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't I I CWCB Construction Bill 99-173 with Section 16 which includes the language"... the Board is hereby authorized to expend up to seventy-five thousand dollars ($75,000) to corporate with NWS and Corps, and hther state agencies and agencies of local governments for a technical evaluation and public ieview of the probable maximum precipitation and probable maximum I flood values associatedyvith the Cherry Creek Reservoir." I I I F or the July 21, 1999 formal technical meeting, the CWCB and the Corps co-hosted a discussion with the National Weatlier Service (NWS) regarding their PMP study for the Cherry Creek basin. The purpose of the tecl~nical discussion was for the NWS to address the PMP methodologies, analyses, assumptions, ~nd results, and to clarify issues that have surfaced at the public meetings and other discussions. rrhe July 21 st meeting, which was a round table format, was chaired. by Bill Miller, the Corps' Broject Manager for the Cherry Creek Dam Safety Study. I THE JULY 21, 1999 TECHNICAL DISCUSSION I I I As mentioned previousl~, the purpose of the July 21 st technical discussion was for the: NWS to address the Cherry Cre~k Dam Safety issues for the PMP and to clarify questions and concerns which have surfaced at recent public meetings and discussion groups. The technical discussion I group was made up of professionals who have a working knowledge of the PMP process, procedures and best prqfessional judgements that must be considered for a PMP analysis (see attached group list). : I The NWS, in cooperation with the Corps, conducted the July 21 st PMP presentations. The NWS presented the following technical discussions: I I · NWS Probable Ma~imum Precipitation (PMP) methodologies under NOAA Hydrometeorologicc:U Report No. 52 (HMR 52) and NOAA Hydrometeorological Report No. 55A (HMR 551\); · "Cherry Creek Site Specific PMP Study" by Douglas R. Kluck and Douglas D. Fenn, dated July 13, 1995; and : · "Antecedent Precipit~tion Study Approach," dated July 1997. The Corps' Cherry Creek Dam Safety Study has three major study activities which are the basis I for the determination of:the level of risk that exists 'for the Cherry Creek Dam and Reservoir as the public and governm~nt officials view the system today. These three major study activities are: , · Site Specific PMP study by the NWS; · Probable Maximum flood (PMF) event and it's resultant reservoir inflow hydro graph; and · Reservoir routing p~ocedures and the project operation, which determines reservoir pool levels and the maxim;um discharge capacities for the existing spillway and outlet, works. I It should be understood tpat each one of these major study activities requires a high level of "best professional judgement",: "an expectation of a reasonable degree of correlation for historical and regional conditions" and: "a recognition of climatological and hydrological parameters". I . ,~ , ". j\ II 2