CHESAPEAKE BAY TIDAL WATERS DESIGNATED USES
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NOTE TO REVIEWERS: THIS DOCUMENT PRESENTS THE RESULTS OF WORK TO
DATE BY A TEAM OF ALL SIX STATES, DC AND EPA REGIONAL AND
HEADQUARTERS WATER QUALITY STANDARDS PROGRAM MANAGERS IN
DEFINING A REFINED SET OF CHESAPEAKE BAY TIDAL WATERS DESIGNATED
USES REFLECTIVE OF BAY LIVING RESOURCE NEEDS AND HABITATS. THE TIDAL
WATER DESIGNATED USES PRESENTED HERE SHOULD BE VIEWED AS WORKING
DRAFTS SUBJECT TO CHANGE DURING THE PLANNED MULTISTAGE REVIEW
PROCESS. WE ENCOURAGE COMMENTS, IDEAS, RECOMMENDATIONS, AND
EXPRESSIONS OF CONCERN FOCUSED PARTICULARLY ON THE APPROACH TAKEN
TO CHARACTERIZE THE DIFFERENT DESIGNATED USES AND ESTABLISH THE
BOUNDARY DELINEATIONS BETWEEN THE FIVE DESIGNATED USES.
APPENDIX A.
Refined Designated Uses for the Chesapeake Bay and
Tidal Tributary Waters
Acknowledgments
These Chesapeake Bay tidal waters designated uses were derived through the
collaborative efforts of the Chesapeake Bay Water Quality Standards Coordinators Team: Rich
Batiuk, U.S. EPA Chesapeake Bay Program Office; Jerusalem Bekele, District of Columbia
Department of Health; Iibby Chatfield, West Virginia Environmental Quality Board; Rich Eskin,
Maryland Department of the Environment; Tom Gardner, U.S. EPA Office of Water (Criteria);
Jean Gregory, Virginia Department of Environmental Quality, Denise Hakowski, U.S. EPA
Region 3; Elaine Harbold, U.S. EPA Region 3; Wayne Jackson, U.S. EPA Region 2; Jim
Keating, U.S. EPA Office of Water (Standards); Larry Merrill, U.S. EPA Region 3; Gary Miller,
U.S. EPA Region 3; Joel Salter, U.S. EPA Office of Water (Permits); John Schneider, Delaware
Department of Natural Resources and Environmental Control; Mark Smith, U.S. EPA Region 3;
Scott Stoner, New York Department of Environmental Conservation; and Carol Young,
Pennsylvania Department of Environmental Protection.
Without the contributions of well over a hundred individuals listed as authors or technical
contributors to various syntheses of Chesapeake Bay living resource habitat requirements over
the past two decades, the scientific basis for a set of designated uses tailored to Chesapeake Bay
tidal habitats and species would not have been forged. Their collective contributions are hereby
fully acknowledged.
Background
Existing state designated uses applied to Chesapeake Bay and tidal tributary waters
change across jurisdictional borders even for the same water body, the uses don't reflect natural
conditions, and are not specific enough to allow water quality criteria tailored to different

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habitats. The 2000 Chesapeake Bay Agreement and a subsequent six state/DC/EPA
memorandum of understanding challenged the Bay watershed jurisdictions to "by 2010, correct
the 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" (Chesapeake Executive Council, 2000). These agreements
included commitments to "define the water quality conditions necessary to protect aquatic living
resources" by 2001 and having the jurisdictions with tidal waters "use their best efforts to adopt
new or revised water quality standards consistent with the defined water quality conditions" by
2003. Against this backdrop of a renewed commitment to restore Bay water quality, in part,
through adoption of a consistent set of Chesapeake Bay water quality criteria as state standards, it
was determined that the underlying tidal water designated uses must be refined to better reflect
the restored Bay water quality conditions.
In refining the tidal water designated uses, five considerations were applied:
-	the designated uses must reflect a limited, select set of publicly understandable habitats and
intended aquatic life uses of those habitats;
-	habitats used by common sets of species and life stages should be identified and delineated as
separate designated uses;
-	natural variations in water quality must be directly reflected in the delineation of the
designated uses;
-	seasonal uses of different habitats need to be factored into the designated uses; and
-	the designated uses should be selected so that the Chesapeake Bay criteria for dissolved
oxygen, water clarity and chlorophyll a could be tailored to support each unique designated
use.
The resultant conceptual illustration of a set of refined tidal water designated uses addressing
these considerations is presented in Figure A-l.
This appendix describes a set of five refined tidal water designated uses and defines the
boundaries between "migratory spawning and nursery," "shallow water," "open water," "deep
water," and "deep channel" habitats. Accurate delineation of where to apply these tidal water
designated uses is critical as the Chesapeake Bay water quality criteria, particularly the Bay
dissolved oxygen criteria, will be applied differentially over time and space to the different
designated use habitats.
The publication of two extensive syntheses of the physical, water quality, and biological
habitat requirements of a set of commercially, recreationally and ecologically important target
species and communities laid the foundation from which these refined tidal water designated
uses were first conceived, then built (Chesapeake Bay Living Resource Task Force 1987;
Funderburk et al. 1991). Only when coupled with analyses of the extensive Chesapeake Bay
Water Quality Monitoring Program data base, now spanning 16 years, could the refined tidal
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water designated uses described below be documented and delineated across all tidal water
habitats without constraints by artificial jurisdictional borders.
Chesapeake Bay Tidal Waters Designated Uses
Migratory Spawning and Nursery
The migratory spawning and nursery designated use is the propagation and growth of
balanced indigenous populations of ecologically, recreationally, and commercially important
anadromous, semi-anadromous, and tidal fresh resident fish species inhabiting spawning and
nursery grounds from February 15th through June 10th.
Designated Use Rationale
Based on the commitment within the 1987 Chesapeake Bay Agreement to "develop and
adopt guidelines for the protection of water quality and habitat conditions necessary to support
the living resource found in the Chesapeake Bay," a list of target species were identified
(Chesapeake Executive Council, 1987). Included on that list of targeted species were striped
bass, American shad, hickory shad, alewife, blueback herring, white perch, and yellow perch
These anadromous and semi-anadromous fish were selected on the basis of their "commercial,
recreational, aesthetic, or ecological significance and the threat to sustained production due to
population decline or serious habitat degradation"(Chesapeake Bay Living Resources Task Force
1988).
Chesapeake Bay tidal waters support spawning areas and juvenile nurseries for a host of
anadromous and semi-anadromous fish, important to not only maintaining Chesapeake Bay
fishery populations, but also those of the entire East Coast for species like striped bass. The
eggs, larvae, and early juveniles of anadromous and semi-anadromous species have often more
sensitive habitat quality requirements than other species and life stages (Funderburk et al. 1991;
Jordan et al. 1992). For these reasons, the combined "migratory spawning and nursery" habitats
were delineated as a refined tidal water designated use for Chesapeake Bay.
Designated Use Boundary Delineation
The upper and lower boundaries of the "migratory spawning and nursery" designated use
are defined by the upper extent of tidally influenced waters down river/down Bay to the lower
reach of existing spawning and nursery habitats defined through a composite overlay of all
targeted anadromous and semi-anadromous fish species' spawning/nursery habitats (Figure A-2).
The designated use extends horizontally from the intertidal zone across the water body to
the adjacent intertidal zone and vertically down into the water column, either to the measured
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depth of the upper pycnocline boundary or, in the absence of a measured pycnocline, all the way
to the tidal tributary or mainstem Bay bottom sediments. During the February 15th through June
10th time period, the "migratory spawning and nursery" designated use encompasses the "shallow
water" and "open water" designated use habitats (see shaded sections in Figure A-l). Therefore,
the horizontal and vertical delineations for the "migratory spawning and nursery" designated use
directly matches with those of the "shallow water" and "open water" designated uses.
To generate these boundaries, the habitat distribution maps listed in Table A-l drawn
from the Habitat Requirements for Chesapeake Bay Living Resources - Second Edition
(Funderburk et al. 1991) were overlaid. When a single species had multiple habitat distribution
maps for related life stages, the maps were merged into a single coverage. After merging where
necessary, the individual species maps were overlaid and the number of overlapping habitat maps
were counted and visually displayed (Figure A-3).
The striped bass habitat distribution maps used in this overlay process were originally
titled "Striped Bass Chesapeake Bay Spawning Reaches and Spawning Rivers". The source of
the spawning reach distributions were research and monitoring findings synthesized by Setzler-
Hamilton and Hall (1991). However, the mapped extent of the nursery areas, termed spawning
rivers in the original map, were based on Maryland and Virginia legislative definitions, not
fisheries survey findings. Follow up discussions were held with Herb Austin and Deane Estes,
Virginia Institute of Marine Science, and Eric Durelle, Maryland Department of Natural
Resources, all fishery scientists responsible for their respective state's juvenile striped bass seine
surveys. Based on comparison of long term Maryland and Virginia seine survey data with the
legislatively defined extent of early juvenile nursery habitat, the primary nursery areas for young
of the year striped bass were delineated. Even though juvenile striped bass can be found
throughout a broader range of Maryland and Virginia tidal waters, the highest concentrations of
early juvenile life stage striped bass are found in the primary nursery areas illustrated in Figure
A-2 in the spring to early June time frame (e.g., Austin et al. 2000).
Critical Support (food, shelter) Comm unities
Spawning adults and the resultant larvae and early juvenile fish depend on an array of
phytoplankton, zooplankton, bottom dwelling worms and clams, and forage fish as prey within
the "migratory spawning and nursery" designated use habitat during these critical life stages
(numerous references cited in Funderburk et al. 1991) The presence of underwater grasses in the
shallow reaches of the designated use habitat are essential to providing a source of shelter for
young juveniles as well as a location of concentrated prey species.
Seasonal Use Application
The "migratory spawning and nursery" designated use applies from February 15th through
June 10th. From June 11th through February 14th, the shallow water and open water designated
uses apply to these same habitats (see Figure A-l). The defined season for application of the use
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is based on a composite of the full range of spawning periods and timing of when early juveniles
leave the nursery areas for all the target anadromous and semi-anadromous species. Adult yellow
perch migrate from downstream stretches of tidal water to spawning areas in less saline upper
reaches in mid-February through March (Richkus and Stroup 1987; Tsai and Gibson 1971). By
early June, young of the year juvenile striped bass begin to move shoreward, spending the
summer and early fall in shoal water less than six feet deep (Setzler-Hamilton et al. 1981). As
juveniles grow, they move progressively down river out of the nursery areas (Boreman and
Klauda 1988; Dey 1981; Setzler-Hamilton et al. 1981). The February 15th date was selected to
reflect the initiation of the yellow perch spawning season with the June 10th date selected to
reflect the time when many striped bass juveniles are heading down river/down Bay beyond the
lower boundaries of the designated use.
Applicable Chesapeake Bay Water Quality Criteria
From February 15th through June 10th, the "migratory spawning/nursery" dissolved
oxygen criteria, "shallow water" water clarity criteria, and "shallow/open water" chlorophyll a
criteria apply to the "migratory spawning/nursery" designated use habitats. See Chapters M, IV,
and V, respectively, for more details on the individual criteria.
Shallow Water
The "shallow water" designated use is the propagation and growth of balanced,
indigenous populations of ecologically, recreationally, and commercially important fish, shellfish
and underwater grasses inhabiting shallow water habitats.
Designated Use Rationale
The "shallow water" designated use is designed to protect a wide array species like
largemouth bass and pickerel inhabiting tidal fresh and low salinity habitats to speckled sea trout
(juvenile) in higher salinity areas to blue crabs that inhabit shallow water habitats covering the
full range of salinities encountered in Chesapeake Bay and its tidal tributaries. Underwater
grasses, a critical community protected by the designated use, provides a source of shelter and
food that makes shallow water habitats so unique and integral to the productivity of the Bay
ecosystem. The many Chesapeake Bay species, which depend on these shallow water habitats at
some point during their life cycle (numerous references cited in Funderburk et al. 1991), have
specific habitat requirements while within these shallow habitats, the best example being
underwater grasses. Given the unique nature of these habitats and their critical importance to the
Chesapeake Bay ecosystem, "shallow waters" were delineated as a refined tidal water designated
use for Chesapeake Bay.
Designated Use Boundary Delineation
Tidally influenced waters from the intertidal zone out to the two meter depth contour, as
measured at mean low water along all Chesapeake Bay and tidal tributary shorelines, defines the
upper and lower boundaries for the "shallow water" designated use (Figure A-4). The two meter
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depth contour was selected principally on the basis of being the depth to which underwater Bay
grasses could be restored in many of the tidal tributaries and mainstem Bay shallow water
habitats. Although historical underwater grass beds in Chesapeake Bay probably grew to 3
meters or more, the 2 meter depth contour was chosen following an extensive evaluation of grass
bed distributions in the past 30 years and anticipated restoration of light levels required to restore
viable shallow water habitats out to the 2 meter depth (Batiuk et al. 1992; Dennison et al. 1993;
Batiuk et al. 2000). The intertidal zone was selected as the upper boundary for the "shallow
water" designated use as some species of underwater grass can grow up into the intertidal zone
(Batiuk et al. 2000; Koch 2001).
The 2 meter depth contour GIS coverage delineating the "shallow water" designated use
is accessible via the Chesapeake Bay Program web site's data hub at
http://www.chesapeakebay.net.
[EDITOR'S NOTE: ADDITIONAL DOCUMENTATION ON THE 2 METER DEPTH
CONTOUR COVERAGE AND HOW IT WAS DEVELOPED WILL BE ADDED IN THE
NEXT DRAFT.]
Critical Support (food, shelter) Comm. unities
Phytoplankton, zooplankton, forage fish, and bottom dwelling worms and clams are food
for a wide array of fish, crab, and molluscan shellfish species inhabiting shallow water habitats
during part or all of their life stages. Water quality criteria necessary to fully support the
"shallow water" designated use must provide for the survival, growth and successful propagation
of quality prey communities in sufficient quantities.
Applicable Bay Water Quality Criteria
The "shallow water/open water" dissolved oxygen criteria apply all year round, the
applicable salinity regime-based chlorophyll a criteria apply only during the spring (March-May)
and summer (July-September) time frames, and the applicable salinity regime-based water clarity
apply during the appropriate Bay grasses growing season (April to October for tidal fresh,
oligohaline and mesohaline habitats and March to May and September to November for
polyhaline habitats). See Chapters III, IV, and V, respectively, for more details on the individual
criteria.
Open Water
The "open water" designated use is the propagation and growth of balanced, i ndigenous
populations of ecologically, recreationally, and commercially important fish and shellfish species
inhabiting open water habitats.
Designated Use Rationale
Given the natural temperature and salinity stratification of the open water column and the
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direct influence of this stratification on the relative distribution of Chesapeake Bay species,
waters located above the pycnocline can support a different community of species than deeper
waters during the late spring to early fall time frame. Several well known species that inhabit the
opens waters of the Chesapeake Bay and its tidal tributaries are menhaden, striped bass, and
bluefish. The habitat requirements and prey need of these species are also different from species
and communities inhabiting less oxygenated, deeper water habitats. (See the "deep water's"
Designated Use Rationale section below for relevant information on the effects of natural water
column stratification.). Based on these natural conditions and how they influence the distribution
of Bay species, "open waters" were delineated as a refined tidal water designated use for
Chesapeake Bay.
Designated Use Boundary Delineation
The boundaries for the "open water" designated use are tidally influenced waters
extending horizontally from the two meter depth contour (measured at mean low water) (Figure
A-5) across the water body to the adjacent two meter depth contour and vertically down into the
water column to either to the measured depth of the upper pycnocline boundary or, in the absence
of a measured pycnocline, to the bottom sediments (Figure A-6). Where a measured pycnocline
is present but does not represent a barrier to oxygen replenishment, the open water designated
use will extend all the way down to the bottom sediments (Figure A-7).
In part of the mainstem Bay south of the mouth of the Rappahannock River, the "open
water" designated use habitat extends all the way down to the bottom. Although this region can
exhibit relatively strong stratification, it exhibits little dissolved oxygen deficiency. Proximity to
the mouth of Chesapeake Bay allows for continuous replenishment of subpycnocline waters with
oxygenated ocean water (Figure A-8).
[EDITOR'S NOTE: OTHER PRELIMINARY ANALYSES INDICATE THAT DELINEATION
OF THIS AREA SHOULD BE POSSIBLY AS FAR SOUTH AS A LINE DRAWN FROM THE
BACK RIVER ACROSS THE BAY TO THE CHERRYSTONE INLET. FURTHER FOLLOW
UP ANALYSES OF BOTH THE 16 YEAR BAY WATER QUALITY MONITORING
PROGRAM DATA RECORD AND BAY WATER QUALITY MODEL MANAGEMENT
SCENARIOS TO BE RUN THIS SUMMER/FALL WILL BE UNDERTAKEN TO CONFIRM
THE AREAS WITHIN THE MAINSTEM BAY AND TIDAL TRIBUTARIES WHERE THE
OPEN WATER DESIGNATED USE EXTENDS ALL THE WAY TO THE BOTTOM IN THE
PRESENCE OF STRATIFIED CONDITIONS.]
Critical Support (food, shelter) Comm unities
Water column dwelling phytoplankton, zooplankton, and forage fish constitute the major
prey for the species that inhabit the Bay's open waters (numerous references cited within
Funderburk et al. 1991). Water quality criteria necessary to fully support the "open water"
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designated use must provide for the survival, growth and successful propagation of quality prey
communities in sufficient quantities.
Applicable Bay Water Quality Criteria
The "shallow water/open water" dissolved oxygen criteria apply all year round and the
applicable salinity regime-based chlorophyll a criteria apply only during the spring (March-May)
and summer (July-September) time frames to the open water designated use habitats. See
Chapters III and V, respectively, for more details on the individual criteria.
Deep Water
The "deep water" designated use is to protect the propagation and growth of balanced,
indigenous populations of ecologically, recreationally, and commercially important fish and
shellfish species inhabiting deep water habitats.
Designated Use Rationale
In a eutrophic system such as Chesapeake Bay, excess organic matter settles to the
bottom where it fuels microbial activity (e.g., Malone et al. 1986; Tuttle et al. 1987). The more
fuel, the more oxygen consumed and, where replenishment is restricted, the more severely
oxygen depleted is the water. There is evidence that hypoxic and anoxic conditions existed in
the deeper waters of the Bay prior to European settlement (Cooper and Brush 1991). These same
data give strong evidence that anthropogenic activity has increased the frequency and severity of
oxygen deletion in the Bay (Zimmerman and Canuel 1999).
Many parts of the Bay become vertically stratified seasonally because of depth-related
density differences within the water column. These differences in density are caused primarily by
differences in salinity and, to lesser degree, temperature. Fresh water flowing from the rivers
tends to float on top of denser saline water moving in from the ocean, and the gravitational force
of the down-Bay or down-river flow of freshwater causes a wedge of deeper, saltier water to
move up-Bay, up-river. Vertically, at some point in the water column, a zone of maximum
density difference is reached, sufficient to inhibit or prevent exchange between water above and
below it. This region is called the region of the pycnocline. In the summer months, respiration
by organisms living below the pycnocline can deplete concentrations of dissolved oxygen.
Because waters below the pycnocline are isolated from surface waters, dissolved oxygen levels
can decrease until they are stressful or lethal to higher organisms.
Formation of the pycnocline is a natural process and not directly related to man's
influence. Where stratification is common, the pycnocline generally forms at about the same
depth, within a meter or two, every year. It is generally shallower at the mouths of rivers and the
Bay and deeper at the heads of rivers and the bay. The effect of the pycnocline is also not the
same everywhere in the Bay and is influenced by local characteristics such as bathymetry,
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vertical and horizontal circulation patterns, and proximity to the ocean and fall line. In some
parts of the Bay and rivers, these factors create a more complex stratification pattern: a second
pycnocline is formed lower in the water column, dividing the water column into three layers. If a
region is contained by both the pycnocline above and by bathymetry laterally, it is even more
isolated from oxygen-replenishing water. In contrast, below-pycnocline areas below the
Potomac River to the mouth of the Bay are continuously replenished by flow from the ocean and,
therefore, naturally should not show extreme low dissolved oxygen effects from being isolated
from surface waters.
Bay anchovy is a target species whose egg and larval life stages are found within the
pycnocline waters (Keister et al. 2000; Rilling and Houde 1999; MacGregor and Houde 1996).
Blue crabs, oyster, softshell clam, hard clam, spot, croaker, flounder, and catfish are all species
that inhabit the near bottom waters within the deep water habitats (references cited within
Funderburk et al. 1991). These species have oxygen requirements that are different from species
inhabiting shallow and open water column habitats. Where they feed as well as the distribution
of their eggs and larvae, in the case of bay anchovy, are strongly influenced by natural features of
the water column like the pycnocline.
"Deep water" was delineated as a refined tidal water designated use for Chesapeake Bay
based combination of the unique nature of the pycnocline region as an important living resource
habitat as well as the transitional nature of the water quality conditions-temperature, salinity and
dissolved oxygen—between the warmer, less saline, more oxygenated surficial open water and
the physically segregated, cooler, more saline, often oxygen depleted deep channel waters.
Designated Use Boundary Delineation
"Deep water" designated use waters are defined as the tidally influenced waters located
between the measured depths of the upper and lower boundaries of the pycnocline in areas where
a measured pycnocline is present and represents a barrier to oxygen replenishment (Figures A-8
and A-9). There will be circumstances where "deep waters" extend from the upper boundary of
the pycnocline to the sediment bottom where a lower boundary of the pycnocline is not
calculated due to the depth of the water column.
Critical Support (food, shelter) Comm unities
Bottom dwelling worms and clams and reef inhabiting forage fish are all important food
sources for the fish and crabs inhabiting deep water habitats. Water quality criteria necessary to
fully support the "deep water" designated use must provide for the survival, growth and
successful propagation of quality prey communities in sufficient quantities.
Applicable Bay Water Quality Criteria
The "deep water" dissolved oxygen criteria apply from May through September whereas
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"shallow water/open water" dissolved oxygen criteria apply from October through April in "deep
water" designated use habitats.
Deep Channel
The "deep channel" designated use is to provide a refuge for balanced, indigenous
populations of ecologically, recreationally, and commercially important fish species that depend
on deep channel habitats for overwintering from October through April; and, from May through
September, the propagation and growth of benthic infaunal and epifaunal worms and clams that
provide food for bottom feeding fish and crabs.
Designated Use Rationale
During the first winter of life, populations of five important Chesapeake Bay species-
white perch, striped bass, Atlantic croaker, shortnose sturgeon, and Atlantic sturgeon-are
constrained to oligohaline and mesohaline regions (<20 ppt) in the upper Chesapeake Bay
mainstem. As juveniles during their first winter of life, these species are expected to seek out
warmer temperatures that occur in deeper channel waters below the thermocline. From October
through April, the deep channel habitats in the upper Bay adjacent to shallower summer and fall
time habitats should be considered important nursery habitats for young-of-the-year juvenile
white perch, striped bass, and Atlantic croaker (Pothoven et al. 1997) as well as Atlantic and
shortnose sturgeon (Miller et al. 1997; Secor et al. 2000; Welsh et al. 2000). During the coldest
months, the interaction between temperatures and salinity tolerances may result in a habitat
bottleneck ("habitat squeeze") forcing distributions of the juveniles into these deep channel
habitats seeking preferred temperatures. Unpublished data from the Maryland Environmental
Service indicate that a thermocline separating warmer deeper waters from colder overlaying
waters typically occurs at a 10 to 20 meter depth in the deep channel during the months of
October to February.
In Chesapeake Bay, researchers have determined the oxygen minimum to be in the
subpycnocline waters at the head of the deep trough in the northern Bay during the late spring to
early fall time frame (Smith et al. 1992). Isolated from aerated surface water, oxygen
concentrations in this region are the net result of excess oxygen consumption from nutrient
inputs over oxygen additions from advected ocean waters from far down-Bay. North of this
region, the trough shallows quickly and bottom waters become oxygenated as they mix with
aerated waters in the shoals. South of this region, subpycnocline waters are re-oxygenated
through mixing with oxygenated oceanic waters entering through the Bay mouth
Given the physical nature of the deep trough region leading to naturally severe oxygen
depletion during the summer as well as its unique refuge habitat role during cooler months of the
year, the "deep channel" was delineated as a refined tidal water designated use for Chesapeake
Bay.
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Designated Use Boundary Delineation
"Deep channel" designated use waters are defined as tidally influenced waters at depths
below the measured lower boundary of the pycnocline over and within isolated deep channels
(Figure A-l 0). In the mainstem Chesapeake Bay, the "deep channel" designated use habitat is
located along the deep central trough running north-south from the Chesapeake Bay Bridge near
Annapolis to the region near the mouth of the Potomac River (see Figure A-8). The "deep
channel" is defined laterally by bathymetry of the trough and vertically by the lower boundary of
the pycnocline above and the bottom sediments below.
[EDITOR'S NOTE: WORK IS UNDERWAY TO DOCUMENT AND MAP OUT OTHER
POSSIBLE DEEP CHANNEL DESIGNATED USE HABITATS IN THE LOWER POTOMAC
RIVER, THE SHIPPING ENTRANCE CHANNELS TO THE PATAPSCO
RIVER/BALTIMORE HARBOR, THE LOWER RAPPAHANNOCK, AND POSSIBLY
OTHER TIDAL RIVERS. MAPS AND ACCOMPANYING DOCUMENTATION WILL BE
PROVIDED IN THE NEXT DRAFT OF THE TIDAL WATERS DESIGNATED USES
DOCUMENT.]
These deep channels are sinks for excess organic material fueling oxygen consumption
and they are isolated from surface and oceanic sources of oxygen replenishment. Vertical
stratification in combination with gravitational and horizontal circulation often cause severe
oxygen deficiency to be manifested, when present, not as a gradually declining gradient, but by a
rapid drop-off in oxygen, beginning just below the pycnocline and extending to the bottom
(Smith et al. 1992).
Within the "deep channel" designated use, specific areas are delineated as a seasonal
anoxic region where conditions of extremely low (<1 mg/L) and no oxygen (<0.2 mg/L)
conditions are likely to persist throughout even under the best management conditions that can
be achieved. The seasonal anoxic region is defined generally as the deep bottom waters of the
central trough in the mainstem Bay described above. This includes subpycnocline waters below
about the 14 meter depth contour near the Bay Bridge where the deep trough begins sloping
down to below the 20 meter depth contour further south where the trough deepens and maintains
the deep depth to just below the mouth of the Potomac. The differences in depth as one heads
south from the Chesapeake Bay Bridge down the Bay towards the Potomac River mouth is due
to a gradual deepening of the depth of the pycnocline.
[EDITOR'S NOTE: OVER THE COURSE OF THE SUMMER AND FAT J,, A SERIES OF
CHESAPEAKE BAY WATER QUALITY MODEL MANAGEMENT SCENARIOS ARE
PLANNED TO BE RUN WHICH, ALONG WITH ADDITIONAL ANALYSIS OF THE 16
YEAR BAY WATER QUALITY MONITORING DATA RECORD, WILL BE USED TO
MORE SPECIFICALLY DEFINE AND MAP OUT THE MAXIMUM EXTENT OF THE
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SEASONAL ANOXIC REGION. ADDITIONAL DOCUMENTATION AND MORE
SPECIFIC MAPS WILL BE INCLUDED IN THE NEXT DRAFT OF THE TIDAL WATERS
DESIGNATED USE DOCUMENT. WE SPECIFICALLY INVITE COMMENT ON HOW TO
BEST DEFINE AND APPLY THE SEASONAL ANOXIC REGION.]
Critical Support (food, shelter) Comm unities
Bottom dwelling worms and clams provide are the principal food source to bottom
dwelling and feeding crabs and fish in the deep channel. Water quality criteria necessary to fully
support the "deep channel" designated use must provide for the survival of these prey
communities.
Applicable Bay Water Quality Criteria
The "deep channel" dissolved oxygen criteria apply from May through September and the
"shallow water/open water" dissolved oxygen criteria apply from October through April in "deep
channel" designated use habitats. In the seasonal anoxic region, there will be periods from May
through September when the "deep channel" dissolved oxygen criteria will be unattainable.
Implementation Procedures
[EDITOR'S NOTE: THE DESIGNATED USE IMPLEMENTATION PROCEDURES WILL
BE FURTHER FLESHED OUT OVER THE COURSE OF THE SUMMER. PLEASE
IDENTIFY IMPLEMENTATION ISSUES NOT OUTLINED BELOW. THE ULTIMATE
OBJECTIVE IS TO DEVELOP A SET OF PROCEDURES THAT WILL BE ADOPTED AND
USED CONSISTENTLY ACROSS ALL BAY TIDAL WATERS BY THE STATES WITH
TIDAL WATERS.]
Formally Delineating the Designated Use Boundaries
Migratory Spawning and Nursery
Table A-2 provides the specific navigational aids and landmarks as well as GIS
coordinates delineating the down river/down Bay lower boundary of the "migratory spawning
and nursery" designated use across all applicable tidal waters....
[EDITOR'S NOTE: THE INFORMATION FOR TABLE A-2 IS CURRENTLY BEING
GENERATED BY THE CHESAPEAKE BAY PROGRAM OFFICE'S GIS TEAM AND WILL
BE CONFIRMED BY MD, VA, DC, AND DE FISHERY SCIENTISTS THIS SUMMER. THE
COMPLETE DETAILED TABLE WILL BE PUBLISHED IN THE NEXT DRAFT OF THE
TIDAL WATER DESIGNATED USE DOCUMENT.]
[SOURCE OF THE GIS COVERAGE TO BE ADDED AND DOCUMENTED.]
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CHESAPEAKE BAY TIDAL WATERS DESIGNATED USES
WORKING DRAFT No. 1	July 3, 2001
Shallow Water
[SOURCE OF THE GIS COVERAGE TO BE ADDED AND DOCUMENTED.]
Open Water/Deep Water/Deep Channel
[DETAILS AND ASSOCIATED PROGRAMMING FOR CALCULATING THE UPPER AND
LOWER BOUNDARIES OF THE PYCNOCLINETO BE ADDED AND DOCUMENTED.]
Seasonal Anoxic Region
[SOURCE OF THE GIS COVERAGE TO BE ADDED AND DOCUMENTED.]
Bay Criteria Implementation by Designated Use
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WORKING DRAFT No. 1	July 3, 2001
References
Batiuk, R.A., P. Berg^trom, M. Kemp, E. Koch, L. Murray, J.C. Stevenson, R. Bartleson, V.
Carter, N.B. Rybicki, J.M. Landwehr, C. Gallegos, L. Karrh, M. Naylor, D. Wilcox, K.A. Moore,
S. Ailstock, and M. Teichberg. 2000. Chesapeake Bay submerged aquatic vegetation water
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CBP/TRS 245/00 EPA 903-R-00-014. USEPA Chesapeake Bay Program, Annapolis, MD.
Batiuk, R., R. Orth, K. Moore, J. C. Stevenson, W. Dennison, L. Staver, V. Carter, N. Rybicki,
R. Hickman, S. KollarandS. Bieber. 1992. Submerged aquatic vegetation habitat requirements
and restoration targets: a technical synthesis. CBP/TRS 83/92. USEPA Chesapeake Bay
Program, Annapolis, MD.
Chesapeake Executive Council. 2000. 2000 Chesapeake Bay Agreement, Annapolis, MD.
Chesapeake Executive Council. 1987. Chesapeake Bay Agreement. Annapolis, MD.
Chesapeake Bay Living Resources Task Force. 1987. Habitat requirements for Chesapeake Bay
living resources: a report from the Chesapeake Bay Living Resources Task Force. Chesapeake
Bay Program, Annapolis, MD.
Cooper, S.R. and G.S. Brush 1991. Long term history of Chesapeake Bay anoxia. Science, 254:
992-996.
Dennison, W. C., R. J. Orth, K. A. Moore, J. C. Stevenson, V. Carter, S. Kollar, P. W. Bergstrom
and R. A. Batiuk. 1993. Assessing water quality with submersed aquatic vegetation. Habitat
requirements as barometers of Chesapeake Bay health. Bioscience. 43: 86-94.
Funderburk, S.L., J.A. Mihursky, S.J. Jordan, and D. Riley (eds.).1991. Habitat requirements for
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Koch, E.W. 2001. Beyond light: physical, geological, and geochemical parameters as possible
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Keister, J.E., E.D. Houde and D.L. Breitbuig. 2000. Effects ofbottom-layer hypoxia on
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MacGregor, J. and E.D. Houde. 1996. Onshore-offshore pattern and variability in distribution
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Malone, T.C., W.M. Kemp, H.W. Ducklow, W.R. Boynton, J.H. Tuttle, and R.B. Jonas. 1986.
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Welsh, S.A., J.E. Skjeveland, M.F. Mangold, and S.M. Eylver. 2000. Distribution ofwild and
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Chemistry, 69: 117-137.
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Table A-l. Migratory spawning and nursery habitat distribution maps used in the delineation of
the migratory spawning and nursery designated use.	
Alewife spawning and nursery
Alewife nursery
American shad spawning and nursery
American shad nursery
Hickory shad spawning and nursery
Herring spawning and nursery
Herring nursery
Striped bass spawning reaches
Striped bass spawning rivers
White perch nursery
White perch spawning
Yellow perch spawning and nursery	
Source: Funderburk et al. 1991.
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