Assessing Bay Criteria

1. Assessing Bay Criteria Assessment method reminder ‘Relative Model’ method Direct model assessment Results

2. Criteria Assessment

3. Gather and interpolate WQ Data

4. Separate Open Water from Deep Water from Deep Channel using the pycnocline

5. Assess violations of the criterion each month for three years March 1999 April 1999 May 1999 June 1999 March 2000 Apr 2000 May 2000 Assessment Period

6. Unallowable exceedences Allowable exceedences Create and Evaluate the CFDs

7. Dissolved Oxygen Criteria • Green – evaluated using data • Otherwise not evaluated for 303d

8. 2003 DO Criteria Assessment • Use the model in a relative sense to re-generate ‘observed’ data sets for different scenarios • Model output not directly assessed • Model response to scenarios overlaid on observed data to create “what we would have observed given scenario inputs”

9. Model E3 Scenario Calibrated Model Modeling Team 1985 - 1994 Observed Data E3 “Observations” Monitoring Team Monitoring Team Observed Criteria Achievement Criteria Achievement Under E3

13. [E3] = 0.8 * [calibration] + 1.5

16. One regression for each pointfor each month

17. 2008 Proposed MethodDO Criteria Assessment • 2003 method – use the model in a relative sense to re-generate ‘observed’ data sets • Direct assessment from the model

18. Model E3 Scenario Calibrated Model Criteria Achievement Directly Evaluated For all criteria Modeling Team 1991 - 2000 Observed Data E3 “Observations” Monitoring Team Monitoring Team Criteria Achievement For 8 3-year periods Criteria Achievement Under E3

19. Proposed DO Criteria Assessment • Use the direct model assessment to determine whether the 3 relative-model assessments are more or less difficult to achieve • Question 1 – Which criteria are ‘limiting’? • Use the model in a relative sense (2003 method) for the TMDL • Question 2 – What is the TMDL?

20. 1996-1998 244/21 Calibration - 340/24 146/13

21. 1996-1998 Assessable Criteria are Limiting!! 244/21 Calibration - 340/24 146/13

22. Monthly is Limiting in all Deep Water Cases Trib Strategy Model direct output 1996-1998

23. Monthly is Limiting in all Open Water Cases Trib Strategy Model direct output 1996-1998 Plus 26 more monthly limited Plus 66 More no violation

24. Change among 3-year periods

27. Initial Observations • Model predicts that the most restrictive criteria are the ones that we can measure and assess through the relative model method • The relative model method is sensitive to load reductions

28. Decision Requested • Agreement on proceeding forward with the recommended procedures for assessing the full suite of Bay criteria adopted by the states into their water quality standards regulations pending further understanding of which sets of criteria are driving the allocations.