Defining Restored Bay Water Quality from the Perspective of Fish, Crabs, Oysters and Underwater Gras

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Defining Restored Bay Water Qualityfrom the
Perspective of Fish, Crabs, Oysters and
Underwater GrassesChesapeake Bay Dissolved
Oxygen, Water Clarity and Chlorophyll a Criteria
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Impaired Waters and Clean-up Plans
Portions of the Chesapeake Bay and its tidal
rivers are listed under the Clean Water Act as
impaired waters largely because of low
dissolved oxygen levels and other problems
related to nutrient pollution.
Impaired Water
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Chesapeake 2000 The New Agreement
In June 2000, the Chesapeake Bay Program partners
signed a new agreement to guide the restoration
and protection of the Bay through the next decade
and beyond. In Chesapeake 2000, the partners
agreed that
Improving water quality is the most critical
element in the overall protection and restoration
of the Chesapeake Bay and its rivers.
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Chesapeake Bay Watershed Partners

• Signatories to the Chesapeake Bay agreement
• EPA (representing the Federal government)
• Jurisdictions of MD, PA, VA and DC
• Chesapeake Bay Commission (representing MD, PA
  and VA state legislatures)

• Headwater states
• DE, NY and WV
• Memorandum of Understanding linked to water
  quality goals

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Chesapeake 2000 AgreementWater Quality
Protection and Restoration

• Integrate cooperative Chesapeake Bay
• Program and statutory Clean Water Act
  processes.
• By 2010, correct the nutrient- and
  sediment-related
• problems in the Chesapeake Bay and its tidal
  
• tributaries and
• Remove the Bay and tidal tributaries from the
  list
• of impaired waters under the Clean Water Act.

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Chesapeake 2000 AgreementWater Quality
Protection and Restoration

• Define the water quality conditions necessary
  to
• protect aquatic living resources.
• Jurisdictions with tidal waters will use their
  best
• efforts to adopt new or revised water quality
• standards consistent with the defined water
• quality conditions.
• Use the standards as the basis for removing
  the
• Bay and its tidal rivers from the list of
  impaired
• waters.

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Refined Designated Uses forChesapeake 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
Migratory Fish Spawning and Nursery Use
Open-Water Habitat
Shallow-Water Bay Grass Use
Deep-Water Seasonal Fish and Shellfish Use
Deep-Channel Seasonal Refuge Use
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Restored Tidal Water Quality Means

• Fewer algae blooms and better fish food.
• Clearer water and more underwater Bay grasses.
• More oxygen and improved habitat for more fish,
  crabs and oysters.

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Chesapeake Bay Water Quality Criteria

• Dissolved Oxygen for fish, crabs and oysters
• Water Clarity light for underwater Bay grasses
• Chlorophyll a base of the Bay food chain

Together, these three criteria define the
conditions necessary to protect the wide variety
of the Bays living resources and their habitats.
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Dissolved Oxygen

• Living things--even those underwater--need
  oxygen!
• The amount of oxygen needed in the water depends
  on the specific needs of the Bays living
  resources.
• The amounts depend on where and when certain
  areas are used by different living resources.

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Oxygen Requirements (mg/L) of Bay Species
Migratory Fish Spawning Nursery Areas
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Striped Bass 5-6
American Shad 5
Shallow and Open Water Areas
5
White Perch 5
Yellow Perch 5
4
Hard Clams 5
Deep Water
Alewife 3.6
3
Bay Anchovy 3
Crabs 3
2
1
Spot 2
Deep Channel
Worms 1
0
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Basis for Bay Dissolved Oxygen Criteria

• 1992 Chesapeake Bay oxygen restoration goal laid
  basic foundation
• 2000 EPA marine and 1985 EPA freshwater dissolved
  oxygen criteria documents
• Addition of more Bay species effects data
• Application of larval recruitment model using Bay
  specific parameters, species
• Authored by a team of Bay region scientists,
  state agency and federal agency technical staff

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Oxygen Criteria Derivation for Shallow/Open
Water Designated Use
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Chesapeake Bay Dissolved Oxygen Criteria
1. At temperatures gt29oC, dissolved oxygen
concentrations above instantaneous minimum of 4.3
mg/L will protect shortnose sturgeon.
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Water Clarity

• All plants--even those underwater--need light!
• Water clarity is a measure of the amount of
  sunlight that penetrates the Bays waters and
  reaches the surface of underwater Bay grass
  leaves.
• The amount needed is determined by the specific
  underwater grasses which grow in different areas
  of the Bay.

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Whats Blocking the Light?
Good Water Clarity
Poor Water Clarity

• Percent of sunlight at the water surface that
  penetrates the water
• 13 in low salinity waters
• 22 in high salinity waters

Sediment and other particles in the water

Algae in the water

Algae on the leaves
equals
Very low percentage of sunlight reaching leaves
Bay grasses grow poorly or die.
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Basis for Bay Water Clarity Criteria

• Two past technical syntheses (1992, 2000) of
  Chesapeake Bay underwater grasses habitat
  requirements
• Focus on light available to the underwater
  grasses at the leaf surface
• 18 year tidal WQ monitoring database
• Investments in ecosystem processes modeling

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Percent Light Parameters for Evaluating Ambient
Conditions
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Chesapeake Bay Water Clarity Criteria

• The criteria apply to Chesapeake Bay Program
  segment-specific depths up to two meters.
• Areas where underwater bay grasses never occurred
  or where natural factors, such as currents and
  wave action, prevent its growth are excluded.
• Water clarity criteria only apply to
  shallow-water bay grass designated use.

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Watershed partners have adopted a new 185,000
acre Bay grasses restoration goal Water
clarity criteria apply in the shallow water
habitats at depths needed to restore grasses to
these areas.
New Bay Grasses Restoration Goal
Baltimore
Washington DC
Cambridge
Fredericksburg
Richmond
Norfolk
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Chesapeake Bay Water Clarity Criteria for
Application to Shallow-Water Bay Grass Designated
Use Habitats
Example If a state chooses to use Secchi depth
for criteria application at 1.5 meter depth, the
criteria equivalent to 13 and 22 PLW is 1.1 and
1.4 meters, respectively.
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Chlorophyll a

• Chlorophyll a is a measure of the amount of algae
  in the water.
• Some algae are good sources of fish food and
  others are poor sources.

• Excessive nutrients can stimulate nuisance algae
  blooms resulting in reduced water clarity,
  reduced amounts of good fish food, and depleted
  oxygen levels in deeper waters.

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Chlorophyll a Criteria Components

• Based on fish food/algal composition
  quantification across an array of poor to good
  water quality conditions
• Narrative criteria to protect against adverse
  algal-related impacts on water quality
• Chlorophyll a concentrations characteristic of a
  range of water quality conditions and protective
  against specific water quality impairments have
  been published
• Concentration are applied as
• Salinity regime based
• Spring, summer medians

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Chesapeake BayNarrative Criteria for Chlorophyll
a
Concentrations of chlorophyll a in
free-floating 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.
Source U.S. EPA. 2003.
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Chesapeake Bay Criteria Guidance for Chlorophyll
a Criteria
EPA expects states to adopt narrative
chlorophyll a criteria into their water quality
standards for all Chesapeake Bay and tidal
tributary waters. EPA strongly encourages states
to develop and adopt site-specific numerical
chlorophyll a criteria for tidal waters where
algal-related impairments are expected to to
persist even after the Chesapeake Bay dissolved
oxygen and water clarity criteria have been
attained.
Source U.S. EPA. 2003.
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Chlorophyll a Criteria Supporting Technical
Information

• Based on fish food/algal composition
  quantification across an array of poor to good
  water quality conditions
• Phytoplankton growth limiting water quality
  conditions and and related chlorophyll a
  concentrations
• Concentration characteristic of potentially
  harmful algal blooms
• Concentrations characteristic of trophic-base
  conditions
• Concentrations protective against water quality
  impairments (water clarity, dissolved oxygen,
• Methodologies for deriving water body specific
  chlorophyll a criteria
• Salinity regime based, focused on spring, summer
  medians with maximum concentrations addressing
  algal blooms

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Illustration of Chlorophyll a, Food Quality, and
Water Quality Relationships
Scientists View
Chlorophyll Concentration
Biomass of Edible Phytoplankton
Biomass of Inedible Phytoplankton
Water Quality Worst Poor
Better Best
Restored
Poor Water Clarity Excess Nutrients
Good Water Clarity Low Nutrients
Corresponding Phytoplankton Food Value
Poor
Good
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Application of NumericalChlorophyll a Criteria

• The narrative criteria describes the various
  possible impacts on tidal Bay habitats due to too
  much algae and the wrong types of algae.
• Supporting target concentrations will be used by
  the states to establish numerical chlorophyll a
  criteria to address localized algal-related
  problems which are expected to persist even after
  the Chesapeake Bay dissolved oxygen and water
  clarity criteria have been attained.

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Chesapeake Bay Water Quality Criteria
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Criteria Implementation Procedures
A detailed set of criteria implementation
procedures have been developed addressing

• Magnitude
• Duration
• Frequency
• Space
• Time

For determining criteria attainment.
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Proposed Approach for Defining Attainment

• Develop an analytical tool that uses available
  data to account for spatial and temporal
  variability in criteria exceedence.
• Develop Cumulative Frequency Diagram (CFD).
• Develop a precise rule for deciding if a given
  segment is attaining its designated use.

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Steps for Developing a CFD
Step 1 Interpolate the Bay water quality
monitoring data for each sampling event (e.g.,
cruise) ? Station
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Step 2. Evaluate interpolated WQ monitoring data
interpolator cell by cell using the appropriate
criterion value
Criterion by Salinity
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Step 3. Identify the cells in a CBP segment /
designated use area that exceed the criteria for
each sampling event
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Step 4. Repeat Step 3 for each sampling event in
assessment period ...

March 1999 April 1999 May 1999 June 1999 March
2000 Apr 2000 May 2000
Assessment Period
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Step 4. to generate an event by event accounting
of area (volume) of a segment exceeding the
criteria

March 1999 April 1999 May 1999 June 1999 March
2000 Apr 2000 May 2000
Assessment Period
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Step 5. Compile the measures of area (volume)
exceeding the criteria. This quantifies the
SPATIAL EXTENT of the exceedences in a segment
for each sampling event.
Area (Volume) Exceeding
Example Assessment Over A Three Year Assessment
Period
Month
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Step 6. Sort and rank the measures of
area/volume of criteria exceedence
Area (Volume) Exceeding
Month
Example Assessment Over A Three Year Assessment
Period
Rank
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Step 6. and calculate the cumulative
probability values based on the ranks
Cumulative Probability (Rank/n1)
Area (Volume) Exceeding
Rank
Month
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Step 7. Plot the area in exceedence vs.
cumulative probability over time
Example Assessment Over A Three Year Assessment
Period
April 2000 X39, Y62
Time the Given Area/ Volume is in
exceedence
May 1998 X 65, Y 31
Area/Volume in Exceedence
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Step 7. Plot the area in exceedence vs.
cumulative probability over time
Example Assessment Over A Three Year Assessment
Period
at least 39 of the area exceeds the criteria in
62 of the sampling events during the three year
assessment period
Time the Given Area/ Volume is in
exceedence
at least 65 of the area exceeds the criteria in
31 of the sampling events during the three year
assessment period
Area/Volume in Exceedence
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Definition of Criteria Attainment
CFD Curve
Biologically-Based Reference Curve
0
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Definition of Criteria Attainment
Area of Criteria Exceedence
Area of Allowable Criteria Exceedence
0
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More Information is Available
The following products are available
athttp//www.chesapeakebay.net/baycriteria.htm

• Ambient Water Quality Criteria for Dissolved
  Oxygen, Water Clarity and Chlorophyll a for the
  Chesapeake Bay and its Tidal Tributaries (U.S.
  EPA 2003)
• Bay specific dissolved oxygen, chlorophyll a, and
  water clarity criteria published as EPA regional
  water quality criteria
• Baywide implementation guidelines for each of the
  three criteria

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More Information is Available
The following products are available
athttp//www.chesapeakebay.net/uaasupport.htm

• Technical Support Document for the Identification
  of Chesapeake Bay Designated Uses and
  Attainability (U.S. EPA 2003)
• Technical support document providing extensive
  information on attainability of current and
  refined tidal water designated uses
• Detailed documentation on refined tidal
  designated uses and recommended use boundaries