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Castle Pines Metropolitan District Agenda Item 29b <br /> May 9,2014(Updated May 23,2014) <br /> Page 4 of 7 <br /> SOUTH PLATTE BASINS. WITH THE COMPLETION OF ALL METRO BASIN IPPS,THE M&I AND SSI GAP <br /> IS EXPECTED TO BE REDUCED BY 140,000 AF PER YEAR. THE REALLOCATION IS EXPECTED TO <br /> PROVIDE AN AVERAGE YEAR YIELD OF 8,539 AF OF NEW WATER SUPPLY. <br /> SEVERAL CONCEPTS WERE INITIALLY DEVELOPED AND SCREENED USING THE CORP'S PLANNING <br /> PROCESS. FOR CONSISTENT COMPARISON PURPOSES,EACH ALTERNATIVE WAS DESIGNED TO PROVIDE <br /> THE SAME AVERAGE YEAR YIELD OF A FULL REALLOCATION. DURING THE CORPS' SCREENING <br /> PROCESS,MANY ALTERNATIVES WERE ELIMINATED FROM FURTHER EVALUATION, WHILE THE FOUR <br /> ALTERNATIVES BELOW WERE IDENTIFIED FOR FINAL CONSIDERATION. <br /> ALTERNATIVE 1—NO CHATFIELD REALLOCATION,NEW RESERVOIR,NEW GRAVEL PIT STORAGE: <br /> WITHOUT CHANGES TO CHATFIELD'S OPERATIONS, WATER PROVIDERS ABOVE CHATFIELD WOULD <br /> SEEK TO CONSTRUCT PENLEY RESERVOIR, AND WATER PROVIDERS BELOW CHATFIELD WOULD SEEK <br /> TO DEVELOP GRAVEL PIT STORAGE TO MAKE UP THE WATER YIELD A REALLOCATED CHATFIELD <br /> WOULD PROVIDE. THE COST OF THIS ALTERNATIVE IS$283.4 MILLION. <br /> ALTERNATIVE 2-NO CHATFIELD REALLOCATION,NON-TRIBUTARY GROUNDWATER WELLS,NEW <br /> GRAVEL PIT STORAGE:THE LEAST-COST ALTERNATIVE TO REALLOCATING CHATFIELD, WOULD BE <br /> FOR WATER PROVIDERS ABOVE CHATFIELD TO RELY ON MORE NON-TRIBUTARY GROUNDWATER <br /> WELLS AND WATER PROVIDERS BELOW CHATFIELD DEVELOP GRAVEL PIT STORAGE.NON-TRIBUTARY <br /> GROUNDWATER IS CONSIDERED A NON-RENEWABLE WATER SUPPLY AND THUS NOT A PERMANENT <br /> WATER SUPPLY SOLUTION. THE COST OF THIS ALTERNATIVE IS$186.1 MILLION. <br /> ALTERNATIVE 3-MINIMUM CHATFIELD REALLOCATION(7,700 AF):REALLOCATION OF STORAGE <br /> LESS THAN 7,700 AF WAS CONSIDERED BY THE WATER PROVIDERS TO PROVIDE TOO LITTLE WATER <br /> SUPPLY BENEFITS FOR THE COST INVOLVED. THIS ALTERNATIVE WOULD PROVIDE AN AVERAGE YEAR <br /> YIELD OF LESS THAN 8,539 AF,WITH THE SHORTFALL BE MADE UP BY DEVELOPING ADDITIONAL <br /> WATER SOURCES OF NON-TRIBUTARY GROUNDWATER AND GRAVEL PITS. THE COST OF THIS <br /> ALTERNATIVE IS $1 80.2 MILLION. <br /> SELECTED ALTERNATIVE 4-MAXIMUM CHATFIELD REALLOCATION(20,600 AF):THE SELECTED <br /> ALTERNATIVE RECOMMENDED IN THE FINAL FR/EIS WILL PROVIDE 20,600 AF OF STORAGE IN <br /> CHATFIELD BETWEEN THE ELEVATIONS 5432 AND 5444 MSL FOR M&I WATER SUPPLY AND OTHER <br /> PURPOSES INCLUDING AGRICULTURE,ENVIRONMENTAL RESTORATION,AND RECREATION AND FISHERY <br /> HABITAT PROTECTION AND ENHANCEMENT. THE STORAGE WILL BE PROVIDED THROUGH A <br /> REALLOCATION FROM THE EXCLUSIVE FLOOD CONTROL POOL TO A JOINT CONSERVATION/FLOOD <br /> CONTROL POOL. TO MITIGATE FOR THE INUNDATION OF RECREATION AND ENVIRONMENTAL <br /> RESOURCES,THIS ALTERNATIVE INCLUDES RELOCATION AND MODIFICATIONS OF EXISTING <br /> RECREATION FACILITIES AND COMPENSATORY ENVIRONMENTAL MITIGATION FEATURES WITH <br /> MONITORING AND ADAPTIVE MANAGEMENT. IMPLEMENTATION OF THE POOL RISE AND USE OF THE <br /> REALLOCATED STORAGE SPACE WILL OCCUR IN INCREMENTS AS THE RECREATION MODIFICATIONS <br /> AND PORTIONS OF THE ENVIRONMENTAL MITIGATION FEATURES ARE COMPLETED. <br /> THE FR/EIS RECOMMENDS THIS ALTERNATIVE BECAUSE IT MAXIMIZES THE NATIONAL ECONOMIC <br /> DEVELOPMENT(NED)COST, IS THE LEAST COST ALTERNATIVE,AND THE LOCALLY-PREFERRED PLAN. <br /> THIS ALTERNATIVE MEETS ALL FEDERAL NED GOALS,CORPS PLANNING GOALS,AND <br /> ENVIRONMENTAL OPERATING PRINCIPALS.NEITHER THE PRIMARY FLOOD RISK MANAGEMENT <br /> PURPOSE NOR OTHER AUTHORIZED PURPOSE OF CHATFIELD WILL BE SIGNIFICANTLY AFFECTED BY THE <br /> REALLOCATION. <br /> INCLUDING REOCCURRING COST SUCH AS OPERATION AND MAINTENANCE,THE COST OF THIS <br /> ALTERNATIVE IN FY 2013 DOLLARS IS ESTIMATED AT$178.7 MILLION. COSTS TO BE PAID THROUGH <br />