CBP Principals’ Staff Committee Meeting Lancaster, Pa. April 30, 2010

1. Bay Water Quality Responses to Simulated Nutrient and Sediment Load Reductions: Findings and RecommendationsPresentation VIII-A CBP Principals’ Staff Committee Meeting Lancaster, Pa. April 30, 2010 Bob Koroncai Lewis Linker USEPA

2. Presentation Preview • Nutrients: Dissolved Oxygen and Chlorophyll ‘a’ Criteria Attainment • Past decisions • Current model results • Next steps toward full attainment: decision • Sediment: Clarity and SAV Attainment • Current model results • Next steps towards full attainment: decision

3. Remember, in October 2009 the PSC agreed to a basin-wide target loads of… 15 mpy Phosphorus 200 mpy Nitrogen

4. PSC Told in October The Recommended Basinwide Loads Will Change Due to… • Updated critical period • Upgraded watershed model (Phase 5.2 to 5.3) • Filter feeder inclusion in the WQ model • Atmospheric deposition allocation and impact on ocean load • Modified assessment procedures for Bay criteria • SAV/clarity target load analysis • Trade-offs between N and P • Loading reductions needed to meet local Bay segments

5. DO Stoplight Plot Summary Information Violation Count >1% for the ’93-’95 Critical Period

6. DO Non-attainment – All Scenarios Violation counts based on >1% for the ’93-’95 critical period

7. Deep-Channel Use Dissolved Oxygen at Current Target Loads (200 TN, 15 TP+ 15.7 air allocation) • Non-attainment in 3 segments (>1%) • CB4 (2%) • Lower Chester (14%) • Eastern Bay (4%) • 1 segment at <1% • Reaching attainment will require further reductions in nutrient loads from larger Bay watershed

8. Deep-Water Use Dissolved Oxygen at Current Target Loads (200 TN, 15 TP+ 15.7 air allocation) • Non-attainment in 2 segments (>1%) • Lower Chester River (3%) • Magothy (16%) • 4 segments at <1% • Reaching attainment will require further reductions in nutrient loads from basinwide and local watershed scales

9. Open-Water Use Dissolved Oxygen at Current Target Loads (200 TN, 15 TP+ 15.7 air allocation) • Non-attainment in 15 segments (>1%), ex: • Pocomoke (25%) • Anacostia (16%) • Wicomico (15%) • Severn (6%) • Lower York (3%) • 8 segments at <1% • Reaching attainment will require further reductions in nutrient loads from local watershed scales

10. Dissolved oxygen/chlorophyll:where do we go from here? • Identify loads to achieve full attainment • Identify non-attaining segments • For each non-attaining segment: • Identify watershed(s) having the most influence on tidal water quality • Identify loadings needed to fully attain • Understand any other factors contributing to sustained non-attainment (beyond E3) • PSC agreement with this approach?

11. What about sediment?

12. Clarity/SAV Non-attainment Violation counts based on >1% for the ’93-’95 critical period

13. Clarity/SAV:where do we go from here? • Confirm assessment procedures fully consistent with states’ WQ standards regulations • Identify loads to achieve full attainment • Identify non-attaining segments • For each non-attaining segment: • Diagnosis major contributor(s) to reduce water clarity: nutrient, sediments • Identify watershed(s) having the most influence on tidal water quality • Identify loadings needed to fully attain • Understand any other factors contributing to sustained non-attainment (beyond E3) • PSC agreement with this approach?

14. When? • State/basin nutrient allocations by July 1 • State/basin sediment allocations by August 15

15. Nutrient and Sediment Summary • Need to refine state/basin nutrient allocations by meeting WQS in ‘local’ segments • Much sediment attainment achieved with P controls planned • Need to commit to extensive review in June (N/P) and July/August (S)

16. Questions?