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<br />Cherry Creek PMP Controversy <br /> <br />. The NWS completed a PMP analysis for the Cherry Creek basin above CC dam on behalf <br />of the Corps of Engineers. Study results were published in July 1995. <br /> <br />. The 1995 PMP study has not received an acceptable "peer review" by local/regional <br />experts outside of the federal government. <br /> <br />. NWS published PMP value is 24.7 inches over 72 hours, which results in a peak inflow of <br />524,000 cfs, and a volume of 262,500 acre-feet. These values are considerably higher than <br />those used for the original dam design. <br /> <br />. There have been on-going concerns from Colorado inlterests and local experts regarding the <br />validity and accuracy of the NWS study results. <br /> <br />. Some examples of technical concerns from Colorado experts: <br />1. Why ha4 the NWS been unwilling to hand over technical backup data for peer <br />review? <br />2. Is the PMP storm area and storm centering appropriate for this basin? <br />3. What is the western limit for the application of HMR 52 and how was it derived? <br />4. Are HMR 52 or HMR 55a even appropriate for use in the Cherry Creek basin? <br />5. Have orographic effects been properly accounted for? <br />6. What is an acceptable ratio of PMP rainfall to 100-year rainfall? <br />7. Will the NWS fix the problems found regarding their analysis of the antecedent <br />rainfall conditions? <br /> <br />. The big controversy: The revised PMP and resulting PMF make the Cherry Creek dam <br />inadequate according to federal guidelines. In order to meet dam safety regulations, the <br />Corps has a responsibility to fix the problem. Unfortunately, fixing the problem will <br />adversely affect public and private property in many ways, will cost lO's of millions of <br />dollars using taxpayers money, and may not even be necessary given the true risk <br />associated with such a low probability event. <br /> <br />. The State is interested in developing a reasonable and acceptable PMP value for Cherry <br />Creek that everybody can live with. <br />