Chesapeake Bay Program Reevaluation Technical Workgroup Conference Call July 3, 2008 SUMMARY OF DECISIONS, ACTIONS AND ISSUES Finalizing the Bay Criteria Attainment Assessment Procedures for Application to the Bay Water Quality/Sediment Transport Model Output: Dissolved Oxygen and Chlorophyll a Gary Shenk reviewed Attachment A. providing the group with background information on applying criteria assessment procedures and asking for the requested decisions. ¦ In the 2003 allocation process, three dissolved oxygen (DO) criteria were used for setting goals, the only 3 that could be adequately assessed. These criteria attainment procedures included an open-water 30-day mean, deep-water 30-day mean, and deep- channel instantaneous minimum for DO and seasonal chlorophyll a criteria attainment. ¦ The Chesapeake Bay Water Quality Model output was used only in a relative sense to generate modified monitoring data in order to assess attainment under a variety of management scenarios. ¦ The partners have agreed upon the updated criteria assessment procedures which were updated since 2003 and used for the 2008 303(d) lists. ¦ The Criteria Assessment Protocols Workgroup has produced a draft addendum to document the recent revisions to states' 303(d)/305(b) assessment and listing procedures. ¦ For the past two 303(d) listing cycles, CBPO staff has updated computer programming and interpolation procedures to reflect the jurisdictions' adopted water quality criteria, designated uses, and criteria attainment assessment procedures. ¦ There are nine different DO criteria, of which only 3 have been used in 303(d) assessments. ¦ Within the 1991-2000 hydrologic years, there are eight three-year assessment periods that must all show attainment. ¦ STAC determined that it is currently not feasible to assess the new 7-day mean, 1-day mean, and instantaneous DO criteria using monitoring data. ¦ CBPO staff are currently focusing their efforts on revising the DO criteria attainment assessment programming and will then turn to the chlorophyll a criteria attainment assessment. Discussion ¦ John Kennedy, VA DEQ, asked how the model calibration is factored into the assessment procedure. Some areas of the model grid have better calibration than others and segments with lower calibration may coincide with segments with compliance questions. How can we ensure the model correctly predicts compliance with DO criteria? 1 ------- o Gary clarified that they are looking at monitoring data from 1991-2000. Criteria assessment procedures are applied to the monitoring data. For scenarios, model output is looked at only in a relative sense. The model calibration run is compared to the scenario and gives a different prediction of dissolved oxygen. Model calibration output is compared to observed data. If the model predicts a 2 mg/L increase in DO, then the monitoring data is given a 2 mg/L increase. o The model output can be used directly for criteria attainment when looking at whether it will be more or less difficult to meet criteria, but it is not the primary decision-making criteria. ¦ Nauth Panday, MDE, said that we need to come up with justification that says the 30- day average will be sufficient to address the 1-day and 7-day mean. Each and every one of the standards must be addressed, and we must show that management will meet the standards. o Lewis Linker said that we have technical standing to do a 30-day mean. The 30-day means provides indication for doing a 7-day mean, o John Kennedy added that we cannot have impairments for standards that we are not currently addressing, such as the 7-day and 1-day mean, o Gary pointed out that we have scenario-derived data for the 30-day mean but can use the model to evaluate the other criteria. The model results suggest that the 1-day and instantaneous means are easier to attain than the 30-day criteria. Using the scenario data and direct model output, we may be able to assess all of the criteria for the TMDL. ¦ Nauth Panday pointed out that Maryland was not mentioned under chlorophyll a, and that if the EPA is doing the TMDL, their standards have to be incorporated into the TMDL as well. ¦ Under the 'Decisions Requested' section of Attachment A, the second bullet should read "57,000 cell Bay water quality/sediment transport model." ACTION: Nauth Panday will send Gary Shenk documentation regarding how they look at chlorophyll a attainment. ACTION: Jennifer Sincock and Rich Batiuk will talk to EPA Headquarters about their position on the three criteria: open-water 30-day mean, deep-water 30-day mean, and deep-channel instantaneous criteria. DECISION: Reevaluation Technical Workgroup members agreed to use the exact same revised criteria assessment procedures developed by the Criteria Assessment Procedures Workgroup and approved by the Water Quality Steering Committee for publication by EPA in the 2008 bay criteria addendum and adoption by the jurisdictions into their state water quality standards for all model-simulated assessments of dissolved oxygen and chlorophyll a criteria attainment during development of the Bay TMDL. DECISION: Reevaluation Technical Workgroup members agreed to use the proposed model scenario-modified monitoring data method, revised to reflect the latest partner 2 ------- agreed to criteria attainment assessment procedures and the 57,000 cell Bay water quality/sediment transport model, to assess attainment of the open-water 30-day mean, deep-water 30-day mean, and deep-channel instantaneous criteria during development of the Bay TMDL. DECISION: Reevaluation Technical Workgroup members agreed to use the direct model scenario output to estimate attainability of dissolved oxygen criteria not listed above in Decision 2. DECISION: Reevaluation Technical Workgroup members approved allowing Chesapeake Bay Program staff to move forward with development of the chlorophyll a criteria attainment assessment programming as presented, including Maryland's assessment procedures. DECISION: The Reevaluation Technical Workgroup will revisit the fourth requested decision on Attachment A, which calls for using the open-water 30-day mean, deep-water 30-day mean, and deep-channel instantaneous criteria as the primary basis for deciding whether a specific scenario achieves Bay criteria, when more information is available. ACTION: The daily loads methodology follow-up discussion will occur on the next conference call on July 17th, after which Jennifer Sincock will have received feedback from EPA Headquarters and Tetra Tech will have prepared a position paper. Next Reevaluation Technical Workgroup Conference Call Thursday, July 17, 2008 10:00 to 11:30 AM Topic: Allocation of CAFO Loads and Model Representation of These Loads: Hank Zygmunt, Lewis Linker, Jeff Sweeney Topic: Agreement on a Daily Loads Methodology Participants Jennifer Sincock EPA Region 3 Rich Batiuk EPA/CBPO Sara Parr CRC/CBPO Gary Shenk EPA/CBPO Jeff Sweeney UMD/CBPO Lewis Linker EPA/CBPO Jeni Keisman UMCES/CBPO Russ Perkinson VADCR John Kennedy VADEQ Hassan Mirsajadi DEDNREC Monir Chowdhury DDOE Bill Brown PA DEP sincock.i ennifer@epa. gov batiuk.richard@epa.gov sparr@chesapeakebav.net gshenk@chesapeakebav.net i sweenev@chesapeakebav.net llinker@chesapeakebav.net ikeisman@chesapeakebav.net russ.perkinson@dcr.virginia.gov imkennedv@deq.virginia.gov Hassan.mirsaiadi@state.de.us monir.chowdhury@dc.gov willbrown@state.pa.us 3 ------- Ed Reilly Tom Thornton Nauth Panday Andrew Parker NY DEC MDE MDE Tetra Tech exreilly@gw.dec.state.ny.us tthornton@mde. state.md.us npandav@mde.state.md.us Andrew. parker@tetratech-ffx. com 4 ------- |