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<br /> <br />~AHA DISTRICT, CORPS OF ENGINEERS .. <br />~2 U,S. POST OFFICe: AND COURTHOUSE 'W <br />OMAHA, NEBRASKA 68102-4978 <br /> <br />AE:PL Y TO <br />^TTENTlON OF <br /> <br />January 13, 1987 <br /> <br /> <br />Planning Division <br /> <br />Mr. J. William McDonald, Director <br />Colorado Water Conservation Board <br />721 Centennial Building <br />1313 Sherman Street <br />Denver, Colorado 80203 <br /> <br />Dear Mr. McDonald: <br /> <br />We have completed our reanalysis of the water supply storage potential <br />at Bear Creek and Chatfield Lakes. Our reanalysis was brought about by <br />the development of new hydrologic criteria contained in the Interagency <br />Hydromet Study-Number 55. As you know, this study caused us to reconsider <br />whether we could reallocate flood control stor~ge to water supply storage <br />as we had indicated to you in late 1984. <br /> <br />Our reanalysis considered freeboard at both dams under the new criteria, <br />with water supply storage, and while maintaining a flood flow target of <br />5,000 cubic feet per second at the Henderson gage. Through this reanalysis, <br />we have determined that storage at both reservoirs can be safely reallocated <br />to water supply at approximately the same levels previously indicated <br />to you; i.e., 18,400 acre-feet at Bear Creek and 22,700 acre-feet at Chat- <br />field. The only major impact of this is that there would be water in <br />the flood control zone at Bear {reek more frequently than occurs at present. <br />To mitigate this, \'Ie feel that the proj.ect must be operated in such a <br />manner that the water supply zone is '/3cant as much as possible during <br />times of expected high flood inflows. <br /> <br />The major hydrological constraints on water supply storage in the <br />two reservoirs have now been identified and quantified. Two other major <br />constraints exist. These are the impacts on recre~tion facilities anJ <br />enlfirOtllllentai effects. These two c;;nstraints wiil be addressed by the <br />water storage sponsor. <br /> <br />Re~reation facilities at both reservoirs are heavily used. Changes <br />in the quality of recreation are likely to 6e met wich conside~able oppo- <br />sition -- this is particularly true at Chatfield. A water storage operating <br />plan should, therefore, be developed and coordinated to identify levels <br />of storage and recreation impacts. The costs of replacing or relocating <br />recreation facilities will be included in the water storaoe contrac: and <br />will be borne by the water storage sponsor. - <br />