United States
Environmental Protection
Agency
Total Maximum Daily Loads
THSDLs
and New York
TMDL at a Glance
Long Island Sound Nitrogen TMDL
(approved April 2001)
www.longislandsoundstudY.net/pubs/reports/Tmcll.pclf
Lessons in Innovation and Collaboration
Is it possible to make significant reductions in pollution while saving tax payers a large
amount of money? Stakeholders in the Long Island Sound are demonstrating that it
is possible, using innovative approaches and multi-state collaboration. Once referred
to as the American Mediterranean for its unspoiled beauty, the nature of the Long
Island Sound has dramatically changed to an urban sea due to decades of growth and
development. Today the Sound's watershed is home to almost 9 million people with an
area that includes most of Connecticut and portions of New York, Rhode Island, New
Hampshire, Massachusetts, and Vermont. Pollutant sources associated with increased
urbanization, including sewage treatment plants and stormwater runoff, have
discharged excessive levels of nitrogen to the Sound leading to increased algal
blooms and decreased dissolved oxygen (DO) levels. As a result of eutrophication
and hypoxia, large areas in the western portion of the Sound can not support
aquatic life, recreation, and other important uses.
Factors causing impairment
Aesthetics, fishing, and water contact recreation
designated uses impaired due to reduced dissolved
oxygen levels and excessive algal blooms
Sources contributing to impairment
Sewage treatment plants, combined sewer overflows,
agricultural runoff, urban runoff, and atmospheric
deposition
Restoration options
Attain a 58.5 percent reduction in nitrogen discharges
to Long Island Sound from Connecticut and New York.
Upgrade sewage treatments plants with nitrogen
removal technologies, implement a nitrogen credit
trading program, issue bubble permits to sewage
treatment plants, reduce atmospheric deposition by
controlling nitrous oxide emissions from vehicles,
control polluted runoff through stormwater best
management practices and growth management
a Stakeholder involvement
Long Island Sound Study partners, including state
and federal agencies, private organizations, and
educational institutions; Connecticut Department
of Environmental Protection; New York State
Department of Environmental Conservation;
municipalities along the Sound's shore throughout
New York; municipalities in Connecticut; New England
Interstate Water Pollution Control Commission;
U.S. Environmental Protection Agency
Status of waternody
Nitrogen loading to Long Island Sound reduced by
25 percent from the adjusted 1990 baseline load.
Benefits to stakeholders
Reduced nitrogen loads, cost savings, funding,
partnerships
To address the water quality problems in the Long Island Sound, EPA created the
Long Island Sound Study (LISS) in partnership with the Connecticut Department
of Environmental Protection (CTDEP) and the New York State Department
of Environmental Conservation (NYSDEC). The LISS focuses on research,
monitoring, and modeling of the Sound to effectively address nitrogen loads,
improve DO levels, and meet water quality standards. Work conducted through
the LISS helped to support the development of the nitrogen TMDL for the Long
Island Sound, a joint effort by the states of Connecticut and New York. Innovative
implementation strategies, including a nitrogen credit trading program for sewage
treatment plants (STPs) in Connecticut and bubble permits for STPs in New York,
have not only led to significant nitrogen reductions in Long Island Sound, but also
significant cost savings.
How are TMDLs at work in Long Island Sound?
Years of research, monitoring, and modeling helped the LISS to identify nitrogen
sources in the Long Island Sound and levels of nitrogen control necessary to
improve DO levels and meet water quality standards. The analysis conducted by
the LISS led to the adoption of a 58.5 percent nitrogen reduction target to reduce
the extent and duration of hypoxic conditions in the Long Island Sound. Through
the TMDL development process, CTDEP and NYSDEC were able to incorporate
the 58.5 percent nitrogen reduction target into a regulatory and legal framework.
The Clean Water Act (CWA) requires implementation of pollutant load reductions
through point source permits issued under the National Pollutant Discharge
Elimination System (NPDES) Program. As a result, CTDEP and NYSDEC point
source permit writers must develop permit requirements to implement the
What is a total maximum daily load (TMDL)?
It is a study or analysis that calculates the maximum amount of a pollutant that a waterbody can receive and still meet
water quality standards. The TMDL establishes a pollutant budget and then allocates portions of the overall budget to
the pollutant's sources. For more information on TMDLs, visit EPA's website at www.epa.gov/owow/tmdl.
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Figure 1. Stratford aeration tank.
nitrogen reduction target. Without the TMDL, the nutrient
reduction target established by the LISS after years of research
and analysis would not have an enforceable implementation
mechanism. In addition, the nitrogen TMDL for the Long
Island Sound recommends flexible, innovative implementation
approaches, including nitrogen trading.
Who were the participating stakeholders and
key partners?
Development of TMDLs in the states of Connecticut and New
York is the responsibility of the CTDEP and the NYSDEC. To
develop the nitrogen TMDL for Long Island Sound, CTDEP
and NYSDEC worked through the LISS—a partnership of
federal, state, local government agencies, private organizations,
and educational institutions. TMDL implementation, unlike
TMDL development, is largely in the hands of stakeholders
and partners that can play a role in achieving pollutant load
reductions, depending on the actions recommended by the
TMDL. In the case of the Long Island Sound, a significant
portion of implementation activities have focused on upgrades to STPs in Connecticut
and New York to achieve nitrogen reductions. Figure 1 shows an aeration tank installed at
the Stratford (Connecticut) STP as part of the facility's upgrade to implement a biological
nutrient removal technique. Other LISS partners also provide funding for research and
implementation projects to address the hypoxia problem.
How did stakeholders participate in the TMDL process?
The overall TMDL process includes the following elements: CWA section 303(d) listing
decisions, TMDL development, and TMDL implementation. Each element of the TMDL
process provided stakeholders with an opportunity to express concerns and share
information about the water quality problems in the Long Island Sound with CTDEP,
NYSDEC, and other LISS partners. A description of each element of the TMDL process is
provided below.
Section 303(d) listing decisions
If a waterbody does not meet water quality standards for one or more pollutants, it
goes on a state's 303 (d) list. Impaired waterbodies on this list require a TMDL for each
pollutant contributing to the impairment. Stakeholders have the opportunity to provide
input during the 303(d) listing process. Extensive public involvement in the LISS in the
late 1980s and early 1990s provided stakeholder input into conditions in the Sound and in
identifying use impairments. Both CTDEP and NYSDEC placed the Long Island Sound on
their state's 303(d) list in 1992 due to low DO levels. According to the final TMDL report,
the low DO levels in the Sound led to impairments in bathing area quality, an increase in
unhealthy areas for aquatic marine life, an increase in mortality of sensitive organisms,
poor water clarity for scuba divers, a reduction in commercial and sport fisheries values, a
reduction in wildlife habitat value, degradation of seagrass beds, impacts on tourism and
real estate, and poorer aesthetics.
TMDL development
Established in 1985, the LISS conducted much of the research, monitoring, and computer
modeling of the Long Island Sound necessary for developing a TMDL to address low
DO. Years of research and monitoring helped the LISS to create a three-dimensional,
time variable, hydrodynamic and water quality model called the LIS 3.0 model. Using
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this model, the LISS analyzed the relationship among factors affecting DO levels and
demonstrated that nitrogen is the primary pollutant causing water quality impairments.
The LISS developed and, in 1998, adopted a plan entitled Phase IIIActions for Hypoxia
Management that recommended nitrogen reduction targets. The analysis conducted
for this plan focuses on identifying the sources of nitrogen in the Long Island Sound,
calculating the nitrogen load associated with these sources, and setting a numeric target
for reducing nitrogen to achieve Connecticut and New York's DO water quality standards.
The LISS identified municipal and industrial wastewater treatment facilities, combined
sewer overflows (CSOs), urban and agricultural runoff, and atmospheric deposition as
significant sources of nitrogen to the Sound. To identify nitrogen loads from these sources,
the LISS examined in-basin loads from 12 management zones and loads from tributaries
north of Connecticut. The analysis estimated that a total of 100,436 tons per year of
nitrogen reached the Long Island Sound from both in-basin and tributary sources, with 42
percent of that total load from municipal and industrial wastewater treatment facilities. Of
the total nitrogen load, approximately 53 percent originates from in-basin sources, with
in-basin point sources contributing 73 percent of the nitrogen load. Additional analysis
demonstrated that the current limit of technology on these sources in Connecticut and
New York would not fully achieve water quality standards. To improve DO levels to
meet water quality standards, the analysis showed that tributary nitrogen reductions and
management alternatives in addition to nitrogen removal would be necessary.
The TMDL development process integrated the analysis conducted to develop the Phase
III Actions for Hypoxia Management plan and used the 58.5 percent nitrogen reduction
target for in-basin sources as a basis for establishing a nitrogen budget among sources. In
addition, the final TMDL report identifies additional actions and schedules from sources
outside the basin and non-treatment alternatives necessary to achieve water quality
standards. The final TMDL report provides the nitrogen wasteload allocations (WLAs)
assigned to point sources, as well as the load allocations (LAs) assigned to nonpoint
sources, within each of the 12 management zones. The final TMDL report states that
point sources within a management zone have the opportunity to reallocate WLAs with
each other. Point sources in different management zones can also reallocate WLAs with
each other using an equivalency factor to account for nitrogen loss and impact on DO
levels in the Sound.
The final TMDL report states that addressing the tributary nitrogen sources located
outside of Connecticut and New York will require EPA to take the lead. The TMDL
analysis estimated that retrofit upgrades to STPs outside of the basin could reduce
nitrogen loads from these sources by 25 percent and nonpoint source runoff controls
could reduce nitrogen loads by 10 percent. In addition, Clean Air Act implementation
could reduce basinwide atmospheric nitrogen loads by 18 percent.
Developing the Phase III Actions for Hypoxia Management plan and the Long Island
Sound nitrogen TMDL included involving the public. For the Phase III plan, the LISS
mailed 4,000 copies of the plan to a wide range of stakeholders and conducted a series of
12 public meetings in Connecticut and New York. For the TMDL, CTDEP and NYSDEC
also mailed copies of the draft TMDL report to stakeholders and held a series of public
meetings. Through the formal public comment period, CTDEP and NYSDEC received 33
comment letters. In addition, CTDEP conducted a separate public involvement process for
the point sources assigned individual WLAs under the TMDL. This process, which was
intended to refine the Connecticut point source WLAs, resulted in six public meetings
attended by 120 participants as well as the submittal of 24 comment letters. The final
TMDL report reflected input provided by stakeholders on a variety of technical issues.
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TMDL implementation
Implementing the nitrogen TMDL for the Long Island Sound involves a five-phase,
iterative approach focused on action, assessment, and adjustment referred to as adaptive
management. Phases I, II, and III were precursors to the TMDL, developed by the LISS as
part of the Comprehensive Conservation and Management Plan initiated in 1988.
The LISS Phase I program placed a freeze on point and nonpoint nitrogen sources at
1990 levels to protect the Sound from further nitrogen pollution; the 1990 nitrogen levels
served as a baseline for the TMDL. The Phase II action plan went into effect in 1994 and
focused on implementing low-cost retrofits at selected STPs to reduce nitrogen loads. The
Phase III action plan, which provided the basis for the 58.5 percent nitrogen reduction
target in the TMDL, included a 15 year implementation schedule with three five-year
incremental targets. The Phase III action plan implementation schedule started in August
1999 and ends in August 2014. Actions under this phase focus on revisions to NPDES
permits for point sources and development of nonpoint source management plans. The
ability to reallocate nitrogen reductions among point sources, commonly referred to as
nitrogen trading, is a central component of the Phase III implementation activities.
Both Connecticut and New York have approaches in place to help point sources reallocate
their nitrogen WLAs under the TMDL. To facilitate nitrogen load reallocations,
Connecticut developed and issued a nitrogen general permit and created a Nitrogen
Credit Trading Program for the 79 STPs located throughout the state. New York devised
a bubble permit strategy to allow for flexibility in the upgrade construction scheduling
for STPs within the management zones established by the TMDL. This strategy
provides STPs with the flexibility to determine how best to meet the overall nitrogen
WLA applicable to a management zone. However, if the group of STPs exceeds a WLA
for a management zone, STPs are subject to the individual WLAs, as published in the
TMDL, for the purpose of compliance. The New York City (NYC) plants and permits are
somewhat different in that NYC has elected to meet all of the NYC-owned STP WLAs for
zones 8 & 9 with upgrades to only the STPs in Zone 8. Connecticut's program is expected
to save between $200 and $400 million in wastewater treatment construction costs over
the next ten years and New York's bubble permits are expected to save money as well. For
example, New York City is expected to save $660 million in STP upgrade costs.
The LISS publishes an annual implementation tracking report that includes activities
related to achieving the 58.5 percent nitrogen reduction target in the TMDL. According
to the 2007 report, between 2003 and 2007 Connecticut and New York reduced nitrogen
loads from point sources by 9,700 trade equalized (TE) pounds per day (Ibs/day). The
TMDL baseline load is 59,146 TE Ibs/day, with 39,700 TE Ibs/day discharged by 106
treatment plants as of December 2007. The 2014 TMDL goal is 22,774 TE Ibs/day.
Phase IV actions focus on achieving nitrogen reductions from sources located in states
north of Connecticut. Implementation actions under this phase will focus on developing
a nitrogen reduction program for upstream areas and implementing existing Clean Air
Act programs to reduce out-of-basin nitrogen loads to achieve the applicable DO water
quality standards. The New England Interstate Water Pollution Control Commission
(NEIWPCC) is assisting in TMDL implementation efforts by coordinating the effort to
better define nitrogen sources and loads in the Upper Connecticut River Basin. This effort
involves Connecticut, Massachusetts, New Hampshire, Vermont, and U.S. EPA.
Phase V actions include the review, evaluation, and implementation, as needed, of
non-treatment alternatives. The LIS will identify specific actions in a revised TMDL,
planned after the five-year evaluation under the Phase III implementation schedule, after
considering all in-basin and out-of-basin air and water controls.
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Under an adaptive management approach, the LISS has identified several opportunities
for reassessment and revision of the TMDL. The TMDL is currently undergoing revision
as part of the adaptive management approach.
What is the current status of the Long Island Sound as a result of the
TMDL process?
To track the health of the Long Island Sound over time, the LISS uses a suite of
environmental indicators based on recent chemical, biological, and physical data. The
focus of the nitrogen TMDL is to reduce nitrogen loads as a way to increase the levels of
DO in the Sound. Increased DO levels should decrease the number of days and the extent
of hypoxia in the Sound during the critical summer months. Because hypoxia is related
to both physical conditions and nutrient loadings, weather patterns affect the severity
of hypoxia that occurs from year to year. As a result, long term monitoring is needed to
identify trends over time. According to the LISS environmental indicators, the extent of
hypoxic conditions during 2007 was 162 square miles; the seventh least severe year since
1991. Hypoxia in the bottom waters lasted 58 days, one day above the average from 1987
through 2007. As discussed in the final TMDL report, attaining the DO water quality
standards will require further nitrogen reductions from both in-basin and out-of-basin
sources.
How did local stakeholders benefit from the TMDL process?
Implementing innovative nitrogen reduction approaches, including nitrogen credit
trading and nitrogen load reallocation under bubble permits, has helped point sources in
Connecticut and New York make significant progress toward achieving the 58.5 percent
nitrogen reduction goal for 2014. It is anticipated that these improvements, coupled with
nitrogen reductions from out-of-basin sources, will improve DO levels and reduce hypoxic
conditions in the Long Island Sound over time.
In addition to water quality benefits, the TMDL process and the innovative approaches
for achieving nitrogen load reductions promoted through the TMDL have benefitted
stakeholders in several ways.
O Increased cost savings while achieving nitrogen reductions. Upgrading STPs is an
expensive endeavor. During 2003-2007, Connecticut has upgraded 19 STPs for a cost
of $56.5 million. However, through Connecticut's Nitrogen Credit Exchange Program,
the upgrades generated $10.5 million worth of nitrogen credits in five years. This
program is expected to save between $200 and $400 million in wastewater treatment
construction costs over the next ten years. New York's bubble permits for management
zones are expected to save money as well. For example, New York City is expected to
save $660 million in STP upgrade costs.
O Improved water quality for recreation activities important to the regional
economy. Based on a 1992 study, recreational activities in the Long Island Sound are
estimated to contribute an annual revenue of more than $8 billion (inflation adjusted)
to the regional economy. As water quality improves, tourists are more likely to use the
Long Island for swimming and boating, generating more cash flow.
O Increased recognition for innovative approaches. The innovative approaches at
work in the Long Island Sound are the topic of many presentations, journal articles,
and case studies. In 2007, Connecticut's Nitrogen Credit Exchange received EPA's Blue
Ribbon Water Quality Trading Award for the program's outstanding accomplishments.
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O Increased access to funding. LISS partner agencies and organizations contribute
funding to support implementation activities that will achieve nutrient reductions and
achieve DO water quality standards in the Sound. Connecticut has provided hundreds
of millions of dollars in grants and loans through its Clean Water Fund to implement
nitrogen reductions. New York targeted $270 million in grant assistance for Long
Island Sound in the 1996 Clean Air/Clean Water Bond Act.
O Increased local, state, and regional partnerships. The LISS is a highly effective bi-
state partnership that involves state and federal agencies, concerned organizations,
and individuals. Through the TMDL process, the network of partnerships has grown.
Individual STPs collaborate with the states and other STPs to achieve nitrogen
load reductions. States north of Connecticut collaborate to establish out-of-basin
nitrogen reduction targets and identify strategies to achieve those targets. The public
participation processes for the TMDL process and the subsequent permitting activities
also generate partnerships within the Long Island Sound watershed.
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December 2009 • EPA841-F-09-002C
For more information on the Long Island Sound nitrogen TMDL, contact
Mark Parker, Connecticut Department of Environmental Protection
mark.parker@ct.gov, (860) 424-3276
Sarah Deonarine, New York State Department of Environmental Conservation
sndeonar@gw.dec.state.ny.us, (631) 444-0467
For more information on the Connecticut TMDL Program,
visit www.ct.gov/dep/cwp/view.asp?a=2719&q=325604&depNav_GID=1654
For more information on the New York TMDL Program, visit www.dec.ny.gov/chemical/31290.html
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