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Refined Designated Uses for Chesapeake Bay and Tidal Tributary Waters

Defining Restored Bay and Tidal Tributary Water Quality  Round Two  Draft Revised Oxygen, Water Clarity and Chlorophyll Criteria. Refined Designated Uses for Chesapeake Bay and Tidal Tributary Waters. A. Cross Section of Chesapeake Bay or Tidal Tributary. Shallow Water. Open Water.

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Refined Designated Uses for Chesapeake Bay and Tidal Tributary Waters

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  1. Defining Restored Bay andTidal Tributary Water QualityRound TwoDraft Revised Oxygen, Water Clarity and Chlorophyll Criteria

  2. Refined Designated Uses for Chesapeake Bay and Tidal Tributary Waters A. Cross Section of Chesapeake Bay or Tidal Tributary Shallow Water Open Water Deep Water Deep Channel B. Oblique View of the “Chesapeake Bay” and its Tidal Tributaries Migratory Finfish Spawning and Nursery Habitat Open Water Habitat Shallow Water Habitat Deep Water Deep Channel

  3. Refined Designated Uses • Migratory Spawning & Nursery Waters: • tidal freshwater to low salinity habitats in the upper reaches of many Bay tributaries, Susquehanna flats, and upper main Bay • supports a wide array of migratory fish during late winter to spring spawning season • “Fish Spawning Habitat” • Shallow Water: • nearshore habitat; primary focus on underwater grasses • supports a wide variety of fish and crabs • “Bay Grass Habitat”

  4. Refined Designated Uses(continued) • Open Water: • surface water habitats, extending from shallow shoreline areas across tidal rivers and main Bay • supports diverse populations of sportfish and baitfish • “Finfish Habitat” • Deep Water: • transitional water column habitat between well mixed surface waters and very deep, narrower channels • supports fish like bay anchovy as well as many bottom feeding fish, crabs and other shellfish • “Shellfish Habitat”

  5. Refined Designated Uses(continued) • Deep Channel: • very deep channel habitats • low dissolved oxygen levels prevail during summer months • important summer location of food for bottom feeding fish and crabs; winter refuge habitat for many fish species • includes seasonal anoxic “exclusion” zones, where natural conditions cause complete lack of dissolved oxygen • “Seasonal Refuge Habitat”

  6. Migratory Spawning and Nursery Habitat Spawning and Nursery Habitat Source: Funderburk et al. 1992. Habitat Requirements for Chesapeake Bay Living Resources Revised Edition. Chesapeake Bay Program, Annapolis, MD.

  7. Water Quality Criteria • Dissolved Oxygen - necessary for all aquatic living resources • Water Clarity - key factor for underwater grass growth/survival • Chlorophyll - indicates algae levels, “fish food” value, and overall water quality

  8. Minimum Amount of Oxygen (mg/L) Needed to Survive by Species Draft Bay Dissolved Oxygen Criteria 6 Migratory Spawning & Nursery Areas Striped Bass: 5-6 American Shad: 5 5 Shallow and Open Water Areas White Perch: 5 Yellow Perch: 5 4 Hard Clams: 5 Deep Water Alewife: 3.6 3 Bay Anchovy: 3 Crabs: 3 2 Deep Channel 1 Spot: 2 Worms: 1 0

  9. Summer Dissolved Oxygen

  10. Current Draft Tidal Water Designated Uses Draft Dissolved Oxygen Criteria Deeper waters allowed lower DO levels during summer

  11. Draft Bay Water Clarity Criteria Good Water Clarity Poor Water Clarity Sediment and other particles in the water • Percent of sunlight through water: • 13% in low salinity waters • 22% in high salinity waters + Algae in the water + • Percent of sunlight reaching leaves: • 9% in low salinity waters • 15% in high salinity waters Algae on the leaves equals Very low percentage of sunlight reaching leaves – Bay grasses grow poorly or die.

  12. Bay Chlorophyll Criteria Based on Restoring Good Fish Food Where the Bay and rivers are now Bay Chlorophyll Criteria Too Much of the Wrong Green Stuff Right Green Stuff for Fish Food Water Quality Worst Best Poor Water Clarity Excess Nutrients Good Water Clarity Low Nutrients Corresponding Fish Food Value Poor Good

  13. Comparing Draft Chlorophyll Criteria with Monitoring Data Draft Criteria (ug/l):

  14. Chesapeake Bay Criteria Needed for Protection of the Proposed Tidal Waters Designated Uses Dissolved Oxygen Chlorophyll Water Clarity Migratory Spawning and Nursery * Shallow Water * * Open Water * * Deep Water * Deep Channel *

  15. Bay Criteria Schedule • July-Sept 2001 - first round of CBP partners review • May-July 2002 - second round of CBP partners/ stakeholders review; independent peer review • Oct-Nov 2002 - third round of review • Jan 2003 - EPA publication of Bay criteria • 2003/2004 - State adoption (MD, VA, DE, DC) of Bay criteria, refined uses as WQ standards

  16. Final Products • Bay-specific oxygen, chlorophyll, and clarity criteria published as EPA regional water quality criteria • Baywide guidelines for application defining attainment of each of the three criteria • Consistent tidal designated uses across states published as part of the criteria document

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