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<br />- 3- <br /> <br />Chanl!.inl!. Chatfield Reservoir Criteria <br />The Corps has presented some options to get 20,600 AF of storage space reallocated and they are <br />highlighted below. <br /> <br />1. Non structural - Conduct a Site-Specific Antecedent Flood Study: Mr. Doan showed us <br />that routing a 40% PMF instead of a SO% PMF would allow for the five feet of freeboard. <br />There was discussion of the Cherry Creek Site Specific PMP Study completed by the CWCB <br />and Applied Weather Associates. This study had numbers for the precipitation numbers in <br />the PMP that drive the PMF that were 2S% lower when using regional storms over the storms <br />in the Hydro-Meteorological Reports (HMRs). <br />. A site-specific antecedent flood study at Cherry Creek Reservoir completed by the <br />National Weather Service was 38%. <br />. The PMF study for Chatfield was done in the early 1970s. HMRs are used for dam safety <br />and HMR 44 was done exclusively for Chatfield. <br />. The Corps will start discussions with the National Weather Service and present to the <br />group an estimated cost and timetable to conduct a site-specific "Antecedent Flood <br />Study". <br /> <br />2. Non structural improvement - increase maximum outlet works release criteria from <br />5,000 CFS to 7,000 CFS. <br />. Fred Rios mentioned that there might be issues with that level of releases at the C-470 <br />bridge. We should consult with the Colorado DOT regarding bridge design capacity. <br />. Bill Doan stated that with the gates fully open the Corps would barely be able to release <br />7,400 CFS. <br />. Most of the bridges are designed for the 100-year discharge, upstream of Bear Creek <br />where 16,000 CFS is the 100-year discharge. <br />. Fred Rios also mentioned that we may want to look at increasing the release ramp up rate <br />from SOO CFS to 700 CFS to see if there is anything gained. <br /> <br />3. Structural Improvements - widen the spillway from 390' to 490' at an estimated cost of <br />$18 million. <br /> <br />4. Structural Improvement - add a 3.5' concrete wave walVparapet wall at an estimated <br />cost of $1.1 million. The wall would be the full length of the reservoir approximately 13,000 <br />feet long. <br /> <br />Anyone of these four changes would yield an additional 20,600 AF of water supply storage space. <br /> <br />Water Users Sub-Committee <br />At the project meeting on May Sth ballots were passed out to vote for a chair for the Water Users <br />Sub-committee. <br />. There were three logical choices: Rick McCloud- Centennial W &S, Marc Waage - Denver <br />Water, and Paul Flack - State Parks. Rick McCloud won by a vote of 12-2 over Marc Waage <br />and will chair this group. <br />. Larry Lang will be co-chair. <br />. The plan is to hold meetings this summer through early fall and invite all 16 water users with <br />water rights and any viable interest in Chatfield Reservoir storage space. <br /> <br />Flood Protection - Water Project Planning and Finance - Stream and Lake Protection <br />Water Supply Protection - Conservation Planning <br />