maryland target allocations were modified to allow for exchanges of TN, TP, and TSS both within and across basins. Runs of the Chesapeake Bay Water
Quality and Sediment Transport Model confirmed that these exchanges still attained applicable WQS. The original target allocations are in parentheses. The
final allocations proposed in Maryland's final Phase I WIP are derived using the method outlined in Appendix A of Maryland's final Phase I WIP rather than an
input deck that was run through the Chesapeake Bay Program Watershed Model.
c. New York's nitrogen and phosphorus target allocations were modified to provide New York with additional loads of TN (1,000,000 Ibs) and TP (100,000 Ibs)
based on concerns with the equity of New York's July 1 target allocations (see Section 6.4.5). Target nitrogen and phosphorus allocations were further modified
to allow for trading of TN and TP within state basins. The original target allocations are in parentheses.
d. Virginia target allocations were modified to allow for trading TN and TP within state basins. The original target allocations are in parentheses.
e. West Virginia Potomac basin target allocations for nitrogen and phosphorus were revised to allow for trading between TN and TP, and the sediment target
allocation range was adjusted based on the 200,000 Ib increase in the July 1st phosphorus allocation (see Section 6.4.5). The original target allocations are in
parentheses.
f. Where input decks in West Virginia, Virginia, and Pennsylvania did not meet all target allocations, EPA and the jurisdiction came to an agreement on how to
close the gap. See Section 8.4 for details regarding these agreements.
g. In New York, EPA dosed the gap via an adjustment to nitrogen and phosphorus allocations using approved ratios as discussed in Section 6 and via a backstop
allocation for the wastewater sector as described in Section 8.4.4.
Note: Any discrepancy is due to the rounding of figures.
o>
n
n>
a-
CD
NJ
O
-------
Chesapeake Bay TMDL
Table 8-2 shows whether and to what degree each jurisdiction met its basinwide target
allocations for nitrogen, phosphorus, and sediment.
These tables show the initial target allocations communicated to the jurisdictions on July 1. 2010
(for nitrogen and phosphorus) and August 13, 2010 (for sediment), which are in parentheses.
These tables also show the jurisdictions' adjusted target allocations, which incorporate corrections
to allocations for some of the headwater jurisdictions, backstop allocations and adjustments made
by EPA, and intra-basin and inter-basin nutrient exchanges requested by the some of the
jurisdictions. The combination of these corrections, backstop allocations and adjustments, and
nutrient exchanges resulted in all jurisdictions meeting their nitrogen, phosphorus, and sediment
target allocations. Further specific information about the corrections, backstop allocations and
adjustments, and nutrient exchanges is provided in the footnotes to the tables.
8.2.2 Reasonable Assurance
EPA determined that each of the jurisdictions' final Phase I WIPs provided reasonable assurance
that met EPA's expectations in each major source sector, with the exception of Pennsylvania
urban stormvvater and West Virginia agriculture. The jurisdictions' final Phase I WIPs showed
many noteworthy improvements regarding reasonable assurance, including the following:
• Commitments to upgrade WWTPs
• Expanded septic system improvements
• Increased accountability for urban stormwater programs
• New enforcement and compliance initiatives for agriculture
• Agreements to extend regulatory coverage for traditional nonpoint sources if needed
Overall, these are significant improvements from the jurisdictions' draft Phase I WIPs, none of
which provided reasonable assurance that fully met EPA's expectations.
EPA determined that various levels of EPA oversight and additional potential actions are
appropriate for the various jurisdictions as a result of EPA's evaluation of both key aspects of the
jurisdictions' final Phase I WIPs as discussed above. All seven jurisdictions will receive an
ongoing level of oversight for all sectors that may justify federal actions to address shortfalls. In
addition to that ongoing oversight, New York, Pennsylvania, Virginia, and West Virginia will
receive an enhanced level of oversight and potential federal actions for certain sectors. Lastly, in
addition to those levels of oversight and potential federal actions. New York, Pennsylvania, and
West Virginia received in the final TMDL backstop allocations (New York) or backstop
adjustments (Pennsylvania urban stormwater and West Virginia agriculture). Further details
regarding EPA's assessment of the reasonable assurance provided by each jurisdiction's final
Phase I WIP are provided in Section 8.4 below.
8.3 ALLOCATION METHODOLOGY
EPA determined each jurisdiction's wasteload and load allocations on the basis of whether the
jurisdiction met each of its respective target allocations and whether it met EPA's expectations
for reasonable assurance that those allocations would be achieved. EPA relied on the portion(s)
8-9 December 29, 2010
-------
Chesapeake Bay TMDL
of the jurisdiction's final Phase I \VIP that met expectations and supplemented any gaps in the
allocations and reasonable assurance with allocation adjustments and determinations of
reasonable assurance to achieve the necessary reductions.
8.3.1 Backstop Allocation Methodology
I PA established backstop allocations where EPA determined that the final Phase I WIP did not
achieve the jurisdiction's basin target allocation for one or more pollutants or where the final
Phase I WIP did not meet EPA's expectations for reasonable assurance that the LA reductions
\vould be achieved b\ the nonpoint sources.
Another enhanced action that EPA took in the nontidal jurisdictions of Pennsylvania and West
Virginia was to establish finer-scale individual allocations or aggregate allocations. EPA stated
in its November 4 and December 29. 2009. letters to the jurisdictions that it might do so by
establishing individual source and aegregate source sector, rather than gross basin-jurisdiction,
\VI.As and I. As for the nontidal jurisdictions if their Phase I WIPsdid not meet EPA's
expectations for reasonable assurance (I'SEPA 2009c, 2009d). With the exception of WWTPs in
New York and the James River in Virginia. EPA is establishing individual WLAs for the
significant municipal and industrial wastewater discharging facilities and sector-specific
aggregate WI.As for urban stormvvater. CAFOs. and nonsignificant municipal and industrial
wastewater discharging facilities. EPA is establishing the finer-scale allocations to better inform
permit writers as they issue and renew NPDES permits consistent with the assumptions and
requirements of the Chesapeake Bay TMDL WLAs. Those allocations for the nontidal
jurisdictions are at the same scale as those made to the tidal jurisdictions of Delaware. Maryland,
Virginia, and the District of Columbia.
As explained more fully in Appendix X. EPA is issuing with this final TMDL an aggregate
WLA for the significant facilities in the Virginia portion of the James River basin. EPA also is
establishing an aggregate WLA for WWTPs in New York to allow time for the New York State
Department of Environmental Conservation to review engineering reports from WWTPs and
determine the load reductions expected from each facility. New York has committed to provide
information to support individual WLAs for these WWTPs in its Phase II WIPs. EPA
understands that New York plans to renew and/or modify W WTP permits after completing its
Phase II WIPs, consistent with the applicable TMDL allocations at that time.
8.3.2 Backstop Adjustment (Allocation Shift) Methodology
After evaluating the final Phase I WIPs for reasonable assurance. EPA found that the final Phase
I WIPs did not fully meet EPA's expectations for reasonable assurance for the urban stormwater
sector in Pennsylvania and the agriculture sector in West Virginia. As a result, EPA applied a
backstop adjustment to those sectors by shifting a portion of the allocations for those sectors
from the LA to the WLA for the respective jurisdiction.
Eor Pennsylvania urban stormvvater. as detailed in Section 8.4.5 below. EPA shifted to the WLA
50 percent of the loading from currently unregulated urban stormwater sources that the WIP
included in the LA. Therefore, the Pennsylvania urban stormwater WLAs include both
unregulated and NPDES regulated sources. For urban stormwater sources already covered by
8-10 December 29, 2010
-------
Chesapeake Bay TMDL
NPDES permits, EPA has broad authority to ensure that the necessary controls are included to
implement the Bay TMDL.
For West Virginia agriculture, as detailed in Section 8.4.7 below, EPA shifted to the WLA 75
percent of currently unregulated AFOs that the WIP included in the LA. The same rationale
described above also applies to EPA's adjustment of allocations in the AFO/CAFO sector. For
those CAFO facilities already under NPDES permit coverage, EPA has broad authority to ensure
that the necessary controls are included to implement the Bay TMDL.
For both AFOs and urban stormwater point sources, the allocation shift signals that substantially
more of these discharges and operations could potentially be subject to NPDES permits as
necessary to protect water quality. These conditions could include additional nitrogen,
phosphorus, and sediment controls. These sources would only be subject to NPDES permits as
issued by the delegated permitting authority or EPA upon designation. It is important to note,
however, that EPA may also pursue designation activities based upon considerations other than
TMDL and WIP implementation.
EPA has adjusted these allocations on the basis of two assumptions: (1) a percentage of loading
from currently unregulated sources may have to be controlled under the NPDES permit program
through appropriate designation, rulemaking, and permit issuances; and (2) the aggregate
projected load reductions under the adjusted WLA (based on assumed NPDES effluent controls
consistent with the WLA) will result in reductions sufficient to meet the jurisdiction's
allocations.
In establishing allocations that shift from the LA to the WLA some urban stormwater and
AFO/CAFO sources not currently regulated by the NPDES permit program but that could
become NPDES-regulated facilities either through residual designation authority or other
mechanisms, EPA has acted consistent with EPA guidance, Establishing Total Maximum Daily
Loads (TMDL) Wasteload Allocations (WLAs) for Storm Water Sources and NPDES Permit
Requirements Based on Those WLAs, dated November 22, 2002 (USEPA 2002a) and as revised
November 12, 2010. EPA has authority to designate certain nonregulated urban stormwater
sources for regulation under the NPDES program. See section 402(p)(2)(E) and (6) and 40 CFR
122.26(a)(9)(i)(C)(D). EPA also has authority to designate AFOs as CAFOs as set forth in 40
CFR 122.23(c).
The inclusion of currently unregulated sources in the WLA does not, by itself, constitute a
designation or regulatory action to include such sources in the NPDES program; the source
would have to be designated for the source to come under the NPDES program, and the shift in
allocations in this TMDL is not an exercise of that designation authority. Instead, it reflects the
possibility that such designation may be necessary in the future if the jurisdictions do not
otherwise achieve their allocation targets. The TMDL is a watershed pollution budget, not a
regulatory determination to change a source's legal status. As with any NPDES permitting or
rulemaking decision, applying new controls or designations must be consistent with applicable
procedural and substantive requirements, including a recognition of state permitting primacy in
jurisdictions authorized to administer the NPDES program.
Furthermore, EPA's residual designation would not be intended to change the NPDES-
permitting authorized agency. That is, if EPA were to residually designate an AFO as a CAFO in
8-11 December 29, 2010
-------
Chesapeake Bay TMDL
an NPDES-delegated state, that CAFO would apply for a state CAR) permit, not a federal
CAFO permit, as would any other state facility so long as KPA does not take over the permit or
the permitting program.
Some jurisdictions, as described in the jurisdiction-specific subsections below, included in their
final Phase I WIPs the shift of a portion or all of the loading of current AI-O or urban stormwater
facilities not currently regulated under the NPDES permit program from the LA to an aggregate
WLA. Jurisdictions did this primarily to provide additional reasonable assurance that the
implementation of practices and reductions in pollutants would occur. By doing this, the
jurisdiction indicated that it is prepared to implement the necessary pollutant reductions in those
sectors. Like EPA's backstop adjustment, the WIP's inclusion of currently unregulated sources
in the WLA by itself does not constitute a designation or regulatory action to include such
sources in the NPDES program. The jurisdiction's WIP informs the TMDL. which is a watershed
plan, not a regulatory determination to change a source's legal status. As with any NPDES
permitting or rulemaking decision, applying new controls or designations must be consistent
with applicable procedural and substantive requirements.
EPA believes these load-shifting allocation adjustments, whether done by the jurisdictions or by
EPA, are a reasonable way of supplementing reasonable assurance that the allocation targets will
be met. These allocations signal that EPA and the jurisdictions will be tracking load reductions in
these sectors with a heightened degree of scrutiny and are prepared to take action to increase the
extent to which these loads are regulated as necessary. EPA is committed to ensure and track
implementation of actions necessary to reduce these sector loads by 2025 consistent with
Executive Order 13508 (FLCCB 2010). Additional assurance that these adjusted sector
allocations will be met is provided by the public commitments EPA has made in the Federal
Strategy and elsewhere, including the May 2010 settlement agreement resolving the Chesapeake
Bay Foundation lawsuit.
8.3.3 Assumptions Supporting the Allocations
EPA regulations require that NPDES permits be consistent with assumptions and requirements of
WLAs. See 40 CFR !22.44(d)(l)(vii)(B). This section summarizes the assumptions that are
incorporated into the Chesapeake Bay TMDL allocations.
EPA established WLAs and LAs based in part upon the overall assumption that certain nitrogen,
phosphorus, and sediment controls are implemented on a certain percentage of available land.
Over time, implementing nitrogen, phosphorus, and sediment controls could involve a
combination of (a) different practices; (b) implementation in different locations; or (c)
implementation at different implementation rates so long as an equivalent or greater reduction
occurs within the portion of the watershed draining to a particular tidal segment of the
Chesapeake Bay.
Appendix V includes the percent of available land or sources on which nitrogen, phosphorus, and
sediment controls are implemented (percent implementation) that is assumed within the WLAs
and LAs for sources other than WWTPs. The Appendix does not include a table for Maryland
because final allocations proposed in Maryland's final Phase I WIP are derived using the method
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Chesapeake Bay TMDL
outlined in Appendix A of Mary land's WIP rather than an input deck that was run through the
Phase 5.3 Chesapeake Bay Watershed Model.
EPA will continue to track and assess the jurisdictions' annual progress toward meeting the
commitments outlined in their respective final Phase I WIPs and 2-year milestone commitments.
As outlined in its December 29, 2009, letter to the jurisdictions, EPA may take additional federal
actions beyond those listed above as appropriate and consistent with applicable laws and
regulations, including the following: conditioning federal grants; promulgating nutrient WQS;
objecting to NPDES permits; and discounting pollutant reduction practices that do not meet EPA
verification expectations to ensure that the jurisdictions achieve the nitrogen, phosphorus, and
sediment reductions identified in their final Phase I WIPs and needed to meet the TMDL
allocations (USEPA 20()9d) (see Section 7.2.4). In correspondence directed individually to each
jurisdiction providing detailed feedback on EPA's evaluation of the final Phase I WIPs (see
Appendix B), EPA communicated its intent to consider taking additional federal actions as
necessary if EPA determines that the respective jurisdiction's Phase II WIP and 2-year
milestones do not meet EPA's expectations for providing reasonable assurance that
implementation will occur as described in their plans.
Nonpoint Sources
The jurisdictions' final Phase I WIPs provided the starting point for EPA's consideration and
development of final allocations. EPA assumed for purposes of its evaluation that jurisdictions
would implement the practices that will result in the same or greater nitrogen, phosphorus, and
sediment controls as provided in their final Phase I WIP scenario input decks and as evaluated by
the Chesapeake Bay Scenario Builder and Watershed Model. In the few jurisdictions where final
Phase I WIP input decks did not meet the target allocations for each major basin, EPA either
applied a backstop allocation to close the numeric gap (New York) or reached agreement with
the respective jurisdictions on further nonpoint source reductions to achieve allocations both
statewide and in each basin (Pennsylvania, Virginia, West Virginia). Details regarding these
backstop allocations and nonpoint source adjustments are provided in Section 8.4.
EPA will assess jurisdictions' progress toward meeting LAs through ongoing program oversight.
the Phase II and Phase III WIPs, and the 2-year milestones. EPA also will consider whether to
take appropriate federal actions, as detailed in its letter of December 29, 2009 to the jurisdictions,
to ensure that adequate progress is made toward achieving and maintaining the nonpoint source
load reductions.
Point Sources—Agriculture
In all jurisdictions, the CAFO WLA includes AFO production areas that are currently or
potentially regulated under jurisdictions' CAFO programs. The CAFO WLA assumes that these
production areas have 100 percent implementation of waste management, barnyard runoff
control, and mortality composting practices and that such practices are required as conditions of
CAFO permits. These practices are assumed to result in an approximately 80 percent decrease in
nutrient loads from production areas compared to a pre-BMP condition. The draft TMDL
assumed that all animals within the WLA receive feed management except cattle on small dairies
not currently subject to CAFO permits. By comparison, the CAFO WLA in the final TMDL
assumes feed management at rates and nutrient reduction levels proposed by the jurisdictions in
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Chesapeake Bay TMDL
their final Phase I WIPs. Many of the final Phase I WIPs reflected higher rates of feed
management than did the draft WIPs.
Jurisdictions can meet the WLA assumptions by (a) applying a different set of practices that are
shown to result in equivalent nitrogen, phosphorus, and sediment reductions, or (b) applying a
more aggressive performance standard on a smaller percentage of AFO production areas that will
result in the nitrogen, phosphorus, and sediment reductions called for within the WLA.
Point Sources—Urban Stormwater
The Chesapeake Bay TMDL allocations for urban stormwater are based on load reductions
proposed by jurisdictions in their final WIPs compared to a 2009 baseline. In the draft TMDL,
EPA assumed additional urban stormwater retrofits in the five jurisdictions that received a
proposed urban stormwater backstop allocation. In contrast, in the final TMDL. EPA is
establishing a backstop adjustment for urban stormwater only in one jurisdiction—Pennsylvania.
Further, EPA is not adjusting the urban stormwater load reductions that Pennsylvania proposed
in its final Phase I WIP. Specifically, EPA is not assuming additional retrofits. Rather. EPA is
establishing a backstop adjustment in Pennsylvania that shifts 50 percent of the unregulated
urban stormwater load to the WLA.
Table 8-3 summarizes the per-acre, edge-of-stream nitrogen, phosphorus, and sediment percent
reductions compared to 2009 based on urban stormwater WLAs by jurisdiction. EPA can also
provide information by county to those jurisdictions that wish to use it in developing permits.
NPDES permits issued to these jurisdictions and other regulatory mechanisms should achieve
these reductions, over multiple permit cycles as necessary but by no later than 2025—the date by
which the Chesapeake Executive Council has committed to have all practices in place necessary
to meet water quality goals in the Bay. Jurisdictions have the option of interpreting these
allocations as specific measurable requirements, e.g., performance standards or management
practices, or of putting the allocations in permits and requiring MS4 operators to develop an
implementation plan to achieve the allocation.
Table 8-3. Percent reductions in edge-of-stream loads to achieve urban stormwater WLAs
Jurisdiction
District of Columbia
Delaware
Maryland"
New York
Pennsylvania
Virginia
West Virginia
Per-acre edge-of-stream % changes in urban stormwater load
from a 2009 baseline*
Nitrogen
6.6%
14.3%
16.9%
11.4%
28.9%
16.4%
0%
Phosphorus
29.6%
18.3%
35.7%
0.0%
17.7%
20.8%
0%
Sediment
29.6%
23.7%
37.5%
0.0%
7.0%
32.5%
0%
* Edge-of-stream reductions assumed within the urban stormwater WLAs result from differences in BMP
implementation rates between 2009 and the final WIP submission.
** Maryland's assumed reductions are calculated as the difference between 2009 edge-of-stream loads and
Maryland's final edge-of-stream target loads for urban stormwater WLAs. Maryland derived its final loads using the
method outlined in Appendix A of Maryland's WIP
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December 29, 2010
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Appendix V includes the percent implementation for nitrogen, phosphorus, and sediment
controls that are assumed on urban land uses in 2009 and as proposed in the final Phase I W1P
input decks. With the exception of Maryland, edge-of-stream reductions assumed within urban
stormwater WLAs are the direct result of the differences in implementation rates between 2009
and the final Phase I WIP submission. However, jurisdictions can meet the WLAs by (a) applying
a different set of practices or performance standards that would result in equivalent nitrogen.
phosphorus, and sediment reductions, or (b) applying a more aggressive suite of practices or
performance standards to a smaller percentage of urban lands or urban stormwater discharges, so
long as the total nitrogen, phosphorus, and sediment reduction from urban discharges within the
WLA are equal to or greater than the reductions assumed within Table 8-3.
Point Sources—Wastewater
Federal regulations require that water quality based effluent limits in permits ensure (a)
attainment of applicable WQS; and (b) consistency with assumptions and requirements of the
TMDL WLAs [40 CFR 122.44(d)(l)(vii)(B)]. Therefore, permits are written with effluent limits
necessary to meet applicable WQS and/or consistent with the assumptions and requirements of
applicable WLAs. Where authorized and appropriate, such effluent limits may contain a
compliance schedule that requires compliance as soon as possible. In the instances where
implementation of the final TMDL WLAs for wastewater facilities is staged (e.g., in the James
River), permits are written with effluent limits necessary to meet applicable WQS and/or
consistent with the assumptions and requirements of applicable WLAs. In those instances as
well, where authorized and appropriate, such effluent limits may contain a compliance schedule
that requires compliance as soon as possible. The TMDL assumes that all controls will be in
place to meet WLAs by 2025. Therefore, any facilities with compliance schedules longer than
one year must include interim dates and milestones in their permit fact sheets with the time
between milestones not more that one year [40 CFR 122.47(a)(3)].
The WLAs for WWTPs are based on the loads summarized in Table 9-4 for the significant
WWTPs in the Chesapeake Bay watershed. Additional information on edge-of-stream discharges
from these facilities is provided in Appendices Qand R.
Appendices Q and R also include the WLAs and information on edge-of-stream discharges for
facilities that have been aggregated in the final TMDL. For facilities with discharges that are part
of an aggregate WLA or are covered by a general permit, the TMDL assumes that the permit
contains language to require the establishment of individual schedules for each facility to come
into compliance with their individual or aggregate WLAs. Also, for facilities included within an
aggregate WLA, the TMDL assumes that permitting authorities will provide justification in the
permit fact sheet that the limits assigned to the individual facility are included as part of the
aggregate TMDL WLAs. Due to lack of specific information, some nonsignificant discharges
covered under an aggregate WLA may be based on default assumptions regarding flow and
concentrations. These facilities should provide, at a minimum, nitrogen, phosphorus, and/or TSS
monitoring data with their next NPDES permit renewal application. Renewed NPDES permits
for these discharges will require monitoring to verify existing loads and to either (1) verify that
these loads do not contribute to any exceedance of the WLAs—individual or aggregate
(determination of no reasonable potential to contribute to an exceedance of local WQS and/or
Bay TMDL WLA); or (2) incorporate an effluent limit consistent with the local WQS and/or Bay
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Chesapeake Bay TMDL
TMDL WLA (where monitoring data shows reasonable potential to contribute to an exceedance
of local WQS and/or Bay TMDL WLA).
Table 8-4. EPA backstop allocations, adjustments, and actions based on assessment of
final Phase I WIPs
DC
DE
MD
NY
PA
VA
WV
Stormwater
Wastewater
Agriculture
Stormwater
Wastewater
Agriculture
Stormwater
Wastewater
Agriculture
Stormwater
Wastewater
Agriculture
Stormwater
Wastewater
Agriculture
Stormwater
Wastewater
Agriculture
Stormwater
Wastewater
No Backsto
Ongoing
Oversight and
Actions
_ -
mm^m
p Allocation
Enhanced
Oversight and
Actions
^^^^^^^^^^^
Possible future
backstop
adjustments
Individual
allocations;
Possible future
backstop
allocations
Possible future
backstop
adjustments
Possible future
backstop
adjustments
Backstop Allocations, Adjustments,
and/or Actions
Backstop
Adjustments and
Actions
Shift 50%
Stormwater from LA
to WLA
Shift 75% AFOs
from LA to WLA
Individual
allocations;
Possible future
backstop
allocations H
Backstop
Allocations and
Actions
Reduce wastewater
WLA to meet
statewide allocation
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8.4 ALLOCATIONS BY JURISDICTION
On the basis of EPA's evaluations of the three major pollution source sectors combined with
EPA's evaluations of whether the jurisdictions met their respective nitrogen, phosphorus, and
sediment target allocations as illustrated in Tables 8-1 and 8-2, EPA assigned final allocations
according to the assumptions detailed below for each of the seven watershed jurisdictions.
Because EPA determined that many of the jurisdictions' final Phase I WIPs met all target
allocations and/or met EPA's expectations for reasonable assurance, EPA reduced or eliminated
many of the backstop allocations that it had included for those jurisdictions in the September 24.
2010, draft Chesapeake Bay TMDL. where warranted. The allocations for each jurisdiction, and
the assumptions and rationale underlying those allocations, are described below.
8.4.1 Delaware
Delaware developed a final Phase I WIP input deck with nitrogen, phosphorus, and sediment
controls that achieved jurisdiction-wide allocations when run through the Watershed Model.
Delaware's final Phase I WIP also met EPA's expectations for reasonable assurance. As a result,
EPA based Delaware's final allocations entirely on Delaware's final Phase I WIP. Delaware's
final Phase I WIP shifts the urban stormwater load into the WEA. provides stronger agricultural
contingencies to enhance reasonable assurance that reduction targets will be met, and improves
WWTP performance levels to meet nitrogen allocations.
Delaware Allocations
Delaware meets its nitrogen, phosphorus, and sediment allocations in the final TMDL, based on
EPA's quantitative and qualitative evaluation of Delaware's final Phase I WIP. Delaware's WIP
input deck resulted in jurisdiction-wide loads that are 3 percent under nitrogen, 12 percent under
phosphorus, and 33 percent under sediment target allocations. Delaware has agreed to apply the
spare pounds back to the nonpoint source agriculture allocation and to refine the implementation
measures in its Phase II WIP. Delaware's Bay TMDL jurisdiction-wide allocations are nitrogen
2.95 million pounds per year (mpy); phosphorus 0.26 mpy; and sediment 57.82 mpy.
Delaware Agriculture
Delaware's final Phase I WIP showed significant improvements from its draft Phase I WIP in the
agriculture sector, including a strong contingency that "Delaware commits to review and
evaluate the pace and progress of agriculture BMP implementation at the end of 2013. If needed,
Delaware will enact new policy measures and explore mandatory BMP compliance options in a
timely manner to ensure that water quality commitments will be met." Delaware's final Phase 1
WIP also includes greater detail on funding coordination and the implementation of agriculture
BMPs. These improvements bolster reasonable assurance that agriculture allocations will be met.
EPA will maintain ongoing oversight of Delaware's agriculture sector to ensure these allocations
are achieved and maintained. Specifically, EPA will use its national review of CAFO State
Technical Standards in 2011 and beyond as an opportunity to identify any deficiencies in the
State Technical Standards for protecting water quality. Through its review of State Technical
Standards, EPA also will evaluate whether Delaware's phosphorus management program is
sufficient to address phosphorus imbalances and water quality concerns. If deficiencies are
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identified that are not addressed or the permit does not include other conditions to achieve
nitrogen and phosphorus reductions identified in the WIP, EPA may object to permits on the
basis that they are not protective of water quality.
Delaware Urban Stormwater
Delaware's final Phase I WIP also showed significant improvements in the urban stormwater
sector. The WIP used BMPs that address both urban stormwater quality and quantity. The WIP
also describes proposed regulatory revisions that, once adopted, will require redevelopment to
reduce effective imperviousness by 50 percent and will increase required treatment volume for
new development to the level of annualized runoff from the 1-year frequency storm event (about
2.7 inches of rainfall). The initial goal of these regulatory provisions would be to use runoff
reduction practices so that effective imperviousness is 0 percent. Delaware's final Phase I WIP
further provided detailed strategies to restrict turfgrass fertilizer and documented a variety of
funding sources to implement proposed strategies.
As in the draft Phase I WIP, Delaware has shifted the entire urban stormwater load into the
WLA. This shift enhances reasonable assurance that nitrogen, phosphorus, and sediment
allocations from urban discharges will be achieved and maintained by signaling that many more
discharges could potentially be subject to NPDES permits as necessary to protect water quality.
HPA will maintain ongoing oversight of Delaware's urban stormwater sector. In particular, EPA
will monitor Delaware's progress in revising its urban stormwater regulations for new
development and redevelopment to be consistent with the final Phase I WIP commitments. EPA
also will monitor Delaware's efforts to develop a system for tracking inspections and compliance
information. Finally, EPA will review the timeline and content of proposed regulations to limit
turfgrass fertilizer use and the application of regulatory tools as a contingency should voluntary
programs not result in fertilizer reductions on 95 percent of available urban lands.
Delaware Wastewater
Delaware's final Phase 1 WIP showed key improvements in the wastewater sector. Most notably,
Delaware lowered effluent limits at 3 significant WWTPs to 4 mg/L TN at design flow to meet
the nitrogen allocations and committed to hire additional staff for the on-site treatment systems
and WWTP programs to manage permits consistent with the Chesapeake Bay TMDL. Delaware
also confirmed that all nonsignificant WWTPs are included within the WLA.
EPA will maintain ongoing oversight of Delaware's wastewater program to ensure that the
actions detailed in the final Phase I WIP occur and achieve the expected pollutant reductions.
EPA also will review NPDES permit conditions to ensure that they are consistent with the
assumptions and requirements of the Bay TMDL WLAs.
Delaware Conclusion
EPA applauds Delaware for its improvements in its Phase I WIP. The TMDL allocations in
Delaware are based solely on the final Phase I WIP because Delaware met its target allocations
and met EPA's expectations for providing reasonable assurance by identifying practices and
implementation strategies to attain applicable WQS. EPA will assess progress through ongoing
permit and program oversight and 2-year milestones, and believes that Delaware will succeed.
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Although KPA does not anticipate that additional federal actions will be necessary, F.PA is
prepared to object to permits, target enforcement, condition grants, or adopt other federal actions
as detailed in its December 29, 2010 letter, as necessary and appropriate, to support Delaware's
ambitious restoration commitment.
8.4.2 District of Columbia
The District of Columbia developed a final Phase 1 WIP that met the interim allocation target of
achieving a 60 percent reduction by 2017. and that met the nitrogen, phosphorus, and sediment
target allocations by 2025. The District's final Phase 1 WIP also met EPA's expectations for
providing reasonable assurance that those target allocations would be met, although it is
contingent in part upon the issuance of a final MS4 permit with performance standards for new
development, redevelopment, and retrofits that are similar to those included in the draft permit
issued earlier in 2010. As a result, EPA based the District's final allocations entirely on the
District's final Phase I WIP.
District of Columbia Allocations
The District of Columbia meets its nitrogen, phosphorus, and sediment allocations in the final
TMDL. based on FPA's quantitative and qualitative evaluation of the District's final Phase I
WIP. The District's input deck resulted in loads that are 0 percent over for nitrogen, phosphorus
and sediment allocations. The District of Columbia's Bay TMDL jurisdiction-wide allocations
are nitrogen 2.32 mpy; phosphorus 0.12 mpy; and sediment 11.16 mpy.
District of Columbia Urban Stormwater
The District of Columbia's final Phase I WIP showed significant improvements in urban
stormwater from its draft Phase I WIP. For example, the District's final WIP incorporates a new
urban stormwater volume standard (1.2-inch retention) that is consistent with the District's draft
MS4 permit. EPA anticipates that the final MS4 permit will include detailed information on
permit conditions, with timelines for implementation, tracking, inspections, and reporting. The
District's final Phase I WIP also includes a more detailed list of GSA properties and provides a
detailed discussion of the District's enforcement authority regarding federal properties. The WIP
also describes a plan for engaging federal facilities in the Phase II WIP, including tracking of
federal 2-year milestones.
EPA will maintain ongoing oversight of the District's urban stormwater sector and will continue
to work with DDOE to finalize the DC MS4 permit. EPA will assure specific permit conditions
and fact sheet language to reflect TMDL expectations (e.g., implementation action timelines,
inspection schedule, verification, and tracking). Once the DC MS4 permit is finalized, EPA will
continue to work with the District to implement the MS4 permit consistent with meeting 2-year
milestones and reporting for the TMDL.
District of Columbia Wastewater
The District of Columbia's final Phase I WIP also showed significant improvement in the
wastewater sector. Not only does the final Phase I WIP include a complete list of non-significant
facilities, but EPA and DC agreed upon the inclusion of a growth reserve in the final TMDL.
Although the final Phase I WIP and input deck do acknowledge the growth reserve, the final
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Chesapeake Bay TMDL
WLA for Blue Plains is separate and provides loading sufficient for and consistent with the
permit limits in the 2010 NPDES permit. If additional capacity is needed beyond the permitted
loads, the District has committed to work with other jurisdictions as necessary to adjust the Blue
Plains Inter-jurisdictional Municipal Agreement.
EPA will maintain ongoing oversight of the District's wastewater program and will implement
the TMDL WLAs through the permits that EPA issues, renews and modifies in the District of
Columbia. FPA also will continue to work closely with the District to assure that loads from both
significant and nonsignificant sources are consistent with the aggregate WLA. Specifically, the
final Phase I WIP proposes that the WLA for Blue Plains be developed based on the annual
average flows for outfall 001. However, WLAs for the combined sewer system (CSS) and its
associated WWTP in the District of Columbia are based on the limits in the NPDES permit
issued by EPA for Blue Plains and the Long Term Control Plan (LTCP) for the CSS system in
the District of Columbia. The WLAs assume full implementation of the Blue Plains LTCP.
District of Columbia Conclusion
EPA applauds the District of Columbia for its improvements in its Phase I WIP. EPA believes
that the District of Columbia will achieve and maintain its TMDL allocations based on its final
Phase I WIP. EPA commits to issue permits and target enforcement actions to implement TMDL
allocations. EPA also will encourage and work with its sister federal agencies to lead by example
in reducing nitrogen, phosphorus, and sediment loads into the Potomac and Anacostia rivers.
8.4.3 Maryland
Maryland developed a final Phase I WIP input deck with nitrogen, phosphorus, and sediment
controls that more than met the interim target allocations by achieving a 70 percent reduction by
2017, and met the nitrogen, phosphorus, and sediment target allocations by 2020. Maryland's
final Phase I WIP also met EPA's expectations for providing reasonable assurance that these
allocations will be met. As a result, EPA based Maryland's final allocations entirely on
Maryland's final Phase I WIP.
Maryland Allocations
Maryland meets its nitrogen, phosphorus, and sediment allocations for each basin in the final
TMDL, based on EPA's quantitative and qualitative evaluation of Maryland's final Phase I WIP.
Maryland submitted proposed modifications to its nitrogen, phosphorus, and sediment
allocations in each of its five basins. EPA used the Chesapeake Bay Water Quality Model to
confirm that these modifications would still attain applicable WQS. Maryland's final Phase I
WIP input deck resulted in jurisdiction-wide loads that are 0 percent over modified nitrogen,
phosphorus, and sediment allocations. Maryland's Bay TMDL jurisdiction-wide allocations are
nitrogen 39.09 mpy; phosphorus 2.72 mpy; and sediment 1218.10 mpy.
Maryland Agriculture
Maryland's final Phase I WIP showed significant improvements from its draft Phase I WIP in the
agriculture sector, including a strong contingency statement that significantly bolsters EPA's
reasonable assurance that Maryland will meet its agriculture targets by committing to explore
new policy measures and mandatory BMP compliance options. For example, these could include
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Chesapeake BayTMDL
a regulatory change that cover crops be planted on the highest risk acres. The Maryland final
Phase I W1P also provides more detail on phosphorus management, strengthens contingencies,
improves coordination with USDA, develops a plan for increasing staff levels, and selects a
subset of strategies to implement by 2017.
EPA will maintain ongoing oversight of Maryland's agriculture sector. EPA will use its national
review of CAFO State Technical Standards in 2011 as an opportunity to identify any deficiencies
in the State Technical Standards for protecting water quality. Through its review of State
Technical Standards. EPA also will evaluate whether Maryland's phosphorus management
program is sufficient to address phosphorous imbalances and water quality concerns. If
deficiencies are identified that are not addressed by Maryland or a CAFO permit does not
include other conditions to achieve nitrogen and phosphorus reductions identified in the final
Phase I WIP, EPA may object to permits if they are not protective of water quality.
Maryland Urban Stormwater
Maryland's final Phase I WIP also showed significant improvement in its commitment to urban
stormwater management. In the final Phase I WIP, Maryland committed to several actions to
ensure reductions, including limits on lawn fertilizer use, use of natural filters such as riparian
buffers and stream restoration, and an increase in watershed restoration requirements for MS4s
by requiring additional nitrogen, phosphorus, and sediment reductions. The WIP also included a
contingency plan whereby if local utilities or other systems of charges are not underway in 2012,
Maryland will seek legislation requiring development of local stormwater utilities via a statewide
system of fees. The final Phase I WIP also included descriptions of the policy, financing, and
tracking mechanisms for implementing urban stormwater retrofit programs.
Maryland also included in its final Phase I WIP specific activities and milestones for urban
stormwater program implementation, including the following:
• Renewal of Phase I MS4 permits to require nutrient and sediment reductions equivalent to
urban stormwater treatment on 30 percent of the impervious surface that does not have
adequate urban stormwater controls.
• Renewal of Phase II MS4 permits to require nutrient and sediment reductions equivalent to
urban stormwater treatment on 20 percent of the impervious surface that does not have
adequate urban stormwater controls.
• Renewal of State Highway Administration Phase 1 and Phase II MS4 permits to require
nutrient and sediment reductions equivalent to urban stormwater treatment on 30 percent of
the impervious surface that does not have adequate controls.
• Regulation of fertilizer applications on 220,000 acres of commercially managed lawns.
While EPA is satisfied overall with Maryland's demonstration of reasonable assurance, EPA will
closely track the nitrogen, phosphorus, and sediment reductions expected to result from these
urban stormwater retrofits. EPA will maintain ongoing oversight of Maryland's urban
stormwater sector and will assess how well Maryland is able to track and quantify outcomes
from the retrofits projected in its final Phase I WIP.
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Maryland Wastewater
Maryland's final Phase I WIP also showed significant improvement in the wastewater sector.
Maryland committed to identify options to structure the Bay Restoration Fund (BRF) fee in order
to fully fund Enhanced Nutrient Removal (ENR) upgrades at 67 public major wastewater
treatment plants. Options include fees based on consumption, income, or other criteria; and, in
2012, to propose an amendment to the BRF statute to change the BRF fee in order to provide
funding needed to complete the upgrades.. Maryland's final Phase I WIP also included a
contingency that if the BRF statute is not amended, "All funding for ENR projects will be
reduced from 100 percent grant to provide partial grant funds for each remaining project. Local
governments would be responsible for the balance of the necessary funding. State low interest
loan funds would be available to assist."
EPA will maintain ongoing oversight of Maryland's wastewater sector to ensure that the actions
detailed in the final Phase 1 WIP occur and achieve the expected pollutant reductions.
Maryland Conclusion
EPA applauds Maryland for following up a strong draft with an even stronger final Phase I WIP.
Maryland clarifies how its existing programs will implement nitrogen, phosphorus, and sediment
reductions ahead of schedule. Both Maryland and EPA are committed to carefully review
progress and adopt contingency actions as necessary to achieve and maintain the nitrogen.
phosphorus, and sediment reductions.
8.4.4 New York
New York developed a final Phase I WIP input deck with nitrogen, phosphorus, and sediment
controls that achieved additional reductions from the agricultural and wastewater sectors and
achieved jurisdiction-wide allocations for sediment, but did not meet allocations for nitrogen or
phosphorus. In response to New York's concerns regarding the fairness of how EPA distributed
the Bay wide allocations to jurisdictions, EPA increased New York's nitrogen and phosphorus
allocations by a total of 1,000,000 pounds and 100,000 pounds, respectively, and approved New
York's exchange of some phosphorus for nitrogen (see Section 6.4.5). New York still did not
meet its target allocations for nitrogen and phosphorus, however, despite these increased
allocations and nutrient exchanges. As described below, EPA closed the gap with an aggregate
WLA backstop allocation that further reduced New York's wastewater load.
New York Allocations
New York meets its modified nitrogen, phosphorus, and sediment allocations in the final TMDL,
based on a combination of EPA's quantitative and qualitative evaluation of New York's final
Phase I WIP, EPA's increase of New York's nitrogen and phosphorus allocations, EPA's
approval of New York's exchange of some phosphorus for nitrogen, and EPA's establishment of
a backstop allocation for wastewater as described in detail below. New York's final Phase I WIP
input deck resulted in loads that are 14 percent under its sediment allocation and 5 percent and 2
percent over its modified nitrogen and phosphorus allocations, respectively. EPA closed the gaps
between New York's WIP and its nitrogen and phosphorus allocations with an aggregate WLA
backstop allocation that further reduced New York's wastewater load. New York's jurisdiction-
wide allocations are nitrogen 8.77 mpy; phosphorus 0.57 mpy; and sediment 292.96 mpy.
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New York Agriculture
New York's final Phase 1 WIP showed significantly more details in the agriculture section to
demonstrate reasonable assurance that WIP commitments would be achieved than it did in its
draft. New York's final Phase I WIP is built on the strength of New York's Agricultural
Environmental Management (AEM) and CAFO programs. For example, AEM captures 95
percent of dairies in the watershed and farms must participate in AEM to get Farm Bill funding.
CAFO permits are required at dairies with as few as 200 animal units, and every field covered by
a nutrient management plan is tested for phosphorus. The WIP also includes a regulatory
requirement for pasture fencing as a contingency action, and outlines specific steps to implement
advanced technologies to process dairy manure. New York's final Phase I WIP also describes in-
depth strategies that support New York's BMP implementation rates. These strategies are based
on analyses of historic rates and cost of practices, realistic estimates of state and federal funding,
and the type of agriculture practiced in New York. These strategics met EPA's expectations for
reasonable assurance that New York will implement the commitments in its final Phase I WIP.
EPA will maintain ongoing oversight of New York's agriculture sector. EPA will use its
national review of CAFO State Technical Standards in 2011 and beyond as an opportunity to
identify any deficiencies in the State Technical Standards for protecting water quality. If
deficiencies are identified that are not addressed by the state or the permit does not include other
conditions to achieve nitrogen and phosphorus reductions identified in the final Phase I WIP,
EPA may object to permits if they are not protective of water quality.
New York Urban Stormwater
New York's final Phase I WIP showed improvement in the urban stormwater sector by better
documenting the strengths of its current program. New York volunteered to shift 50 percent of its
urban stormwater load from the LA to the WLA. This change enhances reasonable assurance that
nitrogen, phosphorus, and sediment allocations will be achieved and maintained by signaling that
substantially more urban stormwater could potentially be subject to NPDES permits issued by
New York as necessary to protect water quality. The final Phase I WIP also documented a
variety of funding sources to implement proposed strategies, and committed to BMPs that
address urban stormwater quality and quantity. In addition, the New York construction general
permit imposes volume-based post-construction controls on a significant portion of all
construction projects state-wide. New York also finalized legislation limiting the residential use
of fertilizer.
EPA will maintain ongoing oversight of New York's urban stormwater sector. EPA will monitor
New York's progress in implementing its urban stormwater program and issuing permits that
achieve the nitrogen, phosphorus, and sediment reductions that New York committed to in its
final Phase I WIP. EPA also will provide oversight of the urban stormwater permitting program.
New York Wastewater
In the wastewater sector, New York's final Phase I WIP included a commitment to improve
WWTP performance to BNR equivalent performance levels for nitrogen (8 mg/L) and to 0.5
mg/L for phosphorus at design flow. Despite increasing New York's nitrogen and phosphorus
allocations, however, New York's WIP did not reduce loads enough to meet the modified
8-23 December 29, 2010
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Chesapeake Bay TMDL
allocations. As a result, EPA applied backstop allocations and actions that further reduce New
York's WLA for wastewater to close the numeric gap.
EPA established an aggregate WLA for WWTPs that is calculated using the nitrogen and
phosphorus performance levels to which New York committed and that assumed that significant
WWTPs are at current flow rather than design flow. As discussed in Section 8.3, EPA allowed
for an aggregate WLA for WWTPs in New York to provide time for the New York State
Department of Environmental Conservation to review engineering reports from WWTPs and
determine the load reductions expected from each facility. New York has committed to provide
information to support individual WLAs for these WWTPs in its Phase II WIP. EPA understands
that New York plans to renew and/or modify WWTP permits after completing its Phase II WIP,
consistent with the applicable TMDL allocations at that time.
New York Conclusion
EPA values New York's continued commitment to protect its local waters and restore the
Chesapeake Bay through strong agricultural and urban stormwater programs as well as
commitments to reduce WWTP discharges. EPA has made adjustments to New York's
allocations based on concerns with equity (USEPA 201 Of)- EPA is confident that New York will
achieve its agricultural and urban stormwater allocations. EPA applied a backstop allocation to
further reduce wastewater loads to enable New York to meet its statewide nitrogen and
phosphorus allocations.
8.4.5 Pennsylvania
Pennsylvania developed a final Phase I WIP input deck with nitrogen, phosphorus, and sediment
controls that met its sediment allocations and came within two percent of jurisdiction-wide
nitrogen and phosphorus allocations after allowing for nitrogen to phosphorus exchanges.
Pennsylvania's final Phase I WIP resulted in loads below nitrogen, phosphorus, and sediment
allocations in the Potomac, Eastern, and Western Shore Basins. EPA will place the spare
allocation for these basins back into the agriculture nonpoint source sector. In contrast, after
allowing for nitrogen to phosphorus exchanges at EPA-approved ratios to modify the
Pennsylvania Susquehanna basin nitrogen and phosphorus allocations, the Commonwealth's
final Phase I WIP input deck remained 2 percent over its nitrogen allocation and 2 percent over
its phosphorus allocation. EPA and the Commonwealth have reached agreement on further
reductions from agricultural and urban stormwater nonpoint sources proportional to the amount
of load that they contribute to the Bay to achieve allocations in the Susquehanna in the final
TMDL. These further reductions are supported by contingencies included in the final Phase I
WIP and EPA's commitment to track progress and take any necessary federal actions to ensure
all pollutant reductions are achieved and maintained.
Pennsylvania's final Phase I WIP demonstrated substantially more reasonable assurance that it
could achieve and maintain agricultural allocations due to several key improvements. However,
as described below, Pennsylvania did not meet EPA's expectations for reasonable assurance that
urban stormwater allocations will be achieved and maintained. As described below, EPA closed
this reasonable assurance gap with a backstop adjustment for Pennsylvania's urban stormwater
load that transfers 50 percent of the urban stormwater load not currently subject to NPDES
permits from the LA to the WLA.
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Chesapeake BayTMDL
Pennsylvania Allocations
Pennsylvania met its nitrogen, phosphorus, and sediment allocations in each basin in the final
TMDL, based on a combination of EPA's quantitative and qualitative evaluation of
Pennsylvania's final Phase I WIP, EPA's commitment to enhanced oversight and actions for
Pennsylvania agriculture, EPA's approval of nitrogen and phosphorus exchanges, and EPA's
establishment of a backstop adjustment for urban stormwater as described in detail below. After
adjusting for EPA-approved nitrogen and phosphorus exchanges, Pennsylvania's WIP input deck
resulted in statewide loads that are 2 percent over for nitrogen and phosphorus, and 5 percent
under for sediment allocations. EPA and the Commonwealth have reached agreement on further
reductions from agriculture and urban stormwater nonpoint sources proportional to the amount of
load that they contribute to the Bay to achieve allocations in the Susquehanna and, therefore,
statewide. These further reductions are supported by the contingencies included in the WIP and
EPA's commitment to track progress and take any necessary federal actions to ensure these
reductions are achieved and maintained. Pennsylvania's final allocations are nitrogen 73.93 mpy;
phosphorus 2.93 mpy; and sediment 1983.78 mpy.
Pennsylvania Agriculture
Pennsylvania's final Phase I WIP showed significant improvement from the draft Phase I WIP in
the agriculture sector. The WIP included detailed strategies for increasing compliance with
agricultural regulations and for advancing manure technologies, and aligned Pennsylvania's
technical workforce to support WIP priorities. The Pennsylvania final Phase I WIP detailed a
specific approach for tracking agricultural conservation by working with EPA, the National
Association of Conservation Districts, and other Bay jurisdictions' agricultural agencies to
develop verification protocols for crediting non-cost-shared practices in the Chesapeake Bay
Watershed Model.
EPA wants Pennsylvania to succeed in achieving these reductions from the agriculture sector. To
support the Commonwealth's efforts, EPA will use its national review of CAFO State Technical
Standards in 2011 and beyond as an opportunity to identify any deficiencies in the State
Technical Standards for protecting water quality. EPA also will evaluate whether Pennsylvania's
approach to managing phosphorus is sufficient to address phosphorus imbalances and water
quality concerns. EPA will continue to engage Pennsylvania about the ways to phase out the
practice of winter spreading of manure, which continues to be allowed in Pennsylvania despite
being banned in other jurisdictions. If Pennsylvania does not adequately address these matters or
the permit does not include other conditions to achieve the nitrogen and phosphorus reductions
identified in its final Phase I WIP, EPA may object to permits if they are not protective of water
quality.
EPA also is committed to enhanced oversight and actions for Pennsylvania's agriculture sector.
Upon review of the Phase II WIP, EPA will revisit the WLAs for agriculture and WWTPs in the
event that Pennsylvania does not make significant progress in the following areas: receiving EPA
approval for its CAFO program, demonstrating enhanced compliance assurance with agricultural
state regulatory programs, developing more targeted contingency actions, and advancing manure
technologies. Specifically, EPA may consider
• More stringent phosphorus limits on WWTPs.
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Chesapeake Bay TMDL
• Shifting a greater portion of Pennsylvania's AFO load from the LA to the WLA. EPA
would assume full implementation of practices required under a CAFO permit for AFOs
included in the WLA. The shift to the WLA would signal that any of these AFOs could
potentially be subject to NPDES permits as necessary to protect water quality. AFOs would
only be subject to NPDES permit conditions issued by Pennsylvania upon designation.
EPA will consider this step if Pennsylvania does not achieve reductions in agricultural
loads as identified in the final Phase 1 WIP. EPA may also pursue designation activities
based upon considerations other than TMDL and WIP implementation.
Pennsylvania Urban Stormwater
Pennsylvania's final Phase 1 WIP also showed improvement in the urban stormwater sector. It
provided a strong description of Chapter 102 regulations and what Pennsylvania can enforce and
regulate to achieve no net change in urban stormwater runoff. The Commonwealth requires a no
net increase provision to maintain existing hydrology or demonstrate that at least 20 percent of a
previously disturbed site has the hydrologic conditions of meadow or better. The WIP also
included a commitment from PADEP to add a statewide program to reduce the application of
fertilizer on non-agricultural lands.
Despite these improvements, the WIP's urban stormwater discussion continues to have
weaknesses. Pennsylvania's final WIP lacked clear strategies to achieve the almost 40 percent
reduction in urban loads that the Commonwealth included in its WIP input deck. For example.
PADEP continues to assert that the scope of the MS4 program is limited to the conveyance
system only, and Pennsylvania's small MS4 permit program does not include construction and
post-construction requirements. Further, the requirement for an MS4 to have a TMDL
Implementation Plan does not include the Chesapeake Bay TMDL, and there is no supporting
documentation to quantify how local TMDL implementation plans will meet Bay targets. In
addition, Pennsylvania is assuming high compliance levels, but has not demonstrated a high level
of compliance assurance activities nor enhanced the field resources available to support an
enforcement presence. Recent EPA activities in this area have illustrated a high level of
noncompliance with existing permits.
As a result of the reasonable assurance weaknesses in the urban stormwater sector, EPA applied
backstop adjustments and actions to this sector. Specifically, EPA transferred 50 percent of the
urban stormwater load that is not currently subject to NPDES permits from the LA to the WLA.
This TMDL allocation adjustment increased reasonable assurance that nitrogen, phosphorus, and
sediment allocations from urban stormwater discharges will be achieved and maintained by
signaling that EPA is prepared to designate any of these discharges as requiring NPDES permits.
Urban areas would only be subject to NPDES permit conditions protective of water quality as
issued by the Commonwealth upon designation. EPA will consider this step if Pennsylvania does
not demonstrate progress toward reductions in urban loads identified in its final Phase I WIP.
EPA may also pursue designation activities based on considerations other than TMDL and WIP
implementation.
EPA will maintain close oversight of general permits for the Pennsylvania urban stormwater
sector (PAG-13, PAG-2) and may object as needed if permits are not protective of WQS and
regulations. Upon review of Pennsylvania's Phase II WIP, EPA will revisit the WLAs for
WWTPs, including more stringent phosphorus limits, in the event that Pennsylvania does not
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Chesapeake BayTMDL
reissue PA(i-l 3 and PAG-2 general permits for Phase II MS4s and construction activities that
are protective of water quality by achieving the load reductions called for in Pennsylvania's final
Phase I W1P.
Pennsylvania Wastewater
Pennsylvania's final Phase 1 WIP showed a number of key improvements in the wastewater
sector. For example, the WIP provided language on a process for granting 25 Ib/yr credit to
POTWs for each septic system retired and incorporated into a treatment facility and provided
additional language on implementation schedules for significant WWTP upgrades. In addition,
the final Phase I WIP and input decks included permit numbers for additional non-significant
facilities covered under the PAG-04 and PAG-05 general permits.
EPA committed to enhanced oversight and actions for the Pennsylvania wastewater sector, and
established individual WLAs for WWTPs in the TMDL to ensure that sufficient detail is
provided to inform individual permits for sources within the WLA. Provisions of this TMDL
allow (under certain circumstances, see Section 10) for modifications of allocations within a
basin to support offsets and trading opportunities. Further, as described above, EPA will assess
Pennsylvania's near-term urban stormwater and agricultural program progress and determine
whether t!PA should modify TMDL allocations to assume additional reductions from WWTPs.
Pennsylvania Conclusion
Pennsylvania's final Phase I WIP articulated a strategy to achieve its TMDL allocations.
Pennsylvania's final Phase I WIP contained significantly more detail than the draft Phase I WIP
and, with the incorporation of EPA's backstop adjustment and enhanced oversight, met EPA's
expectations for reasonable assurance that agricultural reductions can be achieved and
maintained. EPA is committed to enhanced oversight to ensure that necessary program
enhancements and load reductions are achieved in all sectors and that permits are consistent with
TMDL WLAs. Further, EPA applied a backstop adjustment for urban stormwater to signal that
substantially more urban stormwater discharges may need to be designated for coverage under
the NPDES program and receive NPDES permits from Pennsylvania that EPA deems are
protective of water quality.
8.4.6 Virginia
As described below, Virginia's final Phase I WIP showed significant improvements from its
draft Phase I WIP, including a commitment to implement aggressive, additional WWTP
upgrades, a more accountable urban stormwater program, and expanded mandatory agriculture
programs if voluntary programs are not successful. EPA is committing to ongoing oversight of
the agriculture and wastewater sectors and enhanced oversight of Virginia's urban stormwater
sector to ensure that WLAs and LAs are achieved and maintained.
Virginia Allocations
Virginia met its nitrogen, phosphorus, and sediment allocations for each basin in the final
TMDL, based on a combination of EPA's quantitative and qualitative evaluation of Virginia's
final Phase I WIP, EPA's approval of Virginia's exchange of some phosphorus for nitrogen, and
LPA's commitment to enhanced oversight and actions for Virginia urban stormwater. After
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Chesapeake Bay TMDL
adjusting for EPA-approved nitrogen and phosphorus exchanges, Virginia's WIP input deck
resulted in statewide loads that were 2 percent over for nitrogen and phosphorus, and 3 percent
under for sediment. Some individual basins, however, were as much as 5 percent over their
nitrogen and phosphorus target allocations, or 9 percent over their sediment target allocations.
EPA and the Commonwealth have reached agreement on further reductions from agricultural.
urban stormwater, and on-site septic system nonpoint sources proportional to the amount of load
that they contribute to the Bay to achieve allocations both jurisdiction-wide and in each basin in
the final TMDL. These further reductions are supported by the contingencies included in
Virginia's final Phase I WIP and EPA's commitment to track progress and take any necessary
federal actions to ensure these reductions are achieved and maintained. Virginia's jurisdiction-
allocations are nitrogen 53.42 mpy; phosphorus 5.36 mpy; and sediment 2578.90 mpy.
Virginia Agriculture
Virginia's final Phase I WIP showed a number of improvements in the agriculture sector. For
example, Virginia shifted the entire AFO load into the WLA and assumed full implementation of
barnyard runoff control, waste management, and mortality composting practices that would be
required under a CAFO permit. This change enhanced reasonable assurance that nitrogen,
phosphorus, and sediment allocations from animal operations will be achieved and maintained
by signaling that any of these facilities could potentially be subject to NPDES permits as
necessary to protect water quality. Virginia also committed to evaluating all small AFOs to
determine whether they discharge or propose to discharge and should be permitted. Virginia's
final Phase I WIP also provided more detail on the type of practices that are likely to be included
in Resource Management Plans and mechanisms for promoting these Plans to producers.
Virginia committed to pursue state legislation for mandatory actions or programs in the event
that the 2-year milestone agricultural reduction targets are not met, and provided assurance that
sufficient funding will be available through the 2013 milestone period.
EPA will maintain ongoing oversight of Virginia's agriculture program and will closely track
compliance with the agricultural milestone targets to ensure that appropriate contingency actions
are pursued as necessary. EPA will use its national review of CAFO State Technical Standards in
2011 and beyond to identify any deficiencies in the State Technical Standards for protecting
water quality. Through its review of CAFO State Technical Standards, EPA also will evaluate
whether Virginia's phosphorus management program is sufficient to address phosphorus. If
deficiencies are identified that are not addressed by the Commonwealth or the permit does not
include other conditions to achieve nutrient reductions identified in the WIP, EPA may object to
permits if they are not protective of water quality.
Virginia Urban Stormwater
Virginia's final Phase I WIP also showed improvement in the urban stormwater sector. Virginia
revised its WIP target loads to include much more achievable, yet still aggressive, load
reductions from the urban sector, committed to implement a Bay-wide and possibly statewide
regulatory program to limit fertilizer application on urban lands, and committed to finalize a
urban stormwater rule in 2011 that would improve new development and redevelopment
performance standards. Virginia also requested individual WLAs for Phase 1 MS4s to more
explicitly demonstrate the amount of urban runoff load that each permitted jurisdiction is
expected to achieve.
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Chesapeake BayTMDL
EPA committed to enhanced oversight and actions regarding Virginia's urban stormwater
program. Specifically, if the statewide rule and/or the Phase II WIP do not provide additional
assurance regarding how urban stormwater discharges outside of MS4 jurisdictions will achieve
nitrogen, phosphorus, and sediment reductions proposed in the final Phase I WIP and assumed
within the TMDL allocations, EPA may shift a greater portion of Virginia's urban stormwater
load from the LA to the WLA. This shift would signal that substantially more urban stormwater
could potentially be subject to NPDES permits issued by the Commonwealth as necessary to
protect water quality.
As in other Bay jurisdictions, EPA committed to ongoing oversight and actions. This includes
potentially objecting to proposed urban stormwater regulations, MS4 permits, construction
general permits, and industrial stormwater permits that are not consistent with the Bay TMDL
allocations and do not require conditions to reduce nitrogen, phosphorus, and sediment loads to
the degree identified in the final Phase I WIP.
Virginia Wastewater
Virginia's final Phase I WIP showed strong improvement in the wastewater sector. Virginia
committed to require WWTP upgrades in the James River Basin sufficient to achieve 100
percent of reductions needed to meet DO-based allocations and 60 percent of reductions needed
to meet chlorophyll-w based allocations by 2017. Virginia has committed to additional WWTP
upgrades to achieve 100 percent of the reductions needed to meet the chlorophyll-a based WLAs
for WWTPs by 2023, as outlined in the Staged Implementation Approach for Wastewater
Treatment Facilities in the Virginia James River Basin, which is found in Appendix X.
EPA will maintain ongoing oversight of Virginia's wastewater program. EPA will review
NPDES permit conditions to ensure that they are consistent with the assumptions and
requirements of the Bay TMDL WLA. If VADEQ and EPA cannot come to agreement on the
language of the Watershed General Permit related to combined sewer systems (CSS) by the time
that EPA reviews the Commonwealth's Phase II WIP, EPA may reopen WLAs to ensure that
they are reasonable and that compliance can be achieved.
Virginia Conclusion
Due to substantial improvements between the draft and final Phase I WIP, Virginia now
demonstrates that it can achieve and maintain nitrogen, phosphorus, and sediment allocations for
all source sectors. As a result, EPA has removed all backstop allocations for Virginia that it had
proposed in the draft TMDL. EPA commits to careful oversight to ensure that the valuable
commitments detailed in the final Phase I WIP are implemented on schedule, and that permits
and programs within the Commonwealth are consistent with assumptions and requirements of
the TMDL WLAs. EPA also will carefully assess the Phase II WIP to determine whether EPA
should establish a backstop adjustment for urban stormwater that shifts substantially more of the
unregulated load to the WLA.
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Chesapeake Bay TMDL
8.4.7 West Virginia
West Virginia developed a final Phase I WIP input deck with nitrogen, phosphorus, and sediment
controls that met its statewide target allocations when run through the Chesapeake Bay
Watershed Model after adjusting for EPA-approved nitrogen and phosphorus exchanges.
West Virginia's final Phase I WIP did not fully meet EPA's expectations for reasonable
assurance that agriculture allocations will be achieved, however. EPA closed the reasonable
assurance gap with a backstop adjustment for West Virginia's agriculture load that transferred 75
percent of West Virginia's AFO load into the WLA and assumed full implementation of
barnyard runoff control, waste management, and mortality composting practices. EPA also
committed to enhanced oversight of Virginia's urban stormwater and wastewater sectors to
ensure that they achieve and maintain their allocations.
EPA based West Virginia's final allocations on a combination of West Virginia's final Phase I
WIP with the above backstop adjustment for animal agriculture and enhanced oversight actions
for urban stormwater and wastewater as described below.
West Virginia Allocations
West Virginia met its nitrogen, phosphorus, and sediment allocations for each basin in the final
TMDL, based on a combination of EPA's quantitative and qualitative evaluation of West
Virginia's final Phase I WIP, EPA's commitment to enhanced oversight and actions for West
Virginia urban stormwater and wastewater, and EPA's establishment of a backstop adjustment
for West Virginia agriculture as described in detail below. After adjusting for EPA-approved
nitrogen and phosphorus exchanges, West Virginia's input deck resulted in statewide loads that
are 0 percent under nitrogen, 1 percent under phosphorus and 11 percent under sediment
allocations.
West Virginia agreed that any spare allocations in the Potomac River Basin would go to a LA
reserve. Results from the final Phase I WIP input deck exceed nitrogen, phosphorus, and
sediment allocations by 51 percent, 18 percent and 76 percent in the West Virginia portion of the
James River basin, however. These exceedances are in large part due to an increasing portion of
loads in West Virginia reaching the tidal portions of the James River as downstream loads
decrease. EPA and West Virginia have reached agreement to fill these gaps by assuming
additional reductions from all nonpoint sources proportional to the amount of loads they
discharge to the Bay. West Virginia has committed to explore additional opportunities for
reducing loads in this basin. EPA will track progress and consider whether to adopt additional
federal actions to ensure that reductions are achieved and maintained. Furthermore, EPA will
consider the effect of delivery factors when evaluating options for allocating basinwide loads to
the major basins and jurisdictions in 2011. West Virginia's jurisdiction-wide allocations are
nitrogen 5.45 mpy; phosphorus 0.59 mpy; and sediment 310.88 mpy.
West Virginia Agriculture
West Virginia's final Phase I WIP included some improvements. For example, it focused on
effective nutrient-reducing practices such as poultry litter transport, targeted Nutrient
Management Plans in high nitrogen-loading counties, and stream fencing. West Virginia also has
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Chesapeake Bay TMDL
increased coordination efforts with USDA to support proposed agriculture strategies and
implementation.
West Virginia's final Phase I WIP contained a number of weaknesses in the agriculture sector,
however. The WIP lacked detailed strategies for how West Virginia will implement nitrogen,
phosphorus, and sediment controls on agricultural lands at levels necessary to meet TMDL
allocations. The WIP also lacked strong contingencies such as new policies, programs, or
mandates in the event that voluntary approaches are not sufficient to meet reduction goals. West
Virginia's recently approved CAFO program has not yet had an opportunity to demonstrate a
successful track record for AFO outreach and permitting.
To address these reasonable assurance weaknesses, EPA applied backstop adjustments and
actions to this sector. Specifically, EPA shifted 75 percent of West Virginia's AFO load into the
Wl.A and assumed full implementation of barnyard runoff control, waste management, and
mortality composting practices required under a CAFO permit on these AFOs. This adjustment
increased reasonable assurance that nitrogen, phosphorus, and sediment allocations for the
agriculture sector will be achieved and maintained by signaling that EPA is prepared to designate
any of these AFOs as requiring NPDES permits. The shift signaled that any of these operations
could potentially be subject to NPDES permits as necessary to protect water quality. AFOs
would only be subject to NPDES permit conditions as issued by West Virginia upon designation.
EPA will consider this step if West Virginia does not achieve reductions in agricultural loads as
identified in the WIP. EPA also may pursue designation activities based upon considerations
other than TMDL and WIP implementation. Based upon EPA's review of the state technical
standards, the number of permit applications and permits issued under the new CAFO program.
and progress towards developing programs to reduce agricultural loads, EPA will assess in the
Phase II WIP whether more stringent WLAs for WWTPs are necessary to ensure that TMDL
allocations are achieved.
In addition, EPA committed to ongoing oversight and actions consistent with other Bay
jurisdictions. EPA will use its national review of CAFO State Technical Standards in 2011 and
beyond as an opportunity to identify any deficiencies in the State Technical Standards for
protecting water quality. Through its review of CAFO State Technical Standards. EPA also will
evaluate whether West Virginia's phosphorus management program is sufficient to address
phosphorus imbalances and water quality concerns. If deficiencies are identified that are not
addressed by the state or a permit does not include other conditions to achieve nutrient
reductions identified in the WIP, EPA may object to permits if they are not protective of water
quality.
West Virginia Urban Stormwater
West Virginia's final Phase I WIP showed some improvement in the urban stormwater sector.
For example. West Virginia clarified contingencies in its final Phase I WIP, including
mechanisms to regulate urban stormwater discharges from new development and redevelopment
outside of regulated MS4 areas and implementation of retrofits to reduce pollutant loads from
existing discharges.
The WIP still has weaknesses in its demonstration of reasonable assurance that urban stormwater
allocations will be achieved and maintained, however. As a result. EPA committed to enhanced
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Chesapeake Bay TMDL
oversight and actions of West Virginia's urban stormwater program to ensure implementation. If
urban stormwater rules and/or the Phase II WIP do not provide additional assurance regarding
how urban stormwater discharges outside of MS4 jurisdictions will achieve nitrogen,
phosphorus, and sediment reductions proposed in the final WIP and assumed within the TMDL
LAs, EPA may shift a greater portion of West Virginia's urban stormwater load from the LA to
the WLA. The shift would signal that substantially more urban stormwater could potentially be
subject to NPDES permits issued by West Virginia as necessary to protect water quality. EPA
will also monitor any increased discharges above the current baseline, as no reductions from
permitted urban stormwater are expected. Finally, as in other Bay jurisdictions, EPA commits to
ongoing oversight to ensure that programs and permits are consistent with WIP commitments. If
they are not. EPA is prepared to take other federal actions as identified in its December 29, 2009
letter to ensure that TMDL allocations are achieved and maintained.
West Virginia Wastewater
West Virginia's final Phase I WIP showed improvement in the wastewater sector. For example,
it included a commitment for the West Virginia legislature in 2011 to consider mechanisms to
enhance financial assistance for POTWs to facilitate prompt compliance with NPDES permit
requirements resulting from the Chesapeake Bay TMDL. West Virginia also provided additional
information on compliance schedules and limits in the Permit Compliance System, and
committed to reevaluate certain wastewater dischargers in its Phase II WIP to determine whether
it will be necessary to reallocate loads.
Despite these improvements, however, the WIP does not fully meet EPA's expectations for
reasonable assurance. As a result, EPA committed to enhanced oversight and actions for the
West Virginia wastewater sector and, consistent with West Virginia's input deck, established
individual WLAs for significant WWTPs in the TMDL to ensure that sufficient detail is provided
to inform individual permits for sources within the wastewater WLA. Provisions of this TMDL
allow (under certain circumstances, see Section 10) for modifications of allocations within a
basin to support offsets and trading opportunities. Further, as described above, EPA will assess
West Virginia's near-term agriculture program progress and determine whether additional
federal actions consistent with EPA's December 29, 2009 letter, such as modifying TMDL
allocations to assume additional reductions from WWTPs, are necessary to ensure that TMDL
allocations are achieved.
West Virginia Conclusion
In summary, West Virginia's final Phase I WIP did not meet EPA's expectations for reasonable
assurance for the agriculture sector. However, it did include an input deck with nitrogen,
phosphorus, and sediment controls that, if implemented, would achieve statewide allocations.
EPA wants West Virginia to successfully implement its final Phase I WIP. To fill the remaining
reasonable assurance gap, EPA applied a backstop adjustment that shifted a portion of
unregulated AFO production area loads into the WLA as a signal that substantially more
operations may be subject to NPDES permits to protect water quality. Consistent with its
December 29, 2009 letter, EPA is also prepared to take other federal actions as detailed in its
December 29, 2010 letter as necessary to ensure that West Virginia succeeds in achieving the
load reductions identified in its final Phase I WIP.
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Chesapeake Bay TMDL
8.5 ALLOCATION SUMMARY CHART
The final allocations for nitrogen, phosphorus, and sediment listed above also are presented in
Table 8-5 at both the jurisdiction and major river basin scales for each of the jurisdictions. These
allocations are further sub-allocated to the 92 Bay segment watersheds by individual and
aggregate WLAs and LAs in Section 9.
Table 8-5. Chesapeake Bay watershed nitrogen, phosphorus, and sediment allocations
by jurisdiction and by major river basin, in millions of pounds per year
Jurisdiction
Pennsylvania
Maryland
Virginia
District of Columbia
New York
Delaware
West Virginia
Major river
basin
Susquehanna
Potomac
Eastern Shore
Western Shore
PA Total
Susquehanna
Eastern Shore
Western Shore
Patuxent
Potomac
MD Total
Eastern Shore
Potomac
Rappahannock
York
James
VA Total
Potomac
DC Total
Susquehanna
NY Total
Eastern Shore
DE Total
Potomac
James
WV Total
Preliminary Baywide Allocation
Atmospheric Deposition Allocation*
Total Baywide Allocation
Nitrogen
allocations
(million Ibs/year)
68.90
4.72
0.28
0.02
73.93
1.09
9.71
9.04
2.86
16.38
39.09
1.31
17.77
5.84
5.41
23.09
53.42
2.32
2.32
8.77
8.77
295
2.95
5.43
002
5.45
185.93
15.7
201.63
Phosphorus
allocations
(million Ibs/year)
2.49
0.42
0.01
0.00
2.93
0.05
1.02
0.51
0.24
0.90
2.72
0.14
1.41
0.90
0.54
2.37
5.36
0.12
0.12
0.57
0.57
026
0.26
0.58
0.01
0.59
12.54
N/A
12.54
Sediment
allocations
(million Ibs/year)
1,741 17
221.11
21.14
0.37
1,983.78
62.84
168.85
199.82
106.30
680.29
1,218.10
11.31
829.53
700.04
117.80
920.23
2,578.90
11.16
11.16
292.96
292.96
57.82
57.82
294.24
16.65
310.88
6,453.61
N/A
6,453.61
3 Cap on atmospheric deposition loads direct to Chesapeake Bay and tidal tributary surface waters to be achieved by
federal air regulations through 2020.
Note: These basin-jurisdiction allocations have been modified from the original allocations established by EPA earlier
this summer for the following reasons
1 New York's allocations for nitrogen and phosphorus have been adjusted;
2 West Virginia's allocation for sediment has been corrected;
3. Maryland's allocations have been adjusted for some jurisdiction-requested basin exchanges;
4 Sever al other jurisdictions requested nutrient exchanges in their final Phase I WIPs
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SECTION 9. CHESAPEAKE BAY TMDLS
This section presents the segment-specific and sector-specific Chesapeake Bay TMDL
allocations for nitrogen, phosphorus, and sediment that resulted from EPA's evaluation of the
jurisdictions' final Phase I WIPs as described in Section 8.
The MO$ is implicit for the nitrogen and phosphorus allocations, having been built into the suite
of decision-making tools, procedures and assumptions described in the previous sections (see
Section 6.2.4). In the case of the sediment allocations, the explicit MOS is built directly into the
allocations themselves (see Section 6.5.4). Natural background loads are included in the LAs
presented in this section and the referenced appendices.
9.1 BAY SEGMENT ANNUAL AND DAILY ALLOCATIONS TO MEET
WQS
Tables 9-1, 9-2, and 9-3 provide the annual total nitrogen, total phosphorus, and total suspended
solids (sediment) allocations, respectively, for the watershed areas draining to each of the 92
Chesapeake Bay segments necessary to meet their applicable WQS. Those allocations are
calculated as delivered loads (the loading that actually reaches tidal waters) and as annual loads.
These tables are structured by major basin from north to south with western shore first and
eastern shore second. The Bay and tidal tributary segments themselves are listed in geographic
order from the head of tide down river from north to south. Each of the 92 segments is displayed
as white rows while contributing portions of some of the 92 segments are displayed as gray rows.
Table 9-4 provides the individual WLAs (annual) for total nitrogen, total phosphorus, and total
suspended solids (sediment) for each of the 478 significant permitted dischargers. All WLAs
listed in Table 9-4 are calculated as edge-of-stream loads (the loading that reaches a simulated
stream segment from a point in that stream's watershed). More detailed LAs and WLAs are
provided in Appendix Q for annual TMDLs and in Appendix R for daily TMDLs.
9-1 December 29, 2010
-------
Table 9-1. Chesapeake Bay TMDL total nitrogen (TN) annual allocations' (pounds per year) by Chesapeake Bay segment" to attain
Chesapeake Bay WQS
Segment ID
CB1TF
CB1TF
CB1TF
CB1TF
BSHOH
GUNOH
GUNOH
GUNOH
MIDOH
BACOH
PATMH
MAGMH
SEVMH
SOUMH
RHDMH
WSTMH
WBRTF
PAXTF
PAXOH
PAXMH
ANATF MD
ANATF MD
ANATF MD
ANATF DC
ANATF DC
ANATF DC
POTTF MD
POTTF MD
POTTF MD
POTTF MD
Jurisdiction
NY
PA
MD
MD
PA
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
DC
MD
DC
PA
MD
DC
VA
CB 303(d) Segment
Northern Chesapeake Bay
Northern Chesapeake Bay
Northern Chesapeake Bay
Northern Chesapeake Bay
Bush River
Gunpowder River
Gunpowder River
Gunpowder River
Middle River
Back River
Patapsco River
Magothy River
Severn River
South River
Rhode River
West River
Western Branch Patuxent River
Upper Patuxent River
Middle Patuxent River
Lower Patuxent River
Anacostia River, MD
Anacostia River. MD
Anacostia River. MD
Anacostia River. DC
Anacostia River. DC
Anacostia River, DC
Upper Potomac River. MD
Upper Potomac River. MD
Upper Potomac River, MD
Upper Potomac River. MD
TNWLA
(Ibs/yr)
1.305,533
13,938,796
292,953
15,537,282
445.589
90
255,714
255,804
31,639
1,700,239
3,475,456
48,270
244,630
49,303
14,888
5,292
97,386
1,110,871
11,563
27,816
294.029
11.055
305.084
39,160
41,153
80.313
342,541
2,634,386
15,397
2.189,118
TN Land
Based LA
(Ibs/yr)
7,466.415
54,965.400
1,173.509
63,605,325
282.015
19.866
792,403
812.269
26,896
23,108
606,149
91,496
114,992
98,704
20.632
22,517
116,500
685,570
267,180
456,617
149.357
970
150.327
6,780
17,652
24.432
4,378,072
9,009.270
3.038
9,815,634
TN AtDepc
LA (Ibs/yr)
337,488
68,092
73,337
32,551
25,010
213,246
45,831
64,618
37,585
13,683
18,626
360
12,074
28,352
148,769
1.124
7.248
TNTMDL
(Ibs/yr)
8,771.948
68,904,197
1,466.462
79,480,095
795,696
19.957
1,048,117
1,141,411
91.085
1,748.357
4,294,851
185,597
424,239
185,591
49,203
46.435
214,246
1,808,516
307,095
633.203
443.386
12.026
456.535
45.940
58.805
111.993
4,720,613
11,643.656
18.435
12,004.752
TN 2009
Existing
(Ibs/yr)
10,947,653
101.652.996
1,943,851
114.544,499
930,895
30,135
1,305,958
1,336,092
147,687
2,233,080
7,602,511
236,865
445,316
219,201
53,329
39,366
239,170
1,768,198
359,289
627,161
507,448
13,640
521.088
54,823
131,992
186.815
6,228,235
13.520,999
202,365
13,761,560
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Table 9-1. Chesapeake Bay TMDL total nitrogen (TN) annual allocations' (pounds per year) by Chesapeake Bay segment" to attain
Chesapeake Bay WQS
Segment ID
POTTF MD
POTTF MD
POTTF DC
POTTF DC
POTTF DC
POTTF DC
POTTF VA
PISTF
MATTF
POTOH1 MD
POTOH1 MD
POTOH1 MD
POTOH2 MD
POTOH3 MD
POTOH VA
POTMH MD
POTMH MD
POTMH MD
POTMH VA
RPPTF
RPPOH
RPPMH
CRRMH
MPNTF
MPNOH
PMKTF
PMKOH
PIAMH
Jurisdiction
WV
MD
DC
VA
VA
MD
MD
MD
VA
MD
MD
VA
MD
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
CB 303(d) Segment
Upper Potomac River. MD
Upper Potomac River. MD
Upper Potomac River. DC
Upper Potomac River. DC
Upper Potomac River, DC
Upper Potomac River, DC
Upper Potomac River, VA
Piscataway Creek
Mattawoman Creek
Middle Potomac River. MD Mainstem
Middle Potomac River, MD Mainstem
Middle Potomac River. MD Mainstem
Middle Potomac River, MD Nangemoy
Creek
Middle Potomac River, MD Port Tobacco
River
Middle Potomac River, VA
Lower Potomac River, MD
Lower Potomac River. MD
Lower Potomac River. MD
Lower Potomac River, VA
Upper Rappahannock River
Middle Rappahannock River
Lower Rappahannock River
Corrotoman River
Upper Mattaponi River
Lower Mattaponi River
Upper Pamunkey River
Lower Pamunkey River
Piankatank River
TNWLA
(Ibs/yr)
472,895
5.654,338
2.102,951
2.205,248
692,389
5,000,589
2,912,791
426,385
44.833
2,259
5,603
7,862
41.351
6,165
144,881
200.139
168
200,307
127,796
713.032
438
56.873
21.563
55,429
11,425
313,111
301,581
32,045
TN Land
Based LA
(Ibs/yr)
4,961.651
28,167,664
48.466
23.829
12.535
84,831
487,502
88,969
124.244
46,281
24.015
70,296
81,080
102,258
366,024
933.683
57,574
991,257
877,532
3,427,258
203.619
961,971
135,107
971,640
125,500
1,602,061
64,773
313,841
TN AtDepc
LA (Ibs/yr)
164,918
34,413
74,213
6,263
8,762
309,297
13,562
19,613
36.719
1,047,100
81,362
52,969
28,473
522,040
37,232
19,845
15,545
22,674
16,059
72,763
TN TMDL
(Ibs/yr)
5,434.546
33,986.920
2,151,417
2,229,078
704,924
5,119,832
3,474,506
521,617
177,840
48,540
29,617
387,455
135,993
128,036
547,624
1.133.822
57,742
2,238,664
1,086,690
4,193,259
232,530
1,540,883
193,902
1,046,913
152,470
1,937,846
382,413
418.650
TN 2009
Existing
(Ibs/yr)
5,909,347
39,622.506
2,340,588
2.507,384
880,860
5,728,832
3.634,235
463,644
198,150
55,152
33,122
88,274
136.802
121,907
569,992
1,370.808
78,506
1.449,314
1,280,940
4,724,938
273,194
1,353,400
177,281
1,268.961
172,806
2,137,617
311,629
394,383
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Table 9-1. Chesapeake Bay TMDL total nitrogen (TN) annual allocations' (pounds per year) by Chesapeake Bay segment" to attain
Chesapeake Bay WQS
Segment ID
YRKMH
YRKPH
MOBPH
JMSTF2
JMSTF2
JMSTF2
JMSTF1
APPTF
CHKOH
JMSOH
JMSMH
JMSPH
ELIPH
WBEMH
SBEMH
EBEMH
LAFMH
LYNPH
NORTF
NORTF
NORTF
ELKOH
ELKOH
ELKOH
ELKOH
C&DOH DE
C&DOH DE
C&DOH DE
C&DOH MD
C&DOH MD
Jurisdiction
VA
VA
VA
wv
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
PA
MD
PA
DE
MD
DE
MD
DE
MD
CB 303(d) Segment
Middle York River
Lower York River
Mobjack Bay
Upper James River Upper
Upper James River Upper
Upper James River Upper
Upper James River Lower
Appomattox River
Chickahominy River
Middle James River
Lower James River
Mouth of James River
Mouth to mid Elizabeth River
Western Branch Elizabeth River
Southern Branch Elizabeth River
Eastern Branch Elizabeth River
Lafayette River
Lynnhaven River
Northeast River
Northeast River
Northeast River
Elk River
Elk River
Elk River
Elk River
C&D Canal, DE
C&D Canal. DE
C&D Canal. DE
C&D Canal. MD
C&D Canal, MD
TNWLA
(Ibs/yr)
15,026
61,648
712,032
376
5,013,858
5.014,234
2.551,063
421,341
46,371
278,731
480,063
1,022.650
418,811
119,709
246,851
162,243
70,367
409.349
1,324
55,341
56.665
39,372
2.193
92,717
134,283
5,787
1
5,788
15,427
10,954
TN Land
Based LA
(Ibs/yr)
333,648
107,505
351.903
17.325
8.298,038
8,315,363
531,401
1,392,078
300,704
275.044
733,761
7,286
10,120
29,560
76,507
9,662
1,941
25,873
33.132
177.361
210.493
210.104
8.312
277.145
495.562
14.830
105
14.935
38.028
37.855
TN AtDepc
LA (Ibs/yr)
164,516
119,007
366,485
178,108
30,245
26,741
37,675
207.608
590,001
116,792
52,778
14,005
18,868
14,810
7,274
5,728
31.564
83.506
18.818
TN TMDL
(Ibs/yr)
513,189
288,160
1,430,420
17,701
13,311.896
13,507,705
3,112,709
1,840,160
384,750
761.382
1,803.824
1,146,728
481.709
163,274
342,226
186,716
79,582
440.951
34.456
232.702
298.723
249.476
10.506
369.863
713.351
20.617
106
39.540
53,455
48.808
TN 2009
Existing
(Ibs/yr)
428,617
165,661
1,518,048
23,854
15,313,468
15,337,322
3,440,277
2,169,402
407,317
730,672
1,960,753
3,346,988
1.233,036
161,521
416,080
263,580
71,296
1,850.029
55,984
253.404
309,388
385,703
12,615
470.335
868.653
29,732
193
29.925
72,814
59,686
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Table 9-1. Chesapeake Bay TMDL total nitrogen (TN) annual allocations' (pounds per year) by Chesapeake Bay segment" to attain
Chesapeake Bay WQS
Segment ID
C&DOH MD
BOHOH
BOHOH
BOHOH
SASOH
SASOH
SASOH
CHSTF
CHSTF
CHSTF
CHSOH
CHSMH
EASMH
CHOTF
CHOTF
CHOTF
CHOOH
CHOMH2
CHOMH1
LCHMH
HNGMH
FSBMH
NANTF DE
NANTF DE
NANTF DE
NANTF MD
NANTF MD
NANTF MD
NANOH
NANOH
Jurisdiction
DE
MD
DE
MD
DE
MD
MD
MD
MD
DE
MD
MD
MD
MD
MD
MD
MD
DE
MD
DE
MD
DE
MD
CB 303(d) Segment
C&D Canal. MD
Bohemia River
Bohemia River
Bohemia River
Sassafras River
Sassafras River
Sassafras River
Upper Chester River
Upper Chester River
Upper Chester River
Middle Chester River
Lower Chester River
Eastern Bay
Upper Choptank River
Upper Choptank River
Upper Choptank River
Middle Choptank River
Mouth of Choptank River
Lower Choptank River
Little Choptank River
Honga River
Fishing Bay
Upper Nanticoke, DE
Upper Nanticoke, DE
Upper Nanticoke, DE
Upper Nanticoke, MD
Upper Nanticoke, MD
Upper Nanticoke, MD
Middle Nanticoke River
Middle Nanticoke River
TNWLA
(Ibs/yr)
26.381
5,059
4,676
9.735
266
6,320
6,585
1,973
8.590
10.563
24.337
48.244
33,621
5,477
38,113
43.590
56,463
112,961
8.904
1,454
494
12,125
320,160
210
320.371
0
6.883
6.883
6.253
56.861
TN Land
Based LA
(Ibs/yr)
75.882
31.069
127,984
159.053
25.867
253,244
279.111
108.560
419,379
527.939
491.394
426,553
553.829
247.037
1,117,792
1,364.829
475,043
239,223
282,914
179,887
46,750
617.858
1,689.986
16,295
1,706,282
231
50.104
50,335
322,431
605,179
TN AtDepc
LA (Ibs/yr)
10.602
34.514
65.635
13.240
39.045
214.655
309,901
33.376
59,131
130.585
257,748
102.495
96.162
81,039
33.839
39,790
TN TMDL
(Ibs/yr)
112,865
36.128
132.660
203.302
26.133
259.563
351.331
110.534
427,969
551.742
554.776
689,453
897.352
252.514
1,155.905
1,441.796
590,637
482.769
549,565
283,836
143,406
711.023
2,010.146
16.506
2,060.492
231
56,986
97,007
328.684
662.040
TN 2009
Existing
(Ibs/yr)
132.501
56,121
182,321
238,442
42,936
398,175
441,111
162,575
576,551
739,126
802,555
633,424
795,200
376,251
1.479,532
1.855,784
653,485
385,997
380,753
225,829
59,280
792,951
2.773.808
25,772
2,799,580
355
67,870
68,226
475,395
838,869
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Table 9-1. Chesapeake Bay TMDL total nitrogen (TN) annual allocations' (pounds per year) by Chesapeake Bay segment" to attain
Chesapeake Bay WQS
Segment ID
NANOH
NANMH
WICMH
WICMH
WICMH
MANMH
BIGMH
POCTF
POCTF
POCTF
POCOH_MD
POCOH VA
POCOH VA
POCOH VA
POCMH MD
POCMH VA
TANMH MD
TANMH VA
CB2OH
CB3MH
CB4MH
CB5MH MD
CB5MH VA
CB6PH
CB7PH
CB8PH
All
Jurisdiction
MD
DE
MD
MD
MD
DE
MD
MD
MD
VA
MD
VA
MD
VA
MD
MD
MD
MD
VA
VA
VA
VA
All
CB 303(d) Segment
Middle Nanticoke River
Lower Nanticoke River
Wicomico River
Wicomico River
Wicomico River
Manokin River
Big Annemessex River
Upper Pocomoke River
Upper Pocomoke River
Upper Pocomoke River
Middle Pocomoke River. MD
Middle Pocomoke River. VA
Middle Pocomoke River, VA
Middle Pocomoke River, VA
Lower Pocomoke River, MD
Lower Pocomoke River, VA
Tangier Sound, MD
Tangier Sound. VA
Upper Chesapeake Bay
Upper Central Chesapeake Bay
Middle Central Chesapeake Bay
Lower Central Chesapeake Bay, MD
Lower Central Chesapeake Bay, VA
Western Lower Chesapeake Bay
Eastern Lower Chesapeake Bay
Mouth of Chesapeake Bay
All
TNWLA
(Ibs/yr)
63,114
2.120
1,926
147,286
149,212
42,169
2,677
1,603
39,327
40,931
2,353
770
3,176
3,946
1,317
36,905
14,635
0
22,867
113,726
69,854
74,462
65.831
80
52,274
135,685
53,358,309
TN Land
Based LA
(Ibs/yr)
927,610
111,021
6.610
500,869
507,479
211,375
71,365
91,833
767,616
859,449
61,218
58,791
131,816
190,607
92,217
203,748
86,546
5,583
252,884
72,325
232,568
86,384
312.716
26,860
874,208
24,511
132.563,059
TN AtDepc
LA (Ibs/yr)
39,025
66,561
81,392
88,913
71,912
20,328
44,935
7,659
124,041
157,367
612,332
307,485
434,345
529,188
1,188,056
957,593
594.229
707,095
1,739,897
609,543
15,700,000
TNTMDL
(Ibs/yr)
1,029,748
179,702
8,536
648,154
738.082
342.457
145,954
93.436
806.943
920,708
108.506
59,560
134,992
202,212
217,575
398,020
713,512
313,068
710,096
715,239
1,490,477
1,118,439
972.776
734,034
2,666,379
769.739
201,621,368
TN 2009
Existing
(Ibs/yr)
1,314,264
127,980
12,256
902,542
914,798
249,077
80,947
132,227
887,951
1,020,178
72,356
69,459
185,664
255,123
99,014
510,169
120,118
5,823
404,690
193,692
393,898
208,367
483,600
32,282
1,301,326
162,895
249,262,775
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a. MOS is implicit for nitrogen (see Section 6.2.4)
b. Each of the 92 segments is displayed as white rows while contributing portions of some of the 92 segments are displayed as gray rows.
c. AtDep means atmospheric deposition only for direct deposition to tidal waters.
Note: Any differences between this table and Table 8-5 are due to rounding.
-------
Table 9-2. Chesapeake Bay TMDL total phosphorus (TP) annual allocations' (pounds per year) by Chesapeake Bay segment to attain
Chesapeake Bay WQS
O
ro
n
ID
3
a-
o
»-»
o
Segment ID
CB1TF
CB1TF
CB1TF
CB1TF
BSHOH
GUNOH
GUNOH
GUNOH
MIDOH
BACOH
PATMH
MAGMH
SEVMH
SOUMH
RHDMH
WSTMH
WBRTF
PAXTF
PAXOH
PAXMH
ANATF MD
ANATF MD
ANATF MD
ANATF DC
ANATF DC
ANATF DC
POTTF MD
POTTF MD
POTTF MD
Jurisdiction
NY
PA
MD
MD
PA
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
DC
MD
DC
PA
MD
DC
CB 303(d) Segment
Northern Chesapeake Bay
Northern Chesapeake Bay
Northern Chesapeake Bay
Northern Chesapeake Bay
Bush River
Gunpowder River
Gunpowder River
Gunpowder River
Middle River
Back River
Patapsco River
Magothy River
Severn River
South River
Rhode River
West River
Western Branch Patuxent River
Upper Patuxent River
Middle Patuxent River
Lower Patuxent River
Anacostia River. MD
Anacostia River. MD
Anacostia River. MD
Anacostia River, DC
Anacostia River. DC
Anacostia River. DC
Upper Potomac River, MD
Upper Potomac River, MD
Upper Potomac River. MD
TPWLA
(Ibs/yr)
101.576
1.207.756
23.108
1.332.440
33.173
18
17,669
17.686
3,392
95,781
212,595
5,910
23,149
6,620
1,339
960
15,001
98,055
3,081
16.584
33,237
1,433
34,669
6.384
6.845
13,229
59,991
194.657
619
TP Land
Based LA
(Ibs/yr)
464,126
1.287.074
47,626
1,798,827
9,155
983
20.713
21,697
440
788
14,772
1,772
3,499
5,232
1,962
2,123
6,353
41,553
20,573
30.632
7,208
95
7.303
357
2.283
2,641
361,850
379,011
65
TP TMDL
(Ibs/yr)
565,702
2.494.830
70.734
3,131.267
42.328
1.001
38,382
39,383
3.832
96.569
227.366
7.682
26,647
11.852
3,301
3.083
21,354
139,607
23,654
47.216
40.445
1,528
41,973
6,741
9.129
15.870
421,841
573.668
685
TP 2009
Existing
(Ibs/yr)
801,589
3.409.157
82.274
4,293.020
63.813
1.062
58.656
59,719
11,819
75.530
397.260
20.754
50,568
19.690
4,354
4,227
26,163
150.585
31,358
63.861
61,485
2,705
64.190
10.799
27.387
38,186
537,617
696.408
21,433
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Table 9-2. Chesapeake Bay TMDL total phosphorus (TP) annual allocations* (pounds per year) by Chesapeake Bay segment" to attain
Chesapeake Bay WQS
Segment ID
POTTF MD
POTTF MD
POTTF MD
POTTF DC
POTTF DC
POTTF DC
POTTF DC
POTTF VA
PISTF
MATTF
POTOH1 MD
POTOH1 MD
POTOH1 MD
POTOH2 MD
POTOH3 MD
POTOH VA
POTMH MD
POTMH MD
POTMH MD
POTMH VA
RPPTF
RPPOH
RPPMH
CRRMH
MPNTF
MPNOH
PMKTF
PMKOH
PIAMH
YRKMH
Jurisdiction
VA
WV
MD
DC
VA
VA
MD
MD
MD
VA
MD
MD
VA
MD
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
CB 303(d) Segment
Upper Potomac River, MD
Upper Potomac River, MD
Upper Potomac River, MD
Upper Potomac River, DC
Upper Potomac River, DC
Upper Potomac River, DC
Upper Potomac River, DC
Upper Potomac River, VA
Piscataway Creek
Mattawoman Creek
Middle Potomac River, MD Mainstem
Middle Potomac River, MD Mainstem
Middle Potomac River, MD Mainstem
Middle Potomac River, MD Nangemoy Creek
Middle Potomac River. MD Port Tobacco River
Middle Potomac River, VA
Lower Potomac River. MD
Lower Potomac River, MD
Lower Potomac River, MD
Lower Potomac River, VA
Upper Rappahannock River
Middle Rappahannock River
Lower Rappahannock River
Corrotoman River
Upper Mattaponi River
Lower Mattaponi River
Upper Pamunkey River
Lower Pamunkey River
Piankatank River
Middle York River
TPWLA
(Ibs/yr)
208,723
63,734
527,724
99,835
107,806
36,476
244,117
201,920
26,339
8.741
592
1.033
1.624
4,809
1,116
14,012
22,450
29
22,479
14.146
99,695
51
7,522
2.406
12,270
787
35,785
59,373
5.207
2,736
TP Land
Based LA
(Ibs/yr)
780,655
519,726
2,041,307
1,511
1.801
397
3,710
32,105
5,481
6,889
3,603
1,722
5,325
5,234
8,243
23.931
88.603
5,270
93.873
84,514
630,035
19.923
94.953
11,569
72.110
11,291
133,955
5,525
38,034
28,149
TP TMDL
(Ibs/yr)
989,378
583,459
2.569.031
101,347
109.607
36,873
247,827
234,026
31.820
15.630
4,195
2,755
6,950
10,043
9,358
37,943
111,053
5,300
116.352
98,660
729,730
19,974
102,475
13,975
84,380
12.078
169,740
64.898
43.241
30,885
TP 2009
Existing
(Ibs/yr)
1,591,680
819,300
3.666.438
46,383
34,853
30.368
111,604
193,977
25,394
20.655
4.415
3.077
7,492
11,413
9,972
38.482
125,786
7.079
132.864
135.581
875.321
23.141
130,960
16.049
102,834
15.988
201,331
61.342
49,451
39,514
n
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-------
Table 9-2. Chesapeake Bay TMDL total phosphorus (TP) annual allocations' (pounds per year) by Chesapeake Bay segment" to attain
Chesapeake Bay WQS
o
o>
o
(D
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ro
O
Segment ID
YRKPH
MOBPH
JMSTF2
JMSTF2
JMSTF2
JMSTF1
APPTF
CHKOH
JMSOH
JMSMH
JMSPH
ELIPH
WBEMH
SBEMH
EBEMH
LAFMH
LYNPH
NORTF
NORTF
NORTF
ELKOH
ELKOH
ELKOH
ELKOH
C&DOH DE
C&DOH DE
C&DOH DE
C&DOH MD
C&DOH MD
C&DOH MD
Jurisdiction
VA
VA
WV
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
PA
MD
PA
DE
MD
DE
MD
DE
MD
CB 303(d) Segment
Lower York River
Mobjack Bay
Upper James River Upper
Upper James River Upper
Upper James River Upper
Upper James River Lower
Appomattox River
Chickahominy River
Middle James River
Lower James River
Mouth of James River
Mouth to mid Elizabeth River
Western Branch Elizabeth River
Southern Branch Elizabeth River
Eastern Branch Elizabeth River
Lafayette River
Lynnhaven River
Northeast River
Northeast River
Northeast River
Elk River
Elk River
Elk River
Elk River
C&D Canal, DE
C&D Canal, DE
C&D Canal. DE
C&D Canal, MD
C&D Canal. MD
C&D Canal, MD
TPWLA
(Ibs/yr)
7,994
85,291
107
496,605
496,712
103,556
46,961
19,822
19,360
70,805
82,383
23.109
20,931
44.856
32,418
11,703
43,629
141
5,334
5.475
4,606
317
9,506
14,428
897
0
897
2.323
1.742
4,065
TP Land
Based LA
(Ibs/yr)
7,734
27,892
9,645
999,919
1,009.564
46,904
130,326
47.781
19,766
70,647
330
579
2,153
5,994
637
128
1,816
1.439
6.600
8.039
7,752
441
15,600
23,793
1,855
13
1,867
3,601
3,413
7,013
TP TMDL
(Ibs/yr)
15,727
113.183
9,752
1,496,524
1.506,276
150,460
177,287
67.603
39,125
141,451
82,712
23,689
23,083
50,850
33,055
11,831
45.445
1,580
11,934
13.515
12,357
758
25,106
38.221
2,752
13
2.765
5.924
5,155
11,079
TP 2009
Existing
(Ibs/yr)
16,751
127.487
13..917
1.973,287
1.987.204
131.562
241.572
79.799
74,626
187,692
194,769
63.685
25,012
68,406
45,115
13,403
123,014
2.214
13,211
15.425
17,281
911
30,123
48,315
3,379
37
3,415
7,212
6.496
13.708
n
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-------
Table 9-2. Chesapeake Bay TMDL total phosphorus (TP) annual allocations' (pounds per year) by Chesapeake Bay segment to attain
Chesapeake Bay WQS
Segment ID
BOHOH
BOHOH
BOHOH
SASOH
SASOH
SASOH
CHSTF
CHSTF
CHSTF
CHSOH
CHSMH
EASMH
CHOTF
CHOTF
CHOTF
CHOOH
CHOMH2
CHOMH1
LCHMH
HNGMH
FSBMH
NANTF_DE
NANTF DE
NANTF_DE
NANTF MD
NANTF MD
NANTF MD
NANOH
NANOH
NANOH
Jurisdiction
DE
MD
DE
MD
DE
MD
MD
MD
MD
DE
MD
MD
MD
MD
MD
MD
MD
DE
MD
DE
MD
DE
MD
CB 303(d) Segment
Bohemia River
Bohemia River
Bohemia River
Sassafras River
Sassafras River
Sassafras River
Upper Chester River
Upper Chester River
Upper Chester River
Middle Chester River
Lower Chester River
Eastern Bay
Upper Choptank River
Upper Choptank River
Upper Choptank River
Middle Choptank River
Mouth of Choptank River
Lower Choptank River
Little Choptank River
Honga River
Fishing Bay
Upper Nanticoke. DE
Upper Nanticoke. DE
Upper Nanticoke. DE
Upper Nanticoke. MD
Upper Nanticoke. MD
Upper Nanticoke. MD
Middle Nanticoke River
Middle Nanticoke River
Middle Nanticoke River
TPWLA
(Ibs/yr)
807
735
1.543
42
1.675
1.716
304
1,467
1,771
4,798
5,961
2,630
1,101
5,779
6.880
5,145
9.873
1.683
229
75
1.440
25.589
48
25.637
0
1,147
1.147
983
7,398
8,381
TP Land
Based LA
(Ibs/yr)
4,134
13,191
17,326
3.629
28.505
32.134
12,791
45,823
58.614
54,074
44,742
61,927
31,531
116.838
148,368
55,704
28.001
33.233
19,780
4,314
67,261
128.715
1,752
130.467
18
6.057
6.076
33.399
67,078
100,477
TP TMDL
(Ibs/yr)
4.941
13.927
18.868
3,671
30,180
33.851
13.095
47,290
60.385
58,872
50,703
64.557
32,631
122,617
155,248
60,850
37,874
34,915
20.008
4.389
68.701
154,304
1,800
156.104
18
7.204
7.223
34.382
74,475
108.858
TP 2009
Existing
(Ibs/yr)
6,017
20,230
26.246
4,469
36.981
41.450
16,298
52,108
68,407
67.837
52,278
71,988
41,664
147,321
188.985
63,666
41.658
40.931
22.960
6.603
78.173
181.200
2,901
184.100
22
7.011
7.033
42.964
84,307
127,271
01
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Table 9-2. Chesapeake Bay TMDL total phosphorus (TP) annual allocations' (pounds per year) by Chesapeake Bay segment" to attain
Chesapeake Bay WQS
3
o-
n
N>
to
Segment ID
NANMH
WICMH
WICMH
WICMH
MANMH
BIGMH
POCTF
POCTF
POCTF
POCOH MD
POCOH VA
POCOH VA
POCOH_VA
POCMH MD
POCMH VA
TANMH MD
TANMH VA
CB20H
CB3MH
CB4MH
CB5MH MD
CB5MH VA
CB6PH
CB7PH
CB8PH
All
Jurisdiction
MD
DE
MD
MD
MD
DE
MD
MD
MD
VA
MD
VA
MD
VA
MD
MD
MD
MD
VA
VA
VA
VA
All
CB 303(d) Segment
Lower Nanticoke River
Wicomico River
Wicomico River
Wicomico River
Manokin River
Big Annemessex River
Upper Pocomoke River
Upper Pocomoke River
Upper Pocomoke River
Middle Pocomoke River, MD
Middle Pocomoke River, VA
Middle Pocomoke River, VA
Middle Pocomoke River, VA
Lower Pocomoke River, MD
Lower Pocomoke River, VA
Tangier Sound. MD
Tangier Sound, VA
Upper Chesapeake Bay
Upper Central Chesapeake Bay
Middle Central Chesapeake Bay
Lower Central Chesapeake Bay. MD
Lower Central Chesapeake Bay. VA
Western Lower Chesapeake Bay
Eastern Lower Chesapeake Bay
Mouth of Chesapeake Bay
All
TPWLA
(Ibs/yr)
238
295
13.499
13.794
6,225
405
326
4.437
4.763
991
234
547
782
194
2.587
1,353
0
3.063
9.263
7.487
5,766
6,100
7
5.565
23,848
4,512.260
TP Land
Based LA
(Ibs/yr)
9,550
496
45.386
45.882
22.502
7.462
8,212
84.571
92.783
6.981
7,255
14,959
22.214
10,453
21,905
6,051
492
25,092
6,948
14,191
6.977
29,609
2,277
96.646
1,161
8,030,114
TP TMDL
(Ibs/yr)
9,788
792
58.884
59,676
28,727
7.867
8.538
89.007
97,546
7,972
7.490
15,506
22,996
10.646
24,493
7,405
492
28,155
16.211
21.678
12,744
35.710
2,284
102,211
25,009
12,542,374
TP 2009
Existing
(Ibs/yr)
11,165
969
85,428
86.397
25.686
8.318
10,255
95,447
105,702
8.174
7.781
20,922
28,703
11.173
31,873
8,275
527
34,772
23,949
35.651
28.818
45,025
2,773
140,064
30,461
16,462,955
a. MOS is implicit for phosphorus (see Section 6.2.4)
t>. Each of the 92 segments is displayed as white rows while contnbuting portions of some of the 92 segments are displayed as gray rows.
Note: Any differences between this table and Table 8-5 are due to rounding.
n
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rt>
01
7T
n
CD
Ol
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5
-------
Table 9-3. Chesapeake Bay TMDL sediment (TSS)" annual allocations" (pounds per year) by Chesapeake Bay segment0 to attain
Chesapeake Bay WQS
Segment ID
CB1TF
CB1TF
CB1TF
CB1TF
BSHOH
GUNOH
GUNOH
GUNOH
MIDOH
BACOH
PATMH
MAGMH
SEVMH
SOUMH
RHDMH
WSTMH
WBRTF
PAXTF
PAXOH
PAXMH
ANATF MD
ANATF MD
ANATF MD
ANATF DC
ANATF DC
ANATF DC
POTTF MD
POTTF MD
POTTF MD
POTTF MD
Jurisdiction
NY
PA
MD
MD
PA
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
DC
MD
DC
PA
MD
DC
VA
CB 303(d) Segment
Northern Chesapeake Bay
Northern Chesapeake Bay
Northern Chesapeake Bay
Northern Chesapeake Bay
Bush River
Gunpowder River
Gunpowder River
Gunpowder River
Middle River
Back River
Patapsco River
Magothy River
Severn River
South River
Rhode River
West River
Western Branch Patuxent River
Upper Patuxent River
Middle Patuxent River
Lower Patuxent River
Anacostia River. MD
Anacostia River. MD
Anacostia River. MD
Anacostia River, DC
Anacostia River, DC
Anacostia River, DC
Upper Potomac River, MD
Upper Potomac River. MD
Upper Potomac River. MD
Upper Potomac River MD
TSSWLA
(Ibs/yr)
42,014,121
152.686,225
5.949,689
200,650,035
13,196,649
3,892
9,239,345
9,243,237
509,743
15,955,266
56,849,993
901,450
2,991,739
1,090,181
172,442
118,448
9,492,711
27,928,151
501,122
853.761
47.005.706
317,718
47.323,423
790.954
1,616,149
2,407.104
7,119,122
65.621.675
446,556
52.111,881
TSSLA
(Ibs/yr)
250.946.605
1.588.480.781
64,361,278
1.903,788,665
15,973,700
368,273
38,001,024
38.369,297
236,484
410,195
31,375,105
535,226
935,655
1,071,766
474,811
634,597
10,104,173
40,733,517
7,721.654
8.070.930
22.921,343
21,960
22.943.303
90.167
511,485
601.651
213.989,662
430.700.804
47.439
645,079,928
TSS TMDL
(Ibs/yr)
292.960,727
1,741.167.006
70,310,967
2.104,438,699
29,170,349
372,165
47.240,369
47,612,534
746,227
16,365,461
88.225,098
1,436,676
3,927,394
2,161,947
647,253
753,044
19,596,885
68,661,668
8,222,777
8.924.690
69,927,049
339,678
70.266.727
881,121
2.127,634
3.008,755
221.108,783
496.322.479
493,995
697,191,809
TSS 2009
Existing
(Ibs/yr)
337,266,496
2,286.387,566
81.125,570
2,704,779,632
35,527,626
765,816
58,189,414
58.955.230
1,576,785
9,421,900
113.667,512
2,101,536
3,716,445
3,022.869
739,818
998.390
23.382.999
67.673,319
10.784,126
12.133.210
111.245,825
609,892
111.855.717
1,620,633
4,743.620
6.364,253
309.605.976
549,338,715
18.182.239
955.858,637
o
n>
tu
cu
rt>
03
o
O
n
o
n>
I
N>
NJ
o
-------
Table 9-3. Chesapeake Bay TMDL sediment (TSS)' annual allocations" (pounds per year) by Chesapeake Bay segment0 to attain
Chesapeake Bay WQS
Segment ID
POTTF MD
POTTF_MD
POTTF DC
POTTF DC
POTTF DC
POTTF DC
POTTF VA
PISTF
MATTF
POTOH1_MD
POTOH1 MD
POTOH1 MD
POTOH2 MD
POTOH3 MD
POTOH VA
POTMH MD
POTMH MD
POTMH MD
POTMH VA
RPPTF
RPPOH
RPPMH
CRRMH
MPNTF
MPNOH
PMKTF
PMKOH
PIAMH
YRKMH
YRKPH
Jurisdiction
WV
MD
DC
VA
VA
MD
MD
MD
VA
MD
MD
VA
MD
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
CB 303(d) Segment
Upper Potomac River. MD
Upper Potomac River. MD
Upper Potomac River. DC
Upper Potomac River. DC
Upper Potomac River. DC
Upper Potomac River, DC
Upper Potomac River. VA
Piscataway Creek
Mattawoman Creek
Middle Potomac River. MD Mainstem
Middle Potomac River. MD Mainstem
Middle Potomac River. MD Mainstem
Middle Potomac River. MD Nangemoy Creek
Middle Potomac River. MD Port Tobacco River
Middle Potomac River. VA
Lower Potomac River. MD
Lower Potomac River. MD
Lower Potomac River. MD
Lower Potomac River. VA
Upper Rappahannock River
Middle Rappahannock River
Lower Rappahannock River
Corrotoman River
Upper Mattaponi River
Lower Mattaponi River
Upper Pamunkey River
Lower Pamunkey River
Piankatank River
Middle York River
Lower York River
TSS WLA
(Ibs/yr)
4.251,816
129,551.049
26.116,504
6.290,046
7.990.096
40,396,647
73,817.620
4,420.894
2,164.085
141.182
126.225
267,408
517.854
173.198
6,193,677
7.436,553
9.492
7,446,045
604,405
21.344,146
7,877
904,914
32,486
1,092,098
59.447
6,026,107
13,086,736
803,391
290,754
514,729
TSS LA
(Ibs/yr)
289.983.789
1.579.801,621
6,077,446
1.906,768
348.443
8,332,657
23,707,878
3.164,315
3.781,157
1,503,199
192,470
1,695,669
1,777,500
2.851,267
7,882,449
53.034,527
490.435
53.524,962
6.899,027
624,671,576
9,936,097
37,705,787
1,064,500
13,603.734
1,105,563
47,032,619
674,771
9,372,914
10,716,330
968,271
TSS TMDL
(Ibs/yr)
294.235,605
1.709.352,671
32,193,949
8,196,814
8.338,540
48.729,304
97.525,497
7,585,209
5.945,242
1.644,382
318,695
1,963,077
2,295,354
3.024,465
14,076,126
60,471.080
499.928
60,971,007
7,503,432
646,015,721
9.943,973
38,610,700
1,096,986
14,695,833
1,165,010
53,058,726
13.761,507
10.176,305
11,007,084
1.483.000
TSS 2009
Existing
(Ibs/yr)
349.862,416
2,182.847.983
25,474,106
8,467.385
6,385,015
40,326,507
101,055,750
6,198.882
6.897.769
1.928,927
374.540
2,303,467
2,662.195
3,509.912
17,280.595
72.595.650
682,793
73,278.444
10,266,702
709,235,879
1,225,958
38,050,038
1,275,873
22,576,525
1,604,598
84,819,341
1.518,896
13.746.640
4.087.532
2.101,402
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T3
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00
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o
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ro
o
-------
Table 9-3. Chesapeake Bay TMDL sediment (TSS)1 annual allocations" (pounds per year) by Chesapeake Bay segment" to attain
Chesapeake Bay WQS
Segment ID
MOBPH
JMSTF2
JMSTF2
JMSTF2
JMSTF1
APPTF
CHKOH
JMSOH
JMSMH
JMSPH
ELIPH
WBEMH
SBEMH
EBEMH
LAFMH
LYNPH
NORTF
NORTF
NORTF
ELKOH
ELKOH
ELKOH
ELKOH
C&DOH DE
C&DOH DE
C&DOH DE
C&DOH MD
C&DOH MD
C&DOH MD
BOHOH
Jurisdiction
VA
WV
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
PA
MD
PA
DE
MD
DE
MD
DE
MD
DE
CB 303(d) Segment
Mobjack Bay
Upper James River Upper
Upper James River Upper
Upper James River Upper
Upper James River Lower
Appomattox River
Chickahominy River
Middle James River
Lower James River
Mouth of James River
Mouth to mid Elizabeth River
Western Branch Elizabeth River
Southern Branch Elizabeth River
Eastern Branch Elizabeth River
Lafayette River
Lynnhaven River
Northeast River
Northeast River
Northeast River
Elk River
Elk River
Elk River
Elk River
C&D Canal, DE
C&D Canal, DE
C&D Canal, DE
C&D Canal. MD
C&D Canal, MD
C&D Canal. MD
Bohemia River
TSSWLA
(Ibs/yr)
8,727,001
35,199
67,286,234
67,321,434
15,607,897
26,032,004
939,747
2,999,553
7,332,882
11,502,783
4,694,148
2,006,272
3,556,563
3,356,476
1,977,709
7,233,702
52,337
3,822,591
3,874,928
950,124
31.854
. 1,639,790
2.621.768
140,066
14
140.079
336,975
107,601
444.576
65,521
TSS LA
(Ibs/yr)
3,433,596
16.609,948
612,850,612
629,460,560
24,690,254
62,293,157
18,584,599
20,449,110
27,529,658
34,350
52,510
147,738
375,463
24,188
12,922
174,719
2.078,118
10,695,417
12.773.535
18,055,981
64,385
7,052,756
25,173.121
414.748
4,012
418,760
825,087
969,513
1.794,600
514,661
TSS TMDL
(Ibs/yr)
12.160,596
16.645.148
680,136,846
696,781,994
40,298,151
88,325,161
19,524,346
23,448,664
34,862.540
11,537,133
4,746,658
2.154,010
3.932.026
3,380,664
1,990,631
7.408,420
2,130.456
14,518.008
16.648,463
19.006,105
96,239
8,692,546
27.794,890
554,814
4,026
558.840
1,162,062
1.077.114
2.239.176
580,182
TSS 2009
Existing
(Ibs/yr)
14.112,361
28,519,899
1,059,920.428
1,088,440,327
9,015,473
106,140,533
4,841,974
6,690,974
25,514,847
6,505,447
3.056,281
2,636,798
4,741,119
4.406,458
2,336,093
7.882,520
3,258,381
16.472.012
19.730,393
28.398,346
106,497
9,998,038
38.502.881
626,615
4,677
631.292
1.291,350
1.258,787
2.550.137
624,140
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Table 9-3. Chesapeake Bay TMDL sediment (TSS)" annual allocations" (pounds per year) by Chesapeake Bay segment0 to attain
Chesapeake Bay WQS
Segment ID
BOHOH
BOHOH
SASOH
SASOH
SASOH
CHSTF
CHSTF
CHSTF
CHSOH
CHSMH
EASMH
CHOTF
CHOTF
CHOTF
CHOOH
CHOMH2
CHOMH1
LCHMH
HNGMH
FSBMH
NANTF DE
NANTF DE
NANTF DE
NANTF MD
NANTF MD
NANTF MD
NANOH
NANOH
NANOH
NANMH
Jurisdiction
MD
DE
MD
DE
MD
MD
MD
MD
DE
MD
MD
MD
MD
MD
MD
MD
DE
MD
DE
MD
DE
MD
MD
CB 303(d) Segment
Bohemia River
Bohemia River
Sassafras River
Sassafras River
Sassafras River
Upper Chester River
Upper Chester River
Upper Chester River
Middle Chester River
Lower Chester River
Eastern Bay
Upper Choptank River
Upper Choptank River
Upper Choptank River
Middle Choptank River
Mouth of Choptank River
Lower Choptank River
Little Choptank River
Honga River
Fishing Bay
Upper Nanticoke. DE
Upper Nanticoke, DE
Upper Nanticoke. DE
Upper Nanticoke. MD
Upper Nanticoke. MD
Upper Nanticoke. MD
Middle Nanticoke River
Middle Nanticoke River
Middle Nanticoke River
Lower Nanticoke River
TSS WLA
(Ibs/yr)
64,402
129.923
5,525
286,930
292.455
93.984
137,542
231.526
298,598
528,519
576,343
361,498
1.261,836
1.623,334
558,079
966.759
386.256
98.483
10,644
81,663
10.827,397
5.894
10,833,291
0
28,289
28.289
361,062
817.307
1,178,369
40,737
TSS LA
(Ibs/yr)
3.167,619
3.682,279
642,671
8,289.784
8,932.455
2.860.897
12.094,797
14.955,694
9.332,711
12.292,064
9,815.207
6.182.065
17.937,463
24.119,528
4.015,407
2.978,930
4,567,610
3,097,933
531,405
4,576,273
27.256,751
104,157
27,360,908
680
495.823
496.502
6.223,525
6.910,025
13,133,549
743,265
TSS TMDL
(Ibs/yr)
3.232,020
3.812.203
648,196
8.576.714
9.224,910
2,954.881
12.232,339
15.187,220
9,631,310
12.820,583
10,391,551
6.543,563
19,199,299
25,742,862
4,573,486
3.945,688
4,953,867
3,196,416
542,049
4.657,936
38.084,149
110,051
38,194.199
680
524,111
524.791
6.584,587
7.727,332
14,311,918
784,002
TSS 2009
Existing
(Ibs/yr)
3.777,673
4.401,813
684,780
10.011,983
10.696.763
3,357,254
13.409,995
16.767,249
10.775,054
14.312,931
11,324,723
7.462,694
20,356,821
27.819,515
4.510,268
3,789.712
5,815.588
3,487,049
646,232
5.111.822
42,177,643
128,452
42.306.095
721
557,353
558,073
7.739,104
8.184,073
15.923,178
827,854
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Table 9-3. Chesapeake Bay TMOL sediment (TSS)' annual allocations" (pounds per year) by Chesapeake Bay segment' to attain
Chesapeake Bay WQS
Segment ID
WICMH
WICMH
WICMH
MANMH
BIGMH
POCTF
POCTF
POCTF
POCOH MD
POCOH VA
POCOH VA
POCOH VA
POCMH MD
POCMH VA
TANMH MD
TANMH VA
CB20H
CB3MH
CB4MH
CB5MH MD
CB5MH VA
CB6PH
CB7PH
CB8PH
All
Jurisdiction
DE
MD
MD
MD
DE
MD
MD
MD
VA
MD
VA
MD
VA
MD
MD
MD
MD
VA
VA
VA
VA
All
CB 303(d) Segment
Wicomico River
Wicomico River
Wicomico River
Manokin River
Big Annemessex River
Upper Pocomoke River
Upper Pocomoke River
Upper Pocomoke River
Middle Pocomoke River MD
Middle Pocomoke River. VA
Middle Pocomoke River, VA
Middle Pocomoke River. VA
Lower Pocomoke River. MD
Lower Pocomoke River, VA
Tangier Sound. MD
Tangier Sound. VA
Upper Chesapeake Bay
Upper Central Chesapeake Bay
Middle Central Chesapeake Bay
Lower Central Chesapeake Bay, MD
Lower Central Chesapeake Bay, VA
Western Lower Chesapeake Bay
Eastern Lower Chesapeake Bay
Mouth of Chesapeake Bay
All
TSSWLA
(Ibs/yr)
104.196
1.664.605
1 768.802
333.932
28.574
62,520
481.873
544 393
196,894
46.287
12,493
58,780
55,660
65.386
189,923
18
383.801
1,022,587
1,058,853
631,522
446,801
453
518.824
2,787,517
898,226,531
TSS LA
(Ibs/yr)
39.998
4.687.746
4727744
1.216,362
602,203
406.956
10.323.430
10730.387
588 961
636,117
653,177
1,289,295
1.264.202
1,102,827
415.636
416,465
7,474,139
1.957,395
3,258,291
1,513,513
3,626,293
294,130
8.538.667
64,200
5,555.386.665
TSS TMDL
(Ibs/yr)
144,195
6.352.351
6496.545
1.550,294
630 777
469,476
10.805.303
11 274,779
785,855
682,405
665.670
1 348.075
1,319.862
1.168,213
605.560
416,483
7,857,940
2,979.982
4.317,144
2,145,035
4,073,093
294.582
9,057,491
2,851,717
6,453,613,196
TSS 2009
Existing
(Ibs/yr)
174.874
7,198,430
7 373,305
1.492,064
666,385
532,895
11,359.483
11.892 378
797,483
718,647
977.918
1 696,564
1.370,010
1,610.806
679,354
19,960
9.344,169
2.646,201
5,413,881
2.042,464
5.353.666
387,639
13,772.993
3,580,118
8,090,521.521
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a. Upon review and after consideration of public comments, EPA has determined that Total Suspended Solids (TSS) is a more appropriate expression of the
sediment load than Total Sediment (TSED), which was used in the draft TMDL. As a result the allocation tables in the draft TMDL that were expressed as TSED
have been changed such that they now are expressed as TSS.
b. MOS is implicit and explicit for TSS (see Section 6 5.4)
c. Each of the 92 segments is displayed as white rows while contributing portions of some of the 92 segments are displayed as gray rows.
Note: Any differences between this table and Table 8-5 are due to rounding.
-------
Table 9-4. Edge of Stream (EOS) WLAs (Annual) for the 478 significant permitted dischargers to meet TMDLs to attain the Chesapeake
Bay WQS
lp
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Permit Name
BLUE PLAINS
INVISTA (DUPONT-SEAFORD)
LAUREL
BRIDGEVILLE
SEAFORD
COX CREEK
HART MILLER
MASONVILLE DMCF
W R GRACE
MD & VA MILK PRODUCERS
ISG SPARROWS POINT (BETHLEHEM
STEEL CORP)
CONGOLEUM
NEWPAGE
ERACHEM
NSWC-INDIAN HEAD
WINEBRENNER WWTP
CRISFIELD
CHESTERTOWN
INDIAN HEAD
BOONSBORO
FEDERALSBURG
EMMITSBURG
EASTON
CHESAPEAKE BEACH
DENTON
LA PLATA
DELMAR
PERRYVILLE
PRINCESS ANNE
NPDES ID
DC0021199
DE0000035
DE0020125
DE0020249
DE0020265
MD COXCRK
MDJHARTMI
MD MASNV
MD0000311
MD0000469
MD0001201
MD0001384
MD0001422
MD0001775
MD0003158
MD0003221
MD0020001
MD0020010
MD0020052
MD0020231
MD0020249
MD0020257
MD0020273
MD0020281
MD0020494
MD0020524
MD0020532
MD0020613
MD0020656
Jurisdiction
DC"
DE
DE
DE
DE
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
Segment ID
POTTF DC
NANTF DE
NANTF DE
NANTF DE
NANTF DE
PATMH
MIDOH
PATMH
PATMH
PAXTF
PATMH
PATMH
POTTF MD
PATMH
MATTF
POTTF MD
TANMH MD
CHSMH
MATTF
POTTF MD
NANOH
POTTF_MD
CHOOH
CB4MH
CHOTF
POTOH2 MD
WICMH
CB1TF
MANMH
TNEOS
WLA
(Ibs/yr)
4,689,000
171,818
8,528
9,746
24,364
231,101
0
231,101
310,721
5,431
131,420
4,005
12,733
13,809
1,777
12,182
12,182
18,273
6,091
6,100
9,137
9,137
48,729
18,273
9,746
18,273
10,355
20,101
11,512
TPEOS
WLA
(Ibs/yr)
203,854
0
2,132
2.436
6,091
3,614
0
3,614
1,782
543
25,400
160
597
58
727
914
914
1,371
457
484
685
685
3,655
1,371
731
1,371
777
1.508
1.151
TSS EOS
WLA (Ibs/yr)
8,198,328
749,208
31,978
36,547
48,729
193,606
0
193,606
334,037
42,150
85,863
19,324
124,473
8,352
41,937
91,367
91,367
137,050
45,683
48,424
68,525
68,525
365,467
137,050
73,093
137,050
77,662
150,755
115,122
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Table 9-4. Edge of Stream (EOS) WLAs (Annual) for the 478 significant permitted dischargers to meet TMDLs to attain the Chesapeake
BayWQS
Permit Name
TANEYTOWN
ELKTON
CENTREVILLE
BELTSVILLE USDA EAST
FORT DETRICK
NSWC-INDIAN HEAD
BRUNSWICK
DAMASCUS
THURMONT
ABERDEEN PROVING GROUNDS-
EDGEWOOD
ABERDEEN PROVING GROUNDS-
ABERDEEN
SENECA CREEK
FREEDOM DISTRICT
PISCATAWAY
BACK RIVER*
BACK RIVER*
ABERDEEN
SALISBURY
CUMBERLAND
PATAPSCO
FREDERICK
BOWIE
CAMBRIDGE
BROADNECK
PATUXENT
COX CREEK
MARLAY TAYLOR (PINE HILL RUN)
UPPER POTOMAC RIVER COMMISSION
FORT MEADE
NPDES ID
MD0020672
MD0020681
MD0020834
MD0020842
MD0020877
MD0020885
MD0020958
MDOQ20982
MD0021121
MD0021229
MD0021237
MD0021491
MD0021512
MD0021539
MD0021555
MD0021555
MD0021563
MD0021571
MDQ021598
MD0021601
MD0021610
MD0021628
MD0021636
MD0021644
MD0021652
MD0021661
MD0021679
MD0021687
MDQ021717
Jurisdiction
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
Segment ID
POTTF MD
ELKOH
CHSMH
ANATF MD
POTTF MD
POTTF MD
POTTF_MD
POTTF_MD
POTTF MD
BSHOH
CB1TF
POTTF MD
PATMH
PISTF
BACOH
PATMH
CB1TF
WICMH
POTTF MD
PATMH
POTTF MD
PAXTF
CHOMH2
CB3MH
PAXTF
PATMH
CB5MH MD
POTTF MD
PAXTF
TNEOS
WLA
(Ibs/yr)
13,400
37,156
6,091
7,553
24,364
6,091
17,055
18,273
12,182
36,547
34,110
316,738
42,638
365,467
1,583,691
609,112
48,729
103,549
182,734
889,304
97,458
40,201
98,676
73,093
91,367
182,734
73,093
79,109
54,820
TPEOS
WLA
(Ibs/yr)
1,005
2,787
457
566
1,827
457
1,279
1,371
914
2,741
2,558
21,380
3,198
16,446
79,185
30,456
3.655
7,766
13,705
66,698
7,309
3,015
7,401
5,482
6,853
13,705
5,482
30,401
4,112
TSS EOS
WLA (Ibs/yr)
100,503
278,669
45,683
56.647
182,734
45,683
127,914
137,050
91,367
274,100
255,827
2,375,537
319,784
2,741,004
11,877,684
4,568,340
365,467
776,618
1,370,502
6,669,776
730,934
301,510
740,071
548,201
685,251
1,370,502
548,201
1,982,660
411,151
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Table 9-4. Edge of Stream (EOS) WLAs (Annual) for the 478 significant permitted dischargers to meet TMDLs to attain the Chesapeake
Bay WQS
O
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IO
ISJ
O
Permit Name
PARKWAY
WESTERN BRANCH
HAVRE DE GRACE
HAGERSTOWN
ANNAPOLIS
BALLENGER CREEK
WESTMINSTER
MATTAWOMAN
HAMPSTEAD
MOUNT AIRY
JOPPATOWNE
POCOMOKE CITY
HURLOCK
SNOW HILL
MARLBORO MEADOWS
POOLESVILLE
KENT ISLAND
US NAVAL ACADEMY
TALBOT COUNTY REGION II
MARYLAND CORRECTIONAL INSTITUTE
BROADWATER
LEONARDTOWN
NORTHEAST RIVER
FRUITLAND
LITTLE PATUXENT
SOD RUN
SWAN POINT
PINEY ORCHARD
GEORGES CREEK
MAYO LARGE COMMUNAL
MARYLAND CITY
NPDES ID
MD0021725
MD0021741
MD0021750
MD0021776
MD0021814
MD0021822
MD0021831
MD0021865
MD0022446
MD0022527
MD0022535
MD0022551
MD0022730
MD0022764
MD0022781
MD0023001
MD0023485
MD0023523
MD0023604
MD0023957
MD0024350
MD0024767
MD0052027
MD0052990
MD0055174
MD0056545
MD0057525
MD0059145
MD0060071
MD0061794
MD0062596
Jurisdiction
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
Segment ID
PAXTF
PAXTF
CB1TF
POTTF MD
SEVMH
POTTF MD
POTTF MD
POTTF 'MD
GUNOH
PATMH
GUNOH
POCTF
NANOH
POCTF
PAXTF
POTTF_MD
CB3MH
SEVMH
EASMH
POTTF MD
CB4MH
POTMH MD
NORTF
WICMH
PAXTF
BSHOH
POTMH MD
PAXTF
POTTF MD
RHDMH
PAXTF
TNEOS
WLA
(Ibs/yr)
91,367
372,777
27,715
97,458
158,369
219,280
60,911
243,645
10,964
14,619
11,573
17,908
20,101
6,091
0
9,137
36,547
12,182
8,040
19,492
24,364
8,284
24,364
9,746
304,556
243,645
7,309
14,619
7,309
9,989
30,456
TPEOS
WLA
(Ibs/yr)
6,853
27,958
2,079
7,309
11,878
16,446
4,568
10,964
822
1,096
868
1,343
1,508
457
0
685
2,741
914
603
1,462
1,827
621
1,827
731
22,842
18,273
548
1,096
548
749
2,284
TSSEOS
WLA (Ibs/yr)
685,251
2,795,824
207,859
730,934
1,187,768
1,644,602
456,834
1,827,336
82,230
109,640
86,798
134,309
150,755
45,683
0
68,525
274,100
91,367
60,302
146,187
182,734
62,129
182,734
73,093
2,284,170
1,827,336
54,820
109,640
54,820
74,921
228,417
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Tab* »-4. Edg* of Stream (EOS) WLA» (Annual) for the 478 significant permitted dtechargw* to m*«t TMDU to attain tht CbasapMk*
BayWQS
r*fntit Main*
DORSEYRUN
CONOCOCHEAGUE
CELANESE
ALLEN FAMILY FOODS
WISE FOODS INC
EMPIRE KOSHER POULTRY-MIFFUNT
POPE & TALBOT WIS INC.
GOLD MILLS DYEHOUSE
APPLETON PAPER SPRINGMILL
MERCK & COMPANY
PPL MONTOUR LLC
NATIONAL GYPSUM COMPANY-MILTON
PLANT
P-H GLATFELTER COMPANY
PROCTOR & GAMBLE PAPER
PRODUCTS
OSRAM SYLVANIA PRODUCTS, INC.
CONSOLIDATED RAIL CORPORATION-
ENOLA
HEINZ PET FOODS
MOTTS INC
USFW-LAMAR NATIONAL FISH
HATCHERY
PAPETTI'S ACQUISTION INC (QUAKER
STATE FARMS)
PENNSYLVANIA FISH & BOAT
COMMISSION-BENNER SPRINGS
PENNSYLVANIA FISH & BOAT
COMMISSION-PLEASANT GAP
BLOSSBURG
MOUNT UNION BOROUGH
ROARING SPRING BOROUGH
NPDESID
MD0063207
MD0063S09
MD0063878
MD0067857
PA0007498
PA0007552
PA0007919
PA0008231
PA0008265
PA0008419
PA0008443
PA0008591
PA0008869
PA0008885
PA0009024
PA0009229
PA0009270
PA0009326
PA0009857
PA0009911
PAOO 10553
PAOO 10561
PA0020036
PA0020214
PA0020249
Jurisdiction
MD
MD
MD
MD
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
S*gm»mlD
PAXTF
POTTF MD
POTTF MD
CHOTF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
TNEOS
WLA
(Ibs/yr)
24,364
49.947
24,364
4.500
19,957
21,928
40.569
5,723
61.666
44.497
72.749
2,213
117,588
100,360
600.515
2.539
30.639
18.645
60.138
8.104
110,347
55.049
7.306
17,351
12,785
TPEOS
WLA
(lb*/yr)
1.827
3.746
1.827
370
898
740
1,941
198
7.367
11.748
1,200
106
6,821
5,441
1.577
93
1.449
729
1.919
532
2,285
1.591
974
2,314
1,705
TSS EOS
WLA(lb*/yr)
182.734
374.604
182,734
62.091
14.375
53.602
45.318
48.729
117.924
289,937
191,748
7,553
701,697
188,094
26.801
12.182
16.349
25.339
147,356
7,188
224,543
134,200
9,746
23,146
17,055
CB
cu
N
-------
Table 9-4. Edge of Stream (EOS) WLAs (Annual) for the 478 significant permitted dischargers to meet TMDLs to attain the Chesapeake
Bay WQS
"P
NJ
sr
NJ
NJ
O
o
Permit Name
MILTON MUNICIPAL AUTHORITY
LITITZ SEWAGE AUTHORITY
KULPMONT-MARION HEIGHTS JT MUN
BELLEFONTE BOROUGH
MCCONNELLSBURG STP
NORTHUMBERLAND BOROUGH
MIODLEBURG MUN AUTH
WAYNESBORO BOROUGH
MIODLETOWN
MONTGOMERY BOROUGH
WHITE DEER TOWNSHIP
GLEN ROCK SEW AUTH
DOVER TOWNSHIP SEWER AUTHORITY
FRANKLIN COUNTY AUTHORITY-
GREENCASTLE
MECHANICSBURG BOROUGH
MUNICIPAL
MANHEIM BOROUGH AUTHORITY
PINE GROVE BOROUGH AUTHORITY
NEW OXFORD MUNICIPAL FACILITY
MOUNT JOY
UTTLESTOWN BOROUGH
NEWPORT BORO MUN AUTH
DUNCANNON BORO
WILLIAMSBURG BOROUGH
GETTYSBURG MUNICIPAL AUTHORITY
MARYSVILLE MUNICIPAL AUTHORITY
DOVER BORO
WELLSBORO MUNICIPAL AUTHORITY
MARIETTA-DONEGAL JOINT AUTHORITY
ANNVILLE TOWNSHIP
NPDES ID
PA0020273
PA0020320
PA0020338
PA0020486
PA0020508
PA0020567
PA0020583
PA0020621
PA0020664
PA0020699
PA0020800
PA0020818
PA0020826
PA0020834
PA0020885
PA0020893
PA0020915
PA0020923
PA0021067
PA0021229
PA0021237
PA0021245
PA0021539
PA0021563
PA0021571
PA0021644
PA0021687
PA0021717
PA0021806
Jurisdiction
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
Segment ID
CB1TF
CB1TF
CB1TF
CB1TF
POTTF MD
CB1TF
CB1TF
POTTF MD
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
POTTF MD
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
POTTF MD
CB1TF
CB1TF
CB1TF
POTTF MD
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
TNEOS
WLA
(Ibs/yr)
80.040
70,319
9,132
58,812
10.959
20,548
8,219
29,223
40,182
15,525
10,959
10,959
146,117
17.351
38,565
21,847
27,397
35,057
27,945
18,265
7,306
13,516
9.132
44.748
22,831
7,306
46,029
13.698
13.698
TPEOS
WLA
(Ibs/yr)
8,329
9,376
1,218
7.842
1.461
2.740
1,096
3,896
5,358
2.070
1,461
1,461
19,482
2.314
5.065
2.776
3.653
4.354
3.726
2,435
974
1.802
1,218
5,966
3.044
974
4,871
1.826
1,826
TSS EOS
WLA (Ibs/yr)
83,326
93,802
12.182
78,453
14,619
27,410
10,964
38,983
53,601
20,710
14,619
14,619
194,914
19,491
50,678
I 27,775
I 36,1546"
43,563
37.277
24.364
9.746
18.030
12,182
59,692
30.455
9,746
48,729
18,273
18,273
n
tu
CD
>c
I
-------
Table 9-4. Edge of Stream (EOS) WLAs (Annual) for the 478 significant permitted dischargers to meet TMDLs to attain the Chesapeake
BayWQS
Permit Name
MANSFIELD BOROUGH
ADAMSTOWN BORO AUTH OF LANCAST
WESTFIELD BORO
NEW HOLLAND BOROUGH AUTHORITY
BEDFORD BOROUGH MUNICIPAL
AUTHORITY
MILLERSBURG BOROUGH AUTHORITY
ELIZABETHTOWN BOROUGH
HASTINGS AREA SA
MT. HOLLY SPRINGS BOROUGH
AUTHORITY
BERWICK MUNICIPAL AUTHORITY
TWIN BOROUGHS SANITARY
AUTHORITY
WRIGHTSVILLE BORO MUN AUTH
DANVILLE MUNICIPAL AUTHORITY
ASHLAND MUNICIPAL AUTHORITY
TRI-BORO MUNICIPAL AUTHORITY
NORTHEASTERN YORK COUNTRY
HIGHSPIRE
CUMBERLAND TWP AUTH (NORTH
PLANT)
CUMBERLAND TWP MUN AUTH
PENNFIELD FARMS INC (BC NATURAL
CHICKEN LLC)
PALMYRA BOROUGH AUTHORITY
MUNCY BOROUGH MUNICIPAL
AUTHORITY
NORTH MIDDLETON AUTH
MT. CARMEL MUNICIPAL SEWAGE
AUTHORITY
DILLSBURG BOROUGH AUTHORITY
NPDES ID
PA0021814
PA0021865
PA0021881
PA0021890
PA0022209
PA0022535
PA0023108
PA0023141
PA0023183
PA0023248
PA0023264
PA0023442
PA0023531
PA0023558
PA0023736
PA0023744
PA0024040
PA0024139
PA0024147
PA0024228
PA0024287
PA0024325
PA0024384
PA0024406
PA0024431
Jurisdiction
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
Segment ID
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
POTTF MD
POTTF MD
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
TNEOS
WLA
(Ibs/yr)
23,744
10,959
8,402
24,475
27,397
18,265
82,191
10,959
10,959
92,198
16,438
7,306
66,118
23,744
9,132
46,535
36,529
9,132
11,872
18,982
25,936
25,570
22,020
41,095
31,345
TPEOS
WLA
(Ibs/yr)
3,166
1,461
1,120
3,263
3,653
2,435
10,959
1,461
1,461
8,913
2,192
974
8,816
3,166
1,218
4,627
4,871
1,218
1,583
766
3,458
3>09
2,253
5,479
3,726
TSS EOS
WLA (Ibs/yr)
31,675
14,619
11,208
32,648
36,546
24,364
109,639
14,619
14,619
89,173
21,928
9,746
88,199
31,674
12,182
41,419
48,729
12,182
15,837
14,619
34,597
34,110
22,537
54,816
37,277
Ol
T8
Ol
CD
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Nl
tsj
D
n
8
3
or
ro
ro
O
-------
Table 9-4. Edge of Stream (EOS) WLAs (Annual) for the 478 significant permitted dischargers to meet TMDLs to attain the Chesapeake
Bay WQS
w
O
ro
n
m
I
Nl
O
Permit Name
UNION TWP STP
CURWENSVILLE MUNICIPAL AUTHORITY
UPPER ALLEN TOWNSHIP
SAXTON BORO MUN AUTH
LOCK HAVEN
CHAMBERSBURG BOROUGH
CARLISLE BOROUGH
WYOMING VALLEY
COLUMBIA
HUNTINGDON BOROUGH
UNIVERSITY AREA JOINT AUTHORITY
YORK CITY
LEWISTOWN BOROUGH
CLEARFIELD
LOWER LACKAWANNA VALLEY
LEMOYNE BOROUGH MUNICIPAL
AUTHORITY
DERRY TOWNSHIP MUNICIPAL
AUTHORITY
SCRANTON SEWER AUTHORITY
SUNBURY CITY MUNICIPAL AUTHORITY
MILLERSVILLE BOROUGH
NEW CUMBERLAND BOROUGH
AUTHORITY
TYRONE BOROUGH SEWER AUTHORITY
SWATARA TOWNSHIP
LANCASTER CITY
SPRINGETTSBURY TOWNSHIP
HANOVER BOROUGH
GREATER HA2ELTON
ALTOONA CITY AUTHORITY-EAST
NPDES ID
PA0024708
PA0024759
PA0024902
PA0025381
PA0025933
PA0026051
PA0026077
PA0026107
PA0026123
PA0026191
PA0026239
PA0026263
PA0026280
PA0026310
PA0026361
PA0026441
PA0026484
PA0026492
PA0026557
PA0026620
PA0026654
PA0026727
PA0026735
PA0026743
PA0026808
PA0026875
PA0026921
PA0027014
Jurisdiction
PA
PA
PA
PA
PA
PA
PA
PA
PA.
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
Segment ID
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
POTTF MD
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
TNEOS
WLA
(Ibs/yr)
11,872
13,698
20,091
7,306
90,192
124,199
134,277
584,467
36,529
73,058
164,381
474,880
51,470
82,191
109,588
46,270
91,668
365,292
76,711
33,790
22,831
166,231
115,367
620,248
273,969
83,441
216,739
146,117
TPEOS
WLA
(Ibs/yr)
1,583
1,826
2,679
974
9,132
16,560
17,047
77,929
4,871
9.741
21,918
63,317
6,863
10,959
14,612
5,784
12,225
48,706
10,228
4,505
3,044
21,918
15,342
77,318
36,529
10,959
27,092
19,482
TSS EOS
WLA (Ibs/yr)
15,837
18,273
26,801
9,746
91,366
165,677
170,550
779,657
48,729
97,457
219,279
633,471
68,659
109,639
146,186
50,873
122,309
487,286
102,330
45,074
30,455
219,279
153,495
77,318
365,464
109,639
216,842
194,914
n
ro
in
01
•a
00
QJ
-------
Table 9-4. Edge of Stream (EOS) WLAs (Annual) for the 478 significant permitted dischargers to meet TMDLs to attain the Chesapeake
BayWQS
Permit Name
ALTOONA CITY AUTHORITY-WEST
WILLIAMSPORT SANITARY AUTHORITY-
WEST
WILLIAMSPORT SANITARY AUTHORITY-
CENTRAL
LACKAWANNA RIVER BASIN SEWER
AUTHORITY
LACKAWANNA RIVER BASIN SEWER
AUTHORITY
LACKAWANNA RIVER BASIN SEWER
AUTHORITY
BLOOMSBURG MUNICIPAL AUTHORITY
LOWER ALLEN TOWNSHIP AUTHORITY
HARRISBURG SEWERAGE AUTHORITY
LEBANON CITY AUTHORITY
SHAMOKIN-COAL TOWNSHIP JOINT
SANITARY AUTHORITY
EPHRATA BOROUGH WWTP
PINE CREEK MUNICIPAL AUTHORITY
BROWN TOWNSHIP MUNICIPAL
AUTHORITY
FT INDIANTOWN GAP
TROY BORO
MARTINSBURG
MIFFLINBURG BOROUGH MUNICIPAL
CLARKS SUMMIT-SOUTH ABINGTON
JOINT AUTHORITY
EMPORIUM BOROUGH (MID-CAMERON
AUTHORITY)
JERSEY SHORE BOROUGH
GALLITZIN BORO
NPDES ID
PA0027022
PA0027049
PA0027057
PA0027065
PA0027081
PA0027090
PA0027171
PA0027189
PA0027197
PA0027316
PA0027324
PA0027405
PA0027553
PA0028088
PA0028142
PA0028266
PA0028347
PA0028461
PA0028576
PA0028631
PA0028665
PA0028673
Jurisdiction
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
Segment ID
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
TNEOS
WLA
(Ibs/yr)
164,381
77,547
153,423
109,587
12,786
127,852
78,855
114,354
688,575
146,117
127,852
79,049
23,744
10,959
24,353
7,306
12,785
25,570
45,662
17,100
19,178
7,306
TPEOS
WLA
(Ibs/yr)
21,918
9,564
20,456
14,612
1,705
17,047
10.447
15,221
91,810
19,482
17,047
9,881
3,166
1,461
3,044
974
1,705
3,409
6,088
2,140
2,557
974
TSS EOS
WLA (Ibs/yr)
219,279
95,508
204,660
146,186
17,055
170,550
104,523
152,277
918,533
194,914
170,550
92,584
31,674
14,619
24,364
9,746
17,055
34,110
60,911
24,364
25,582
9,746
n
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et
QJ
o
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3
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Table 9-4. Edge of Stream (EOS) WLAs (Annual) for the 478 significant permitted dischargers to meet TMDLs to attain the Chesapeake
BayWQS
U)
ro
Ln
O
o>
n
n>
o-
ra
NJ
O
Permit Name
KELLY TOWNSHIP MUNICIPAL
AUTHORITY
RALPHO TWP MUN AUTH
QUARRYVILLE STP
GREENFIELD TWP MUN AUTH
SOUTH MOUNTAIN RESTORATION CEN
PA DEPT OF PUBLIC WELFARE
DALLAS SCI
FRANKLIN COUNTY GENERAL AUTH
(SOUTH PATROL RD)
SHIPPENSBURG BOROUGH AUTHORITY
GRANVILLE TWP
DCNR-BALD EAGLE STATE PARK
LOGAN TOWNSHIP-GREENWOOD AREA
DUNCANSVILLE
TOWANDA MUNICIPAL AUTHORITY
TYSON FOODS
FARMER'S PRIDE INC
STEWARTSTOWN BOROUGH
GALETON BORO AUTH
PFBC HUNTSDALE
PENN TOWNSHIP
EVERETT BORO AREA MA
MOSHANNON VALLEY JOINT SANITARY
AUTHORITY
DEFENSE DISTRIBUTION DEPOT
SUSQUEHANNA
EAST PENNSBORO SOUTH TREATMENT
PLANT
SUSQUEHANNA AQUACULTURE INC
BURNHAM BOROUGH
NPDES ID
PA0028681
PA0028738
PA0028886
PA0029106
PA0029297
PA0029432
PA0030139
PA0030597
PA0030643
PA0032051
PA0032492
PA0032557
PA0032883
PA0034576
PA0035092
PA0035157
PA0036269
PA0036820
PA0037141
PA0037150
PA003771 1
PA0037966
PA0038385
PA0038415
PA0038598
PA0038920
Jurisdiction
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
Segment ID
CB1TF
CB1TF
CB1TF
CB1TF
POTTF_MD
CB1TF
CB1TF
POTTF MD
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
TNEOS
WLA
(Ibs/yr)
68,492
13,132
7,306
14,612
9,132
10,959
9,741
9,132
60,273
15,196
8,219
12,785
22,228
21,187
27,397
16,438
13,516
9,132
53,512
81,811
15,890
31,634
9,132
67,579
54,007
11,689
TPEOS
WLA
(Ibs/yr)
9,132
1,751
974
1,948
1,218
1,461
1,218
1,218
8,036
1,899
1,096
1,705
2,963
2,825
559
1,370
1,802
1,218
2,804
10,228
2,119
4,218
1,218
9,011
3,530
1,559
TSS EOS
WLA (Ibs/yr)
91,366
17,518
9,746
19,491
12,182
9,624
10,964
12,182
80,402
12,182
10,964
17,055
29,651
28,263
36,547
21,928
18,030
12,182
336,230
102,330
21,197
42,199
12,182
90,148
161,293
15,593
n
CO
su
CD
tu
O
-------
Table 9-4. Edge of Stream (EOS) WLAs (Annual) for the 478 significant permitted dischargers to meet TMDL* to attain the Chesapeake
BayWQS
o
Oi
•O
ft
o>
jc
n
OS
Permit Name
PENNSYLVANIA FISH & BOAT
COMMISSION-BELLEFONTE
LANCASTER AREA SEWER AUTHORITY
TREMONT MUNICIPAL AUTHORITY
NEW FREEDOM WTP
HOLLIDAYSBURG REGIONAL
LYKENS BOROUGH
VALLEY JOINT SEW AUTH
WESTERN CLINTON COUNTY
MUNICIPAL AUTHORITY
PENNSYLVANIA FISH & BOAT
COMMISSION-UPPER SPRING
SOUTH MIDDLETON TOWNSHIP
MUNICIPAL AUTHORITY
LEWISBURG AREA JOINT SANITARY
AUTHORITY/COLLEGE P
HANOVER FOODS CORP
MOUNT AINTOP AREA
PORTER TOWER JOINT MUNICIPAL
AUTHORITY
ST. JOHNS
REPUBLIC SERVICES OF PA LLC
CAN-DO INC
SHICKSHINNY BORO SA
MONTROSE MA
ABINGTON TWP SUPERVISORS
LITTLE WASHINGTON WW CO
SCHUYLKILL CO MA
FRACKVILLE AREA MA
KBM REGIONAL AUTH (NEW)
MAHANOY CITY
NPOES ID
PA0040835
PA0042269
PA0042951
PA0043257
PA0043273
PA0043S75
PA0043681
PA0043693
PA0044032
PA0044113
PA0044661
PA0044741
PA0045985
PA0046272
PA0046388
PA0046680
PA0060046
PA006013S
PA0060801
PA0061034
PA0061590
PA0062201
PA0062219
PA0064025
PA0070041
Jurisdiction
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
Segment ID
CB1TF
CB1TF
CB1TF •
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
TNEOS
WLA
(Ibs/yr)
78.988
273.969
9.132
42.009
109,587
7,488
41,095
16,438
7,000
29,322
44.200
26.385
75,981
7,854
40,182
40,803
18,265
8,219
14,977
9,132
24.073
10,959
25,570
13,637
25,205
TPEOS
WLA
re
o
re
I
to
-------
Table 9-4. Edge of Stream (EOS) WLAs (Annual) for the 478 significant permitted dischargers to meet TMDLs to attain the Chesapeake
Bay WQS
n
o
»-«
O I
Permit Name
SHENANDOAH MUNICIPAL SEWAGE
AUTHORITY
CAERNARVON TWP STP
WASHINGTON TOWNSHIP MUNICIPAL
HAMPDEN TOWNSHIP SEWER
AUTHORITY
NORTHERN LANCASTER CO AUTH J
ANTRIM TOWNSHIP
NORTHERN LEBANON CO AUTH
ST THOMAS TWP MUN AUTH
SALISBURY TWP
EASTERN YORK COUNTY SEWER AUTH
FAIRVIEW TOWNSHIP
WEST EARL SEW AUTH
DERRY TWP MUN AUTH - SOUTHWEST
FAIRVIEW TOWNSHIP
NEWBERRY TOWNSHIP
SILVER SPRING TOWNSHIP
NORTHWESTERN LANCASTER CNTY
AUTH
CONEWAGO TWP SEW AUTH
WEST HANOVER
SPRINGFIELD TWP SEW AUTH - HOL
EPHRATA BORO AUTH #2
CHESTNUT RIDGE AREA JMA
NEW MORGAN STP
LOWER PAXTON WET WEATHER STP
FREEDOM TOWNSHIP WATER&SEWER
AUTHORITY
PATTON BORO STP
FURMAN FOODS
NPDES ID
PA0070386
PA0070424
PA0080225
PA0080314
PA0080438
PA0080519
PA0080748
PA0081001
PA0081574
PA0081591
PA0081868
PA0081949
PA0082392
PA0082589
PA0083011
PA0083593
PA0084026
PA0084425
PA0085511
PA0086860
PA0087181
PA0087661
PA0088048
PA0088633
PA01 10361
PAD 11 0469
PA0110540
Jurisdiction
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
Segment ID
CB1TF
CB1TF
POTTF MD
CB1TF
CB1TF
POTTF MD
CB1TF
POTTF MD
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
TNEOS
WLA
(Ibs/yr)
36,529
12,785
35,433
101,997
8,219
21,918
7,306
7,306
13,150
10,959
13,333
8,219
10,959
9,132
23,744
21,918
14,612
9,132
16.496
12,785
54,550
12.877
9,132
45,662
10,959
9.863
45450
TPEOS
WLA
(Ibs/yr)
4,871
1,705
4,724
12,359
1,096
2,922
974
974
1,643
1,461
1,778
1,096
1.461
1,218
3,166
2,922
1,827
1.218
1.900
1,704
6.818
1,717
1,218
6,088
1,461
1.315
1,624
TSS EOS
WLA (Ibs/yr)
48,729
17,055
47,267
117,436
10,964
29,237
9,746
9,746
14,131
14,619
17,786
10,964
14,619
12,182
31,674
29.237
15,837
12,182
1,900
17,055
56,038
17,177
12,182
60,911
14.619
13.157
5,847
o
n
03
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-------
Tabto 9-4. Edge of Stream (EOS) WLA» (Annual) for the 478 tignificant permitted dtechargere to meet TMDU to attain the Chesapeake
BayWQS
Permit Name
EASTERN SNYDER COUNTY REGIONAL
AUTH
MID-CENTRE COUNTY AUTH
TAYLOR PACKING CO INC
PENNSYLVANIA FISH & BOAT
COMMISSION-TYPLERSV1LLE
ELKLAND MUNICIPAL AUTHORITY
GREGG TOWNSHIP
HUGHESVILLE-WOLF TWP JOINT SEW
WEST BRANCH SA
LYCOMING CO WATER & SEWER AUTH
NORTH CODORUS TWP
PILGRIM'S PRIDE • ALMA
DUPONT-WAYNESBORO
MERCK & COMPANY INC.-STONEWAU
PLANT-ELKTON
PILGRIMS PRIDE-HINTON
GIANT REFINERY-YORKTOWN
SMURFIT STONE
OMEGA PROTEIN INC
TYSON FOODS. INC.-TEMPERANCEVILLE
STRASBURG
VINT HILL FARMS STATION WWTP
BERRYVILLE
KILMARNOCK
NAVAL SURFACE WARFARE CENTER-
DAHLGREN
GORDONSVILLE
WARRENTON
ONANCOCK
CAPE CHARLES
NPOESID
PAD 11 0582
PA01 10965
PA01 11759
PA01 12127
PAD 11 3298
PA0114821
PA01 14961
PA0205869
PA0209228
PA0247391
VA0001961
VA0002160
VA0002178
VA0002313
VA0003018
VA0003115
VA0003867
VA0004049
VA0020311
VA0020460
VA0020532
VA0020788
VA0021067
VA0021105
VA0021172
VA0021253
VA0021288
Jurisdiction
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
Segment ID
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
POTTF MD
POTTF MD
POTTF MD
POTTF MD
MOBPH
PMKOH
CB5MH VA
POCMH VA
POTTF MD
POTTF VA
POTTF MD
CB5MH VA
POTMH VA
PMKTF
RPPTF
CB7PH
CB7PH
TNEOS
WLA
(Ibs/yr)
51,141
18.265
14.612
63.339
10.277
23,013
12,329
16,438
27.397
13.394
18.273
78.941
43,835
27.410
167,128
259.177
21.213
22,842
11,939
11.573
8,528
6,091
6.578
17,177
30.456
9.137
6.091
TPEOS
WLA
(lb«/yr)
6,819
2.435
1.218
2.382
1.285
3.068
1.644
2.192
3.653
1,674
914
1,009
4,384
1.371
17,689
56.038
1.591
1,142
895
868
640
457
658
1,145
2,284
685
457
TSS EOS
WLA (Ibs/yr)
68.220
24,364
19,492
316,738
13,400
30,699
16,446
21.928
36,546
13,400
61.028
88.330
2.168,100
66.649
160.600
13,030,500
352.836
60.955
89.539
86.798
63,957
45,683
65.784
85,885
228,417
68,525
45,683
o
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-------
Table 9-4. Edge of Stream (EOS) WLAs (Annual) for the 478 significant permitted dischargers to meet TMDLs to attain the Chesapeake
Bay WQS
O
Permit Name
ORANGE
WEYERS CAVE STP
PURCELLVILLE
NEW MARKET STP
HAYNESVILLE CORRECTIONAL CENTER
DALE CITY #8
DALE CITY #1
MASSANUTTEN PUBLIC SERVICE STP
ASHLAND
UPPER OCCOQUAN SEWAGE
AUTHORITY
H.L MOONEY
FREDERICKSBURG
ARLINGTON
WAYNESBORO
ALEXANDRIA
FISHERSVILLE
NOMAN M. COLE JR. POLLUTION
CONTROL PLANT
MASSAPONAX
ROUND HILL WWTP
URBANNA
COLONIAL BEACH
MT JACKSON STP
WOODSTOCK
DAHLGREN (DAHLGREN SANITARY
DISTRICT)
WARSAW
SHORE HOSPITAL
QUANTICO-MAINSIDE
STONEY CREEK STP
NPDES ID
VA0021385
VA0022349
VA0022602
VA0022853
VA0023469
VA0024678
VA0024724
VA0024732
VA0024899
VA0024988
VA0025101
VA0025127
VA0025143
VA00251S1
VA0025160
VA002S291
VA0025364
VA0025658
VA0026212
VA0026263
VA0026409
VA0026441
VA0026488
VA0026514
VA0026891
VA0027537
VA0028363
VA0028380
Jurisdiction
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
Segment ID
RPPTF
POTTF MD
POTTF MD
POTTF MD
RPPMH
POTTF VA
POTTF VA
POTTF MD
PMKTF
POTTF VA
POTTF_VA
RPPTF
POTTF VA
POTTF MD
POTTF VA
POTTF MD
POTTF VA
RPPTF
POTTF_MD
RPPMH
POTMH VA
POTTF MD
POTTF MD
POTMH VA
RPPMH
CB7PH
POTOH VA
POTTF MD
TNEOS
WLA
(Ibs/yr)
36,547
6,091
18,273
6,091
2,802
42,029
42,029
18.273J
36,547
1,315,682
219,280
54,820
365,467
48.729
500,690
48.729
612.158
97,458
9,137
1,218
18,273
8,528
24.364
9,137
3,655
1,218
20,101
7.309
TPEOS
WLA
(Ibs/yr)
2,741
457
1,371
457
210
2,522
2,522
1,371
2,436
16,446
13.157
4.112
21,928
3.655
29.932
3,655
36,729
7,309
685
91
1,827
640
1.827
914
274
91
1.206
548
TSS EOS
WLA (Ibs/yr)
274.100
45,683
137.050
45.683
21,014
420,287
420,287
137.050
182,734
4,933,807
2,192,803
411.151
3.654,672
365,467
4,988,627
365,467
6,121.576
730.934
68.525
9.137
182.734
63.957
182,734
91,367
27,410
9,137
201,007
54,820
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Table 9-4. Edge of Stream (EOS) WLAs (Annual) for the 478 significant permitted dischargers to meet TMDLs to attain the Chesapeake
BayWQS
Permit Name
MATHEWS COURTHOUSE
DOSWELL
MARSHALL WWTP
FORT A.P. HILL (WILCOX CAMP SITE)
HARRISONBURG-ROCKINGHAM (NORTH
RIVER REGIONAL)
REEDVILLE
AQUIA
CULPEPER
LURAY
FRONT ROYAL
MIDDLE RIVER
FWSA OPEQUON
STUARTS DRAFT
TANGIER ISLAND
FMC
PURKINS CORNER STP
TAPPAHANNOCK
MONTROSS - WESTMORELAND
COORS SHENANDOAH BREWERY
CAROLINE COUNTY REGIONAL
PARKINS MILL
WEST POINT
LITTLE FALLS RUN
REMINGTON REGIONAL
GEORGE'S CHICKEN INC
BEAR ISLAND PAPER CO.
SOUTH WALES STP
HRSD-YORK
WILDERNESS SHORES
OAKLAND PARK STP
NPDES ID
VA0028819
VA0029521
VA0031763
VA0032034
VA0060640
VA0060712
VA0060968
VA0061590
VA0062642
VA0062812
VA0064793
VA0065552
VA0066877
VA0067423
VA0068110
VA0070106
VA0071471
VA0072729
VA0073245
VA0073504
VA0075191
VA0075434
VA0076392
VA0076805
VA0077402
VA0077763
VA0080527
VA0081311
VA008341 1
VA0086789
Jurisdiction
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
Segment ID
MOBPH
PMKTF
RPPTF
RPPTF
POTTF MD
CB5MH VA
POTOH VA
RPPTF
POTTF MD
POTTF MD
POTTF MD
POTTF MD
POTTF_MD
POCMH VA
RPPTF
POTMH VA
RPPMH
RPPMH
POTTF MD
MPNTF
POTTF MD
MPNOH
RPPTF
RPPTF
POTTF MD
PMKTF
RPPTF
MOBPH
RPPTF
POTOH VA
TNEOS
WLA
(Ibs/yr)
1,827
18,273
7,797
6,457
253,391
2,436
73,093
73,093
19,492
48,729
82,839
121,851
48,729
1,218
65,784
1,096
9,746
1,584
54,820
9,137
60,911
10,964
97,458
30,456
31,065
47,328
10,964
274,100
15,228
1,706
TPEOS
WLA
(Ibs/yr)
122
1,218
585
484
19,004
183
4,386
5,482
1,462
3,655
6,213
11,512
3,655
91
4,934
110
731
119
4,112
609
4,568
731
7,309
2,284
1,553
10,233
822
18,273
1,142
128
TSS EOS
WLA (Ibs/yr)
9,137
91,367
58,475
48,424
1,900,429
18,273
730,934
548,201
146,187
365,467
621,294
1,151,222
365,467
9,137
493,381
10,964
73,093
11,878
184,690
45,683
456,834
54,820
730,934
228,417
104,390
383,741
82,230
1,370,502
114,209
12,791
O)
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Table 9-4. Edge of Stream (EOS) WLAs (Annual) for the 478 significant permitted dischargers to meet TMDLs to attain the Chesapeake
Bay WQS
o
n>
3
g"
Permit Name
PARHAM LANDING WWTP
HAYMOUNT STP
HOPYARD FARMS STP
TOTOPOTOMOY
MOUNTAIN RUN STP
SIL MRRS
NORTH FORK REGIONAL WWTP
RAPIDAN STP
BROAD RUN WRF
FAIRVIEW BEACH
LEESBURG
PILGRIM'S PRIDE
VIRGINIA ELECTRIC & POWER
LEETOWN SCIENCE CENTER
MOOREFIELD
ROMNEY
PETERSBURG
CHARLES TOWN
MARTINSBURG
KEYSER
SHEPHERDSTOWN
WARM SPRINGS PSD
FORT ASHBY PSD
HESTER INDUSTRIES, INC.
BERKELEY COUNTY PSSD***
REEDS CREEK HATCHERY
SPRING RUN HATCHERY
THE CONSERVATION FUND
FRESHWATER INST
NPDES ID
VA0088331
VA0089125
VA0089338
VA0089915
VA0090212
VA0090263
VA0090328
VA0090948
VA0091383
VA0092134
VA0092282
WV0005495
WV0005525
WV0005649
WV0020150
WV0020699
WV0021792
WV0022349
WV0023167
WV0024392
WV0024775
WV0027707
WV0041521
WV0047236
WV0082759
WV01 11821
WV01 12500
WV0116149
Jurisdiction
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
WV
WV
WV
WV
WV
WV '
WV
WV
WV
WV
WV
WV
WV
WV
WV
WV
WV
Segment ID
PMKOH
RPPTF
RPPTF
PMKTF
RPPTF
POTTF MD
POTTF MD
RPPTF
POTTF MD
POTOH VA
POTTF MD
POTTF MD
POTTF MD
POTTF MD
POTTF MD
POTTF MD
POTTF MD
POTTF MD
POTTF MD
POTTF MD
POTTF MD
POTTF MD
POTTF MD
POTTF MD
POTTF MD
POTTF MD
POTTF MD
POTTF MD
TNEOS
WLA
(Ibs/yr)
36,547
11,695
6,091
182,734
0
23,390
9,137
7,309
134,005
1,827
121,822
13,096
0
18,273
9,137
7,614
20,558
26,649
45,683
36,547
6,091
26,496
7,614
7,614
89,844
26,298
65,480
15,380
TPEOS
WLA
(Ibs/yr)
2,436
877
457
12,182
0
1,754
685
548
3,350
183
9,137
1,310
0
1,827
914
761
2,056
2,665
4,568
3,655
609
2,650
761
761
8,984
2,630
6,548
1,538
TSS EOS
WLA (Ibs/yr)
182,734
87,712
45,683
913,668
0
175,424
68,525
54,820
1,005,035
18,273
913,668
13,096
0
18,273
9,137
7,614
20,558
26,649
45,683
36,547
6,091
26,496
7,614
7,614
89,844
26,298
65,480
15,380
n
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en
QJ
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cu
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Table 9-4. Edge of Stream (EOS) WLAs (Annual) for the 478 significant permitted dischargers to meet TMDLs to attain the Chesapeake
Bay WQS
Permit Name
NY Significant WWTP Aggregate
KRAFT FOODS, INC.
KRAFT FOODS GLOBAL
ADDISON (V)
HAMILTON (V)
GREENE (V) WWTP
NORWICH
BATH (V)
SHERBURNE (V) WWTP
ALFRED (V)
OWEGO (T) #1
CANISTEO (V) STP
COOPERSTOWN
HORNELL (C)
ERWIN (T)
BINGHAMTON-JOHNSON CITY JOINT
BOROUGH
PAINTED POST (V)
CORNING (C)
OWEGO #2
CORTLAND (C)
ENDICOTT (V)
OWEGO (V)
SIDNEY (V)
WAVERLY (V)
ONEONTA (C)
RICHFIELD SPRINGS (V)
ELMIRA / CHEMUNG CO. SD #2
LAKE STREET/CHEMUNG COUNTY SD #1
CHENANGO NORTHGATE WWTP
NPDES ID
Including 28 NPDES
listed below
NY0004189
NY0004308
NY0020320
NY0020672
NY0021407
NY0021423
NY0021431
NY0021466
NY0022357
NY0022730
NY0023248
NY0023591
NY0023647
NY0023906
NY0024414
NY0025712
NY0025721
NY0025798
NY0027561
NY0027669
NY0029262
NY0029271
NY0031089
NY0031151
NY0031411
NY0035742
NY0036986
NY0213781
Jurisdiction
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
Segment ID
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
CB1TF
TNEOS
WLA
(Ibs/yr)
1,545.956
TPEOS
WLA
(Ibs/yr)
104,612
•
-
TSS EOS
WLA (Ibs/yr)
3.185,071
OJ
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Ul
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Table 9-4. Edge of Stream (EOS) WLAs (Annual) for the 478 significant permitted dischargers to meet TMDLs to attain the Chesapeake
Bay WQS
f
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O
Permit Name
VA James River Significant PS Aggregate
R.J. REYNOLDS (BROWN & WILLIAMSON)
GEORGIA PACIFIC CORPORATION
JH MILES
WESTVACO CORPORATION-COVINGTON
HALL
BWXT
TYSON FOODS, INC.
DOMINION VIRGINIA POWER-
CHESTERFIELD
DUPONT-SPRUANCE
LEES COMMERCIAL CARPET
HONEYWELL
GREIF BROS CORP-RIVERVILLE
CREWE STP
DOC Powhatan CC
BUENA VISTA
CLIFTON FORGE
LAKE MONTICELLO STP
LYNCHBURG
FALLING CREEK
SOUTH CENTRAL
MOORES CREEK-RIVANNA AUTHORITY
COVINGTON
PHILLIP MORRIS-PARK 500
LOW MOOR
AMHERST TOWN STP
PROCTORS CREEK
RICHMOND
HENRICO COUNTY
NPDES ID
Including 39 NPDES
listed below
VA0002780
VA0003026
VA0003263
VA0003646
VA0003697
VA0004031
VA0004146
VA0004669
VA0004677
VA0005291
VA0006408
VA0020303
VA0020699
VA0020991
VA0022772
VA0024945
VA0024970
VA0024996
VA0025437
VA0025518
VA0025542
VA0026557
VA0027979
VA0031321
VA0060194
VA0063177
VA0063690
Jurisdiction
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
Segment ID
JMSTF2
JMSTF2
JMSPH
JMSTF2
JMSTF2
CHKOH
JMSTF2
JMSTF2
JMSTF2
JMSTF1
JMSTF2
APPTF
JMSTF2
JMSTF2
JMSTF2
JMSTF2
JMSTF2
JMSTF2
APPTF
JMSTF2
JMSTF2
JMSTF1
JMSTF2
JMSTF2
JMSTF2
JMSTF2
JMSTF2
TN EOS TP EOS
WLA WLA
(Ibs/yr) (Ibs/yr)
8.968,864
545.558
TSS EOS
WLA (Ibs/yr)
79.804.603
O
QJ
T3
n
00
-------
Table 9-4. Edge of Stream (EOS) WLAs (Annual) for the 478 significant permitted dischargers to meet TMDLs to attain the Chesapeake
Bay WQS
Permit Name
HOPEWELL
HRSD-ARMY BASE
HRSD-BOAT HARBOR
HRSD-CHESAPEAKE/ELI2ABETH
HRSD-JAMES RIVER
HRSD-VIP
HRSD-NANSEMOND
HRSD-WILLIAMSBURG
FARMVILLE
LEXINGTON-ROCKBRIDGE REGIONAL
STP
CHICKAHOMINY
ALLEGHANY CO. LOWER JACKSON
NPDES ID
VA0066630
VA0081230
VA0081256
VA0081264
VA0081272
VA0081281
VA0081299
VA0081302
VA0083135
VA0088161
VA0088480
VA0090671
Jurisdiction
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
Segment ID
JMSTF1
JMSPH
JMSPH
LYNPH
JMSMH
ELIPH
JMSPH
JMSOH
APPTF
JMSTF2
CHKOH
JMSTF2
TNEOS
WLA
(Ibs/yr)
'
TPEOS
WLA
(Ibs/yr)
TSS EOS
WLA (Ibs/yr)
n
rt>
in
EU
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ro
O)
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* Back River WWTP discharges into two segments BACOH and PATMH
** Blue Plains treats wastewater from DC, MD and VA, but is listed once in this table as a plant located in DC
*** BERKELEY COUNTY PSSD WV0082759 includes four facilities under the same permit.
Note: Gray shading indicates significant permitted dischargers that are part of a larger aggregate WLA.
O
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Chesapeake Bay TMDL
SECTION 10. IMPLEMENTATION AND ADAPTIVE
MANAGEMENT
10.1 FUTURE GROWTH
As an assumption of the Chesapeake Bay TMDL, EPA expects Chesapeake Bay jurisdictions to
account for and manage new or increased loadings of nitrogen, phosphorus, and sediment.
10.1.1 Designating Target Loads for New or Increased Sources
Where the TMDL does not provide a specific allocation to accommodate new or increased
loadings of nitrogen, phosphorus, or sediment, a jurisdiction may accommodate such new or
increased loadings only through a mechanism allowing for quantifiable and accountable offsets
of the new or increased load in an amount necessary to implement the TMDL and applicable
WQS in the Chesapeake Bay and its tidal tributaries. Therefore, the Chesapeake Bay TMDL
assumes, and EPA expects, that the jurisdictions will accommodate new or increased loadings of
nitrogen, phosphorus, or sediment that do not have a specific allocation in the TMDL with
appropriate offsets supported by credible and transparent offset programs subject to EPA
oversight.
10.1.2 Offset Programs
EPA expects that new or increased loadings ot nitrogen, phosphorus, and sediment in the
Chesapeake Bay watershed that are not specifically accounted for in the TMDL's WLA or LA
will be offset by loading reductions and credits generated by other sources under programs that
are consistent with the definitions and common elements described in Appendix S. These
definitions and common elements are important to ensure that offsets are achieved through
reliable pollution controls and that the goals of the Chesapeake Bay TMDL are met.
EPA expects the jurisdictions to develop offset programs that are credible, transparent, consistent
with the definitions and common elements set out in Appendix S, and subject to EPA and public
oversight. Any such offsets are expected to account for the entire delivered nitrogen, phosphorus,
or sediment load after accounting for location of the sources, delivery factors affecting pollutant
fate and transport, equivalency of pollutants, and the certainty of any such reductions. In
addition, such offsets may not cause an exceedance of local WQS or local TMDLs. The offsets
are to be in addition to reductions already needed to meet the allocations in the TMDL and must
be consistent with applicable federal and state laws and regulations.
For nonpoint sources, this assumption and expectation is based on the fact that any new or
increased nonpoint source loadings not accounted for in the TMDL's LA will have to be offset
by appropriate reductions from other sources if the TMDL's pollutant loading cap and applicable
WQS are to be met. For permitted point sources, the assumption and expectation also is based on
the statutory and regulatory requirements that effluent limits for any such discharges be derived
from and comply with all applicable WQS and be consistent with the assumptions and
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Chesapeake Bay TMDL
requirements of any available WLAs [CWA sections 301(b)(l)(C), 303(d); 40 CFR
122.44(d)(l)(vii)(A)&(B)J.
In addition, CWA section 117(g) authorizes EPA to ensure that management plans are developed
and implementation is begun to achieve and maintain the Bay's nutrient goals. If jurisdictions
authorize new or increased loadings without a specific TMDL allocation, an offset is a necessary
component of any management plan designed to meet those goals. Accordingly, the Bay TMDL
assumes that new point source dischargers, without an allocation in the TMDL (or in other
words, with a zero allocation), will find offsets large enough to compensate for their entire
loading. The TMDL similarly assumes that point source dischargers that increase pollution
loading will find offsets large enough to compensate for the entire increase in their loading and
to meet their Water Quality Based Effluent Limit (WQBEL) consistent with the WLA in the
TMDL. In the case of new or increased loading from sources other than permitted point source
dischargers, jurisdictions are expected to estimate loadings and ensure offsets that fully
compensate for this estimated increase in pollutant load.
Although EPA assumes that there can legitimately be some flexibility in the design and content
of Bay jurisdiction offset programs, EPA encourages and expects that the jurisdictions will
generally develop and implement programs for offsetting new and increased loadings consistent
with the definitions and common elements described in detail in Appendix S. EPA also
encourages and expects jurisdictions with existing trading programs that address new or
increased loadings (such as several jurisdictions have), to ensure that their programs address new
or increased loads consistent with the definitions and common elements in Appendix S.
10.1.3 Additional Offset Program Features
The jurisdictions also may consider using the following features to build their offset programs
for new or increased loadings of nitrogen, phosphorus, and sediment:
Met Improvement Offsets: For purposes of the Bay TMDL, this means an offset at a ratio greater
than merely accounting for the entire new or increased load. The jurisdiction's offset program
would need to provide the authority and procedures for invoking such a provision. This tool
might be considered as a means to accelerate load reductions where a jurisdiction is not on a
schedule to ensure that nitrogen, phosphorus, and sediment controls are in place by 2017 and
2025 to meet interim and final target loads, respectively. This may be determined based on an
EPA evaluation of a jurisdiction's progress on its WIP and 2-year milestones, as discussed in
EPA's December 29, 2009 letter (USEPA 2009d). Net improvement offsets also might be
considered, in the case of permitted point sources, to offset new or increased loads from nonpoint
sources or from point sources not expected to be permitted.
Aggregated Programmatic Credits: For purposes of the Bay TMDL, this means defining a
programmatic solution for over-control of nitrogen, phosphorus or sediment beyond the basic
WIP strategies to achieve the TMDL allocation. In essence, it is an aggregation of credits from
reductions by a class or subclass of sources where such reductions have been achieved by the
jurisdiction or another duly authorized body. The jurisdiction may consider making such credits
available to offset new or increased loadings. In some circumstances, such class reductions also
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Chesapeake Bay TMDL
could be applied as a reallocation of loadings under the TMDL. Such reallocation may require
modification of the TMDL.
Reserve-Offset Hybrid: For purposes of the Bay TMDL, this applies where a jurisdiction reserves
a portion of its allocations for future growth and, once that allocation is depleted, uses an offset
program as described herein.
10.1.4 EPA's Oversight Role of Jurisdictions' Offset Programs
EPA encourages jurisdictions to consult with EPA throughout the development of their offset
programs to facilitate alignment with the CWA and the Bay TMDL. EPA has various oversight
responsibilities under the CWA. MOUs for authorization of jurisdictions' NPDES programs, and
the TMDL/Executive Order 13508, including approval of revisions to WQS, review of NPDES
permits, and provisions for reviewing and making recommendations regarding revisions to a
jurisdiction's water quality management plans through the continuing planning process.
EPA intends to maintain regular oversight of jurisdictions' offset programs through periodic
audits and evaluations. EPA will report its findings to the respective jurisdiction. EPA's first
such review of jurisdictional offset and trading programs will take place in calendar year 2011.
EPA expects that the findings of this evaluation will inform offset and trading provisions
included in the jurisdictions' Phase II WIPs. Such oversight generally will be conducted on a
programmatic basis, not an individual offset basis. EPA reserves its authority, however, to
review any individual offset (including an NPDES permit containing an offset) and to comment
on, object to, or issue the permit as needed if EPA determines that the offset is not consistent
with the Clean Water Act or EPA's regulations. When questions or concerns arise, EPA will use
its oversight authorities to ensure that offset programs are fully consistent with the CWA and its
implementing regulations. EPA recognizes the value of implementing a strategy for offsets that,
wherever possible, is consistent among the jurisdictions to increase credibility, scalability, and
broader regional implementation such as interstate trading.
10.2 WATER QUALITY TRADING
EPA recognizes that a number of Bay jurisdictions already are implementing water quality
trading programs. EPA supports implementation of the Bay TMDL through such programs, as
long as they are established and implemented in a manner consistent with the CWA, its
implementing regulations, and EPA's 2003 Water Quality Trading Policy^ (USEPA 2003e) and
2007 Water Quality Trading Toolkit for NPDES Permit Writers2 (USEPA 2007d). An
assumption of this TMDL is that trades may occur between sources contributing pollutant
loadings to the same or different Bay segments, provided such trades do not cause or contribute
to an exceedance of WQS in either receiving segment or anywhere else in the Bay watershed.
EPA does not support any trading activity that would delay or weaken implementation of the
Bay TMDL, that is inconsistent with the assumptions and requirements of the TMDL. or that
would cause the combined point source and nonpoint source loadings covered by a trade to
exceed the applicable loading cap established by the TMDL.
See http://wvv\v.epa.gov/o\vo\v/\vatershed/trading/fmalpolicv2003.pdf.
: See http://www.eDa.gov'owow/watershed/tradina/WQTToolkit.html.
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Chesapeake Bay TMDL
In Section 10.1, EPA explains how Bay jurisdictions may accommodate new or increased
loadings of nitrogen, phosphorus, and sediment either through a specific TMDL allocation or by
offsetting those loadings with quantifiable and accountable reductions necessary to implement
applicable WQS in the Bay and its tidal tributaries. In Appendix S, EPA discusses a number of
definitions and common elements that EPA encourages and expects the jurisdictions to include
and implement in their offset programs. EPA believes the definitions and common elements in
Appendix S also constitute important components of trading programs in the Chesapeake Bay
watershed. EPA anticipates using these Appendix S definitions and elements in reviewing
jurisdictions' trading programs.
10.3 FUTURE MODIFICATIONS TO THE CHESAPEAKE BAY TMDL
EPA has established the Chesapeake Bay TMDL, including its component WLAs, LAs, and
margin of safety, based on the Bay and tidal tributaries' applicable WQS and the totality of the
information available to it concerning Bay Watershed water quality and hydrology, present and
anticipated pollutant sources and loadings, and jurisdiction-submitted implementation plans. In
establishing the TMDL and making determinations about reasonable assurance, EPA has also
relied on facts and assumptions regarding its own ability to ensure and successfully track TMDL
implementation through the two-year milestone process and the application, if necessary, of
appropriate federal actions. As a result, EPA believes this TMDL is an appropriate and effective
framework for the point source and nonpoint source-focused implementation activities that the
jurisdictions, EPA, and the other Bay watershed stakeholders must take to meet the Bay's
nitrogen, phosphorus, and sediment reduction goals.
EPA recognizes, however, that neither the world at large nor the Bay watershed is static. In a
dynamic environment like the Bay watershed, during the next 15 years change is inevitable. It
may be possible to accommodate some of those changes within the existing TMDL framework
without the need to revise it in whole, or in part. For example, EPA's permitting regulations at
!22.44(d)(l)(vii)(B) require that permit WQBELs be "consistent with the assumptions and
requirements of any available wasteload allocation for the discharge" contained in the TMDL.
As the EPA Environmental Appeals Board has recognized, "WLAs are not permit limits per se;
rather they still require translation into permit limits." In re City of Moscow, NPDES Appeal No.
00-10 (July 27, 2001). In providing such translation, the EAB said that "[wjhile the governing
regulations require consistency, they do not require that the permit limitations that will finally be
adopted in a final NPDES permit be identical to any of the WLAs that may be provided in a
TMDL." Id. Accordingly, depending on the facts of a particular situation, it may be possible for
the jurisdictions to write a permit limit that is consistent with (but not identical to) a given WLA
without revising that WLA (either increasing or decreasing a specific WLA), provided the permit
limit is consistent with the operative "assumptions " (e.g., about the applicable WQS, ambient
water quality conditions, the sum of the delivered point source loads, hydrology, implementation
strategies, the sufficiency of reasonable assurance) that informed the decision to establish that
particular WLA.
There might, however, be circumstances in which the permit authority is not comfortable with,
or the CWA would not allow, the degree to which a permit limit might deviate from a WLA in
the TMDL such that one or more WLAs and LAs in the Bay TMDL would need to be revised.
Or, fundamental assumptions like the nature and stringency of the applicable WQS or a
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Chesapeake Bay TMDL
jurisdiction's legal authority might change. In these cases, it might be appropriate for EPA to
revise the Bay TMDL (or portions of it). KPA would consider a request by the jurisdictions to
propose such a revision to the TMDL following appropriate notice and comment. Alternatively.
a jurisdiction could propose to revise a portion(s) of the Bay TMDL that applies within its
boundaries (including, but not limited to specific WLAs and LAs) and submit those revisions to
I-PA for approval. If EPA approved any such jurisdiction-submitted revisions, those revisions
would replace their respective parts in the EPA-established Bay TMDL framework. In approving
any such jurisdiction-submitted revisions (or in making its own revisions) EPA would ensure
that the revisions themselves met all the statutory and regulatory requirements for TMDL
approval and did not result in any component of the original TMDL not meeting applicable
WQS.
Based on possible updates to the model and on jurisdictions' WIPs, EPA will consider revising
the Chesapeake Bay TMDL, if appropriate, in 2012 and 2017. EPA will also consider revising
the TMDL based on other new or additional information provided by the jurisdictions. All
revision requests from jurisdictions should be coordinated with EPA to fit within EPA's planned
revision time frame.
10.4 FEDERAL FACILITIES AND LANDS
Federal lands account for approximately 5.3 percent of the Chesapeake Bay watershed. The
federal sector is like other sectors in that EPA expects federal land owners to be responsible for
achieving LAs and WLAs through actions, programs, and policies that will reduce the release of
nitrogen, phosphorous, and sediment (CWA section 313, 33 U.S.C. 1323).
EPA expects federal agencies with property in the watershed to provide leadership and work
with the seven Bay watershed jurisdictions in implementing their Phase I WIPs. Federal agencies
have provided information on the spatial boundaries and land use types for facilities in the
watershed. EPA used that information to model current pollutant loads from federal facilities and
has provided the estimated loads to the jurisdictions. The Federal Strategy also requires federal
agencies with property in the Bay watershed to work with the jurisdictions in developing their
WIPs by identifying pollutant reductions from point and nonpoint sources associated with federal
lands and committing to actions, programs, policies, and resources necessary to reduce nitrogen.
phosphorus, and sediment by specific dates.
In their final Phase I WIPs, jurisdictions have established load reduction goals for sectors
contributing nitrogen, phosphorus, and sediment loads to the Chesapeake Bay. The TMDL
allocations are based almost wholly upon these load reductions; federal lands and installations
are expected to contribute to these load reductions. In the Phase II WIPs, the jurisdictions are
expected to further distribute LA and WLA allocations among local level target areas such as
counties. These more local targets also could include federal facilities. EPA also expects that
federal agencies will cooperate with Bay jurisdictions and provide them with information on
federal agency actions, programs, policies, and resources necessary to achieve federal facility-
specific load reduction targets in jurisdictions' Phase II WIPs.
Like the Bay jurisdictions, federal agencies are expected to create 2-year milestones detailing
specific implementation actions to achieve federal lands' and facilities' share of load reductions.
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Chesapeake Bay TMDL
These federal milestones also should support the implementation of jurisdictions' WIPs and two-
year milestones through commitments to comply with permit conditions and provide
coordination, funding, and technical assistance, as appropriate. The milestones will be the basis
for tracking progress and providing transparency on federal sector performance related to agency
TMDL responsibilities in the watershed.
Federal facility-specific target loads are expected to be included in the jurisdictions' Phase II
WIPs in 2011 via one of two approaches: (a) jurisdictions could establish explicit load reduction
expectations for federal facilities as part of the Phase II WIP process; or (b) on the basis of broad
load reduction goals established by the jurisdiction, individual federal facilities/installations
could develop Federal Facility Implementation Plans (FFIPs), which would explain to the
jurisdiction how the facility would achieve needed load reductions in nitrogen, phosphorus, and
sediment. The FFIPs would be expected to address, at a minimum, the following in targeting and
achieving load reductions:
• Assess properties to determine the feasibility of installing urban retrofit practices and
implementing nonstructural control measures that reduce volume and improve quality of
stormwater runoff.
• Align cost-effective, urban stormwater retrofits and erosion repairs with the Bay TMDL
allocations and jurisdictions' 2-year milestones.
• Assess and implement appropriate nonstructural practices to control stormwater discharges
from developed areas and to reduce, prevent, or control erosion from unpaved roads, trails,
and ditches.
• Consider the full spectrum of nitrogen, phosphorus, and sediment sources at a facility or
installation to assess the ideal approach to achieve the needed nitrogen, phosphorus, and
sediment reduction.
In addition, section 501 of Executive Order 13508 and the subsequent Executive Order Federal
Strategy (FLCCB 2010) direct each federal agency with land, facilities or installation
management responsibilities affecting 10 or more acres in the Bay watershed to implement
section 502 guidance on federal land management. Pursuant to section 502 of the Executive
Order, EPA issued on May 12, 2010, the Guidance for Federal Land Management in the
Chesapeake Bay Watershed (EPA May 12, 2010), EPA 841-R-10-002 (section 502 guidance).
EPA's objective in developing the section 502 guidance was to provide information and data on
appropriate, proven, and cost-effective tools and practices for implementation on federal lands
and at federal facilities.
The section 502 guidance includes chapters addressing agriculture, urban and suburban areas
(including turf), forestry, riparian area management, decentralized wastewater treatment systems,
and hydromodification. Each chapter contains one or more implementation measures that
provide the framework for the chapter. They are intended to convey the actions that will help
ensure that the broad goals of the Chesapeake Bay Executive Order are achieved. Each chapter
also includes information on practices that can be used to achieve the goals; information on the
effectiveness and costs of the practices; where relevant, cost savings or other economic/societal
benefits (in addition to the pollutant reduction benefits) that derive from the implementation
goals or practices; and copious references to other documents that provide additional
information. Federal agencies are expected to incorporate the section 502 guidance as part of
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Chesapeake Bay TMDL
their overall strategy to meet the loading reductions that the jurisdictions in their Phase II WIPs
assign to them.
In addition, the Executive Order Federal Strategy calls for federal agencies to adopt an agency-
specific policy to ensure implementation of the stormwater requirements in section 438 of the
Hnergy Independence and Security Act (EISA) for new development and redevelopment
activities consistent with guidance developed by EPA. Section 438 of EISA requires federal
agencies to maintain or restore the predevelopment hydrology (the runoff volume, rate,
temperature, and duration of flow that typically existed on the site before human-induced land
disturbance occurred) of any project with a footprint that exceeds 5,000 square feet. The agency-
specific policy should include mechanisms for producing an annual internal agency action plan
and progress report. Implementation of the agency-specific policy is to begin in 2011. The results
of each federal agency's actions to comply with section 438 of EISA will be published as part of
the annual progress report issued under the direction of the Executive Order discussed above.
10.5 FACTORING IN EFFECTS FROM CONTINUED CLIMATE CHANGE
EPA accounted for the potential effects of future climate change in the current Bay TMDL
allocations based on a preliminary assessment of climate change impacts on the Chesapeake Bay
(see Section 5.11 and Appendix E). There are well-known limitations in the current suite of Bay
models to fully simulate the effects of climate change as cited in Section 5.11.
EPA and its partners are committed to conducting a more complete analysis of climate change
effects on nitrogen, phosphorus, and sediment loads and allocations in time for the mid-course
assessment of Chesapeake Bay TMDL progress in 2017 as called for in Section 203 of the
Chesapeake Executive Order 13508 (May 12, 2009), accessible at
http://executiveorder.chesapeakebay.net/EO/ file. axd?file=2009%2rK%2fChesapeake+Executive
+Order.pdf. To do that will require building the capacity to quantify the impacts of climate
change at the scale of the Bay TMDL—92 Bay segments and their surrounding watersheds at the
scale of the Phase II Watershed Implementation Plans' target loads—and incorporate that
information into the full suite of Bay models and other decision support tools.
EPA has committed to take an adaptive management approach to the Bay TMDL and incorporate
new scientific understanding of the effects of climate change into the Bay TMDL, in this case
during the mid-course assessment.
10.6 SEDIMENT BEHIND THE SUSQUEHANNA RIVER DAMS
The dams along the lower Susquehanna River are a significant factor influencing nitrogen,
phosphorus, and sediment loads to the Bay because they retain large quantities of sediment and
phosphorus, and some nitrogen, in their reservoirs (Appendix T). The three major dams along the
lower Susquehanna River are the Safe Harbor Dam, Holtwood Dam, and Conowingo Dam. In
developing the TMDL, EPA considered the impact ot these dams on the pollutant loads to the
Bay and how those loads will change when the dams no longer function to trap nitrogen,
phosphorus, and sediment.
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Chesapeake Bay TMDL
The Bay TMDL incorporates the current sediment-trapping capacity of the Conowingo Dam at
55 percent, with nitrogen and phosphorus trapping capacity at 2 percent and 40 percent,
respectively. That allows the sediment, nitrogen, and phosphorus allocations to the jurisdictions
to reflect the actual input to the Bay. If future monitoring shows a change in trapping capacity in
the Conowingo Dam, the 2-year milestone delivered load reductions could be adjusted
accordingly. The adjusted loads may be compared to the 2-year milestone commitments to
ensure that each jurisdiction is meeting its obligations. For example, if there were a reduction in
the sediment-trapping capacity in the reservoir, an upland jurisdiction might need to increase its
sediment-reduction efforts to meet the allocations it has been assigned in the Bay TMDL. The
jurisdictions' sediment allocation would not necessarily change, but the jurisdictions might need
to increase the level of effort in reducing sediment to account for the loss of trapping capacity in
the reservoir. Changes in the sediment-trapping capacity are not expected to alter the amount of
sediment that the Bay is able to assimilate and, therefore, are not expected to change the
allocations in this Bay TMDL.
For the purposes of the Chesapeake Bay TMDL, EPA and the partners assumed the current
trapping efficiencies will continue. If future monitoring shows that trapping efficiencies are
reduced, Pennsylvania, New York, and Maryland's respective 2-year milestone delivered loads
could be adjusted accordingly. Therefore it is imperative that those jurisdictions work together to
develop an implementation strategy for addressing the sediment, nitrogen, and phosphorus
behind the Conowingo Dam through their respective WIPs, so that they are prepared if the
trapping efficiencies decrease.
10.7 FILTER FEEDERS
Filter feeders play an important role in the uptake of nitrogen and phosphorus from the
Chesapeake Bay and have the potential significantly improve water quality if present in large
numbers (Appendix U). The organisms of interest for their ability to improve water quality are
the native Eastern oyster, Crassostrea virginica, and menhaden fish, Brevoortia tyrannus. Each
market-sized oyster contains about 0.5 gram of nitrogen and O.I 6 gram of phosphorus.
Menhaden fish are another filter feeding organism in the Chesapeake Bay. The Chesapeake Bay
TMDL incorporates the effects of filter feeders.
EPA is basing the TMDL on the current assimilative capacity of filter feeders at existing
populations built into the calibration of the oyster filter feeding submodel of the Chesapeake Bay
Water Quality and Sediment Transport Model. Potential future population changes are not
accounted for in the Bay TMDL. If future monitoring data indicate an increase in the filter feeder
population, the appropriate jurisdiction's 2-year milestone delivered load reductions can be
adjusted accordingly. Similarly if reductions in future filter feeder populations are observed that
result in reduced nutrient assimilation, the 2-year milestone delivered load reductions can be
adjusted to account for the change. The adjusted loads will be compared to the 2-year milestone
commitments to ensure that each jurisdiction is meeting its obligations.
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Chesapeake Bay TMDL
SECTION 11. PUBLIC PARTICIPATION
EPA and the Bay jurisdictions have benefitted from a comprehensive effort to exchange
information with key stakeholders and the broader public on the Chesapeake Bay TMDL.
The Bay TMDL has been the subject of public discussion and close interaction between EPA and
the seven watershed jurisdictions since 2005. Activities to further public involvement in the Bay
TMDL will continue in 2011 and beyond as the TMDL is implemented.
The concentrated outreach period of 2009 and 2010 leading up to the establishment of the
TMDL is of particular focus in this section. That 2-year effort featured hundreds of meetings
with interested groups; two extensive rounds of public meetings, stakeholder sessions, and media
interviews throughout the watershed; a dedicated EPA website; a series of monthly interactive
webinars accessed online by more than 2,500 people; three notices published in the Federal
Register; and a close working relationship with Chesapeake Bay Program committees
representing citizens, local governments, and the scientific community.
The states and the District of Columbia have also involved stakeholders and the broader public in
the development of their Watershed Implementation Plans, which informed the Bay TMDL.
11.1 Stakeholder and Local Government Outreach and Involvement
EPA has made a concerted effort over the past years to involve a variety of stakeholders,
including local governments, in the development of the Chesapeake Bay TMDL. This subsection
describes some of the more significant aspects of that effort.
11.1.1 Open Collaboration with Stakeholders
EPA has taken extra efforts to reach out to groups and sectors that will be particularly affected
by the Bay TMDL. Since 2008, EPA principals involved in developing the Bay TMDL have
attended nearly 400 meetings with a wide range of groups throughout the watershed to give and
receive information about the TMDL. A list of those meetings is provided in Appendix C.
During the course of months-long outreach campaigns in the fall of 2009 and 2010, EPA teams
conducted nearly 100 separate meetings and briefings with key stakeholder groups to share
sector-specific information and address sector-focused questions. Those groups included farmers
and producers, homebuilders and developers, municipal wastewater authorities, local elected
officials, conservation groups, and environmental advocacy organizations. The outreach
generated key insights and perspectives.
11.1.2 Outreach to Local Governments and Elected Officials
EPA and the watershed jurisdictions have made a special effort to involve local governments in
the Bay TMDL process to better understand how the TMDL can best be tailored to local scales
for implementation. EPA and the jurisdictions will have more targeted discussions with local
officials starting in 2011 as the Phase II Watershed Implementation Plans from the states and the
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Chesapeake Bay TMDL
District offer a finer scale commitment to meeting the pollution reduction allocations. EPA has
and is willing to use the scientific ability in the TMDL to identify pollution sources and impacts
on a relatively local level.
11.1.3 Local Pilots
EPA provided $300,000 in technical assistance for a series of pilot projects to help the
jurisdictions engage local partners as part of their Watershed Implementation plan Process. Local
governments, conservation districts, watershed groups and others were eligible for a share of the
assistance. The projects are demonstrating how local needs, priorities, and existing restoration
efforts can be incorporated in the implementation plans. EPA awarded funds to the following
communities and watersheds:
District of Columbia
Maryland: Anne Arundel and Caroline counties
New York: Chemung River watershed
Pennsylvania: Conewago Creek watershed
Virginia: Prince William County and Rivanna River basin
West Virginia: Berkeley, Jefferson, and Morgan counties
Information on the pilot projects is at
http://www.epa.gov/reg3wapd/pdf/ndf chesbav/WIPPilotProjectSummarv 82010.pdf.
11.2 Public Outreach
EPA's extensive outreach efforts included public meetings, webinars, and a dedicated website
that facilitated a continuing dialogue between EPA, the seven watershed jurisdictions, and key
stakeholders on the Chesapeake Bay TMDL for nitrogen, phosphorus, and sediment.
11.2.1 Public Meetings
Two rounds of public meetings in each of the watershed jurisdictions were a centerpiece of
EPA's outreach efforts.
November-December 2009 Public Meetings
EPA and its jurisdiction partners sponsored 16 public meetings in the fall of 2009 to share
information on the forthcoming Bay TMDL. A number of the public meetings were broadcast to
a live, online audience via webinar. More than 2,000 people participated in the meetings,
including 1,815 in person and 263 online via webinar at six of the locations. There was also a
kickoff public meeting in Richmond, Virginia, in October 2009 that drew a combined live and
online audience of more than 400 people.
The 2009 public meetings were held in
Martinsburg, West Virginia, November 4*
Moorefield, West Virginia, November 5
Washington, D.C., November 16*
Ashley, Pennsylvania, November 17
Williamsport, Pennsylvania, November 18
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State College, Pennsylvania, November 19
Lancaster, Pennsylvania, November 23*
Binghamton, New York, December 1*
Baltimore, Maryland, December 8*
Laurel, Delaware, December 10*
Wye Mills, Maryland, December 11
Falls Church, Virginia, December 14
Chesapeake, Virginia, December 15
Williamsburg, Virginia, December 15
Penn Laird, Virginia, December 16
Fredericksburg, Virginia, December 17
* Meeting also was broadcast online via webinar. The largest live audiences were in Penn Laird,
Virginia (205), and Lancaster, Pennsylvania (196).
September-November 2010 Public Meetings
The draft Chesapeake Bay TMDL was issued on September 24, 2010, commencing a 45-day
public comment period. During that comment period, a total of 18 public meetings were held in
all seven watershed jurisdictions. As in 2009, one of the meetings in each jurisdiction was
broadcast online via webinar to a broader audience. The times, specific locations, directions, and
parking information were posted on the Bay TMDL website:
http://www.epa.uov/chesapeakebavtmdl.
HPA and the respective jurisdictions each made presentations during the public meetings. Those
presentations were posted on the Bay TMDL website as they happened. They can be found on
the site as part of a summary of the 2010 public meetings.
Nearly 2,800 people participated in the meetings, including 2,311 in person (estimated based on
sign-in sheets and headcounts) and 477 online via webinar.
The meetings and attendance figures were as follows:
Washington, D.C., September 29* (29 in person, 74 online)
Harrisonburg, Virginia, October 4 (330)
Annandale, Virginia, October 5 (135)
Richmond, Virginia, October 6 (250)
Webinar, October 7 (9 in person, 160 online)
Hampton, Virginia, October 7 (165)
Georgetown, Delaware, October 11* (90 in person. 16 online)
Easton, Maryland, October 12(111)
Annapolis, Maryland, October 13 (200)
Hagerstown, Maryland, October 14* (60 in person, 65 online)
Lancaster, Pennsylvania, October 18 (200)
State College, Pennsylvania, October 19(101)
Williamsport, Pennsylvania, October 20* (80 in person, 101 online)
Ashley, Pennsylvania, October 21 (40)
FJmira, New York, October 26 (120)
Binghamton, New York, October 27* (120 in person, 42 online)
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Martinsburg, West Virginia, November 3 (100)
Romney, West Virginia, November 4* (171 in person. 19 online)
* Meeting also broadcast online via webinar Webinar registration links were available on the
Bay TMDL website listed above.
11.2.2 Webinars to Expand Audiences
EPA Region 3 was one of the first regional offices to acquire capacity to host large webinars.
The system was obtained specifically to broadcast a representative number of the 2009 fall
public meetings to online audiences, thus expanding the ability for the public to hear and
participate in the meetings. Webinars were broadcast about monthly and were incorporated in a
number of the fall 2010 public meetings—one in each jurisdiction.
Monthly Webinars
EPA sponsored monthly webinars in 2010 to keep the public up to date on Bay TMDL
developments. The seven webinars drew a collective audience of 2,587 participants. The
regularly scheduled webinars represent one of EPA's Open Government flagship initiatives for
public outreach. A substantial portion of each webinar was reserved for informal questions and
answers.
The monthly webinars were advertised widely using stakeholder and jurisdiction lists of
hundreds of people and organizations that have expressed an interest in the Bay TMDL. The
registration links for the webinars were published prominently on the Bay TMDL website.
The monthly webinars were held on
February 25, 2010 TMDL Update 1 529 participants
March 25, 2010 TMDL Update 2 379 participants
May 17, 2010 TMDL Update 3 294 participants
June 7, 2010 TMDL Update 4 288 participants
July 8, 2010 TMDL Update 5 383 participants
August 9, 2010 TMDL Update 6 385 participants
September 28, 2010 TMDL Update 7 329 participants
Webinars Tailored to Specific Stakeholder Communities
In addition to the monthly webinars, EPA sponsored two webinars to review detailed modeling
and other technical information with representatives of the agriculture and development
communities.
The webinars were held on
March 22, 2010 Webinar for the Agriculture Community 218 participants
May 6, 2010 Webinar for the Development Community 84 participants
11-4 December 29, 2010
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11.2.3 Chesapeake Bay TMDL Website
EPA established a website for the Chesapeake Bay TMDL in August 2009. The address is
http:/Av w\v.epa.gov/chesapeakebavtmdl.
The site continues to include the latest news and information on the Bay TMDL, along with fact
sheets, questions and answers, presentations, and other features. The site has consistently been
one of the most popular in EPA Region 3 according to access numbers.
In addition, the Chesapeake Bay Program partnership's website (wvvvs.chesapeakebay.net) has
contained detailed information involving Bay TMDL proceedings, including scientific data,
PowerPoint presentations, and other items used in the process.
11.2.4 Public Notices
Federal Register Notices
EPA has issued two notices in the Federal Register regarding the Chesapeake Bay TMDL to
ensure that the public has full advance notification of major events. The notices include a
September 17, 2009, announcement (USEPA 2009a) of the public meetings and a September 22.
2010 announcement (USEPA 20lOc) of the public review and comment period. EPA issued a
third notice to announce establishment of the final Chesapeake Bay TMDL.
Newspaper Notices
EPA has issued notices in regional and local newspapers regarding the Chesapeake Bay TMDL
to ensure that the public throughout the watershed has full advance notification of major events.
11.3 Responses to Public Comments
The Draft Chesapeake Bay TMDL was available for public comment from September 24, 2010,
to November 8, 2010. Comments were accepted electronically via Docket ID No. EPA-R03-
OW-2010-0736 at wuw.reuulations.gov. by mail, and by hand delivery. A link to review and
comment on the Bay TMDL was provided through the Bay TMDL website.
EPA received more than 14,000 comments on the Bay TMDL, including more than 700 detailed
comment letters. More than 90 percent of the comments, including many similar submissions,
were in favor of the TMDL. Comments came from many different sources, including individual
citizens, industry, local government, environmental organizations, and academia.
A team of EPA specialists reviewed and responded to all written comments submitted during the
public comment period and the comments were considered, as appropriate, in the establishment
of the final Bay TMDL. Responses to the comments are included in Appendix W in the final Bay
TMDL document.
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11.4 Interaction with States, D.C. on Watershed Implementation Plans
EPA provided considerable assistance to the six watershed states and the District of Columbia in
the development of their draft and final WIPs. In addition to financial and technical assistance,
EPA held numerous meetings and conference calls with each of the jurisdictions to provide input
and guidance and to reiterate expectations for the WIPs. A listing of those conference calls and
meetings are included in Appendix C in this document.
11-6 December 29, 2010
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Martucci, S.K., J.L. Krstolic, J.P. Raffensperger, and K.J. Hopkins. 2006. Development of Land
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Chesapeake Bay TMDL
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Chesapeake Bay TMDL
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SECTION 13. GLOSSARY
Airshed. A geographic area delineating the relative location of air emission sources contributing
to the atmospheric deposition to a down-wind watershed.
Allocations. Best estimates of current and future pollutant loads (both nonpoint and point
sources) entering a water body. Pollutant load estimates can range from reasonably accurate
measurements to gross estimates and the techniques used for predicting specific loads.
Ammonia. An inorganic nitrogen compound. In water, ammonia levels in excess of the
recommended limits may harm aquatic life.
Assimilative Capacity. The capacity of a natural body of water to receive wastewaters or toxic
materials without deleterious effects and without damage to aquatic life or humans who consume
the water.
Bay Segment. Subunits of the Chesapeake Bay estuary that were derived on the basis of specific
selection criteria related to factors such as jurisdictional boundaries and other water quality.
physical, geographic, and habitat related characteristics. The Chesapeake Bay and its tidal
tributaries and embayments are divided into 92 segments.
Best Management Practices. Methods that have been determined to be the most effective.
practical means of preventing or reducing pollution from non-point sources.
Bloom. A proliferation of algae or higher aquatic plants (or both) in a body of water; often
related to pollution, especially when pollutants accelerate growth. Blooms are often the result of
excessive levels of nutrients—generally nitrogen and phosphorus—in water.
Boundary' Conditions. The definition or statement of conditions or phenomena at the
boundaries of a model; water levels, flows, and concentrations that are specified at the
boundaries of the area being modeled.
Chlorophyll a. A photosynthetic pigment that is found in green plants. The concentration of
chlorophyll a is used as an indicator of water quality.
Critical Condition. Critical conditions are represented by the combination of loading,
waterbody conditions, and other environmental conditions that result in impairment and violation
of water quality standards. Critical conditions for an individual TMDL typically depend on
applicable water quality standards, characteristics of the observed impairments', source type and
behavior, pollutant, and waterbody type.
Critical Period. A period during which hydrologic, temperature, environmental, flow, and other
such environmental conditions result in a waterbody being most sensitive to an identified
impairment (e.g., summer low flow, winter high flow).
Delist. To remove an impaired waterbody from the Section 303(d) Impaired Waters List.
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Delivered Load. The amount of a pollutant delivered to the tidal waters of the Chesapeake Bay
or its tidal tributaries from an upstream point of discharge/runoff after accounting for permanent
reductions in pollutant loads due to natural in-stream processes in nontidal rivers.
Edge-of-Stream Load. The amount of a pollutant reaching a simulated stream segment from a
point in that stream's watershed.
Effluent. Wastewater, either treated or untreated, that flows out of a treatment plant, sewer, or
industrial outfall. Generally refers to wastes or waters containing pollutants discharged into
surface waters.
Eutrophication. The slow aging process during which a lake, estuary, or bay evolves into a bog
or marsh and eventually disappears. During the later stages of eutrophication the water body is
choked by abundant plant life due to higher levels of nutritive compounds such as nitrogen and
phosphorus. Human activities can accelerate the process.
Existing Flow. The average flow volume discharged from a facility based on monitored data.
Facility Design Flow. The maximum flow volume for which a facility is designed and permitted
to operate at.
Failing Septic System. Septic systems in which the drain field has failed such that effluent that
is supposed to percolate into the soil, rises to the surface and pools on the surface where it can
run into streams or rivers.
Impaired Waters. Waters with chronic or recurring monitored violations of the applicable
numeric or narrative water quality standards.
Load Allocation. The portion of the TMDL allocated to existing or future nonpoint sources and
natural background.
Loading Capacity. The greatest pollutant loading a waterbody can receive without exceeding
water quality standards.
Mainstem Bay. The Chesapeake Bay, from Havre de Grace, Maryland to the Virginia Capes,
without the tidal tributaries and embayments included.
Margin of Safety. An accounting of uncertainty about the relationship between pollutant loads
and receiving water quality. The margin of safety can be provided implicitly through analytical
assumptions or explicitly by reserving a portion of loading capacity.
Mesohaline. Salinity regime with >5-18 parts per thousand salinity.
Mixing Zone. A limited area or volume of a receiving water body where the initial dilution
occurs and a permitted or authorized discharge occurs. Mixing zones are supposed to dilute or
reduce pollutant concentrations below applicable water quality standards such that the applicable
criteria in the standards are met at the edge of the mixing zone.
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Model. A system of mathematical expressions that describe and represent the physical world or
some aspect therein. In the Bay TMDL, models are used to describe both hydrologic and water
quality processes as well as estimate the load of a specific pollutant to a water body and make
predictions about how the load would change as remediation methods (e.g. scenarios) are
implemented.
National Pollutant Discharge Elimination System (NPDES) permit program is authorized by
the Clean Water Act and works to control water pollution by regulating point sources that
discharge pollutants into waters of the United States. Industrial, municipal, and other facilities
must obtain permits for any discharge into waters of the United States. In most cases, the NPDES
permit program is administered by authorized states or EPA.
Nonpoint Source. Any source of water pollution that does not meet the legal definition of point
source. Nonpoint source pollution generally results from land runoff, precipitation, atmospheric
deposition, drainage, seepage, or hydrologic modification.
Nonsignificant Discharge Facility. A municipal or industrial wastewater discharge facility that
is not defined as a significant discharge facility by the jurisdiction in which it is permitted. In
general but not always, nonsignificant municipal facilities have design flows less than 0.4
million gallons per day (Virginia and Maryland thresholds are slightly different). Nonsignificant
industrial facilities discharge less than 3,800 pounds per year total phosphorus and less than
27,000 pounds per year total nitrogen.
Oligohaline. Salinity regime with >0.5-5 parts per thousand salinity.
Point Source. Any discernible, confined, and discrete conveyance, including but not limited to
any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock,
concentrated animal feeding operation, vessel or other floating craft from which pollutants are or
may be discharged.
Pollutant Source Sector. Category of related sources of nutrient and sediment loads identified
for purposes of quantifying load allocations. Examples include agriculture, wastewater, forest,
urban runoff.
Polyhaline. Salinity regime with 0-0.5 parts per thousand salinity.
Pycnocline. The depth in the water column where there is an abrupt change in density,
temperature, and salinity. A pycnocline often forms in the Chesapeake Bay and its tidal
tributaries when the lighter, warmer, and fresher water coming downstream from the spring rains
overlays the denser, colder, and saltier water of the salt wedge bringing water upstream from the
ocean.
Residence Time. Length of time that a pollutant remains with a section of a stream or river.
Residence time is determined by streamflow and volume of the body in question.
Riparian. Referring to the areas adjacent to rivers and streams with a differing density, diversity,
and productivity of plant and animal species relative to nearby uplands.
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Runoff. That part of precipitation, snow melt, or irrigation water that runs off the land into
streams or other surface-water. It can carry pollutants from the air and land into receiving waters.
Section 303(d). A section of the Clean Water Act that requires periodic identification of waters
that do not or are not expected to meet applicable water quality standards and the establishment
of TMDLs for such waters.
Sediment. Soil, sand, and minerals washed from the land into water, usually after rain or snow
melt.
Segment Watershed. Watershed area draining into one of the 92 Chesapeake Bay segments.
Significant Discharge Facility. A municipal or industrial wastewater facility defined as such by
the jurisdiction in which it is permitted. Significant facilities are distinguished from
nonsignificant facilities on the basis of flow for municipals and loads for industrials. In general
but not always, significant municipal facilities have flows larger than 0.4 million gallons per day,
and significant industrial facilities discharge loads larger than 3,800 pounds per year of total
phosphorus and 27,000 pounds per year of total nitrogen!
Simulation Period. A period used to run the model scenario simulation, selected to ensure that
the simulated rainfall, meteorological, and environmental time series used to drive the watershed
simulation such that it accurately simulates the critical conditions.
Suspended Solids. Small particles of solid pollutants that float on the surface of, or are
suspended in, sewage or other liquids. They resist removal by conventional means.
Tidal Fresh. Salinity regime with 0-0.5 parts per thousand salinity.
Total Maximum Daily Load. Specifies the maximum amount of a pollutant that a waterbody
can receive and still meet applicable water quality standards. It is the sum of the allocations for
point sources (called wasteloads) and allocations for nonpoint sources (called loads) and natural
background with a margin of safety (CWA section 303(d)(l)(c)). The TMDL can be described
by the following equation:
TMDL = LC = IWLA + ILA + MOS
Turbidity. A measure of the cloudy condition in water due to suspended solids or organic
matter.
Wasteload Allocation. The portion of the TMDL allocated to existing, potential or future point
sources.
Water Clarity Acre. An acre of shallow-water bay grass designated-use bottom habitat, located
anywhere between the 2-meter depth contour and the adjacent shoreline inclusively, which has
been observed to achieve the applicable salinity-regime-specific water clarity criteria.
Watershed. An area of land from which all water drains to a common point.
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SECTION 14. ABBREVIATIONS
ug/L microgram per liter
ADM annual/daily maximum ratio
AEU animal equivalent units
AFO animal feeding operation
ASMFC Atlantic States Marine Fisheries Commission
BART best available retrofit technology
BayTAS Chesapeake Bay TMDL Tracking and Accountability System
BMP best management practice
BOD biological oxygen demand
CAA Clean Air Act
CAC Citizen's Advisory Committee
CAFO concentrated animal feeding operation
CAMR Clean Air Mercury Rule
CBLCD Chesapeake Bay land cover data
CBP Chesapeake Bay Program
CEC Chesapeake Executive Council
CFD cumulative frequency distribution
CFR Code of Federal Regulations
CIMS Chesapeake Information Management System
CMAQ Community Multi-scale Air Quality model
COE U.S. Army Corps of Engineers
COMAR Code of Maryland
CONMON continuous monitoring
CSO combined sewer overflow
CSS combined sewer system
CWA Clean Water Act
DAITS Data and Information Tracking System
DC District of Columbia
DC WASA District of Columbia Water and Sewer Authority
DE Delaware
DE DNREC Delaware Department of Natural Resources and Environmental Control
DMR discharge monitoring report
DO dissolved oxygen
DUQAT Data Upload and Quality Assurance Tool
E3 everything by everyone everywhere
EGU electric generating unit
EISA Energy Independence and Security Act
ELU effluent limit guidelines
EO Executive Order
EPA U.S. Environmental Protection Agency
FFIP federal facility implementation plan
FR Federal Register
GIS geographic information system
ICIS Integrated Compliance Information System
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Kd light attenuation coefficient
LA load allocation
Ibs pounds
LC loading capacity
LGAC Local Governments Advisory Committee
Ln natural log
LOESS locally weighted scatter plot smoother
LTCP Long-Term Control Plan
m meter
MAWP Mid-Atlantic Water Program
MD Maryland
MDE Maryland Department of the Environment
mgd million gallons per day
mg/L milligrams per liter
MOS margin of safety
MOU memorandum of understanding
MRAT Monitoring Realignment Action Team
MS4 Municipal Separate Storm Sewer System
NADP National Atmospheric Deposition Program
NAS National Agricultural Statistics
NEIEN National Environmental Information Exchange Network
NHs ammonia
NHt+ ammonium
NMFS National Marine Fisheries Service
NMP nutrient management plan
NO2 nitrite
NOa nitrate
NOI notice of intent
NOx nitrogen oxides
NOAA National Oceanic and Atmospheric Administration
NPDES National Pollutant Discharge Elimination System
NRCS Natural Resources Conservation Service
NY New York
OSWTS on-site wastewater treatment system
PA Pennsylvania
PA DEP Pennsylvania Department of Environmental Protection
PAR photosynthetically active radiation
PCS Permit Compliance System
PLW percent light through water
POTW publicly owned treatment works
PSC Principals' Staff Committee
ppt parts per thousand (salinity)
QA quality assurance
QA/QC quality assurance/quality control
RDA Residual Designation Authority
RESAC University of Maryland's Regional Earth Science Applications Center
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SAV submerged aquatic vegetation
SCR selective catalytic reduction
SIP state implementation plan
SNCR selective non-catalytic reduction
SPARROW Spatially Referenced Regressions on Watershed Attributes
SSO sanitary sewer overflow
STAC Scientific and Technical Advisory Committee
TMDL total maximum daily load
TN total nitrogen
TP total phosphorus
TSS total suspended solids
USC Upper Susquehanna Coalition
U.S.C. United States Code
USDA U.S. Department of Agriculture
USGS U.S. Geological Survey
VA Virginia
VA DEQ Virginia Department of Environmental Quality
VA DCR Virginia Department of Conservation and Recreation
WIP watershed implementation plan
WLA wasteload allocation
WQBELs water quality-based effluent limits
WQGIT Water Quality Group Implementation Team
WQS water quality standards
WV West Virginia
WV DEP West Virginia Department of Environmental Protection
WWTP waste water treatment plant
yr year
z depth
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