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SUMMARY OF CONFERENCE CALL ON WATER QUALITY ANALYSIS CHATFIELD REALLOCATION PROJECT SEPTEMBER 29,2005 PARTICIPANTS: Tetra-Tech: Gary Orendel, Andrew Parker Chatfield Watershed Authority (CW A; Cooperating Agency): Russ Clayshulte, Kevin Urie (Co-Chair) eweB Water Users Consortium (Local Cost-Sharing Sponsor): Rick McLoud Colorado State Parks (Cooperating Agency): Brad Buckner, Jim Smith Corps of Engineers, Omaha: Marty TimmeIWilke, Dave Jensen, Bob Nebel, Betty Peake SUMMARY OF DISCUSSION: Marty Timmerwilke summarized the strategy proposed for the WQ analysis (summarized in the attached memo distributed prior to the meeting). Marty indicated that the proposal attempts to take into consideration the funding situation, time constraints, NEP A requirements, and addressing all the issues raised during the scoping process. A. Metals analysis would involve deternlining the increase in the anoxic water/lake bottom interface to predict the internal metals loading from the lake bottom at an estimated cost of $] 2,000. B-]. Nutrients will be analyzed in a stepwise approach. Building on the metals analysis, flux rates for phosphorus and nitrogen (from the anoxic bottom, decaying inundated vegetation, etc.) will be determined, potential for algal blooms inferred, and assumptions made about dissolved oxygen (DO). The estimated cost of step 1 is $3,000. B-2. If the results of step I detcrmine that reallocation may result in a significant water quality (WQ) impact for nutrients and/or DO, the LAKE2K model will be configured and calibrated using existing data, then Tetra-Tech will run the model in a Monte Carlo simulation to evaluate nutrients, DO, and algae over a range of sediment oxygen demand (SOD) loading conditions to bracket possible influences. Increases in volume and increased anoxic bottom volume are considered, but not operations. The estimated cost of step 2 is $50,000-$60,000. C. Bacteria can not be adequately analyzed with a model. An analysis will be conducted that focuses on the beach area, taking into account the potential for increased bird use. The estimated cost is $8,000. The consensus was that the proposal's approach was logical and cost-effective. Rick McLoud observed that the total estimated cost of WQ analyses other than LAKE2K will be covered by the amount currently budgeted for the EIS WQ analysis task. The approach also involves the group members in the decision-making process. Group members will be provided with the results of the metals analysis and step I of the nutrient analysis and will provide input on whether the LAKE2K model is warranted. In addition, group members will also be consulted with regarding what value of a parameter would be considered critical. Brad Buckner stated that WQ impacts to the fishery is a major concern. Gary Orendel will invite a fisheries biologist from CDOW to join the WQ working group and review the memo, as fisheries impacts are important.