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<br />Metropolitan Water Supply Investigation <br /> <br />MWSI Results <br /> <br />I <br />I <br />I <br />I <br />I <br /> <br />seepage from Barr Lake return flows from irrigation within the Draw and precipitation. <br />The aquifer is currently at or near its storage capacity with discharges to the surface <br />accumulating in Beebe Seep, a surface drainage ruMing north to Milton Reservoir. The <br />aquifer is currently used for supplemental irrigation. Existing use of the aquifer is not <br />precisely known but is estimated to be small compared to the aquifer's storage capacity, <br /> <br />The aquifer has several water quality problems, primarily associated with elevated levels <br />of dissolved manganese and nitrate. These problems reflect historical supply sources to <br />the aquifer and local irrigation practices, The MWSI's initial investigations suggest that <br />more active use of the aquifer coupled with changes in water quality management <br />practices in the Draw could improve the water quality of the aquifer over time. <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />The Companies have an augmentation plan that can utilize the storage potential of the <br />Beebe Draw aquifer for recharge and storage of surface supplies and delivery to irrigation <br />and municipal uses, The Companies envision that the aquifer, combined with Barr Lake, <br />have sufficient storage capacity to meet the Companies' irrigation needs while also <br />providing a major new municipal supply to the metro Denver area. <br /> <br />The MWSI examined the potential use of the Beebe Draw aquifer for storage and <br />subsequent use of water in a conjunctive use arrangement. Background data were <br />reviewed concerning water occurrence in the aquifer. These data suggested a total <br />unsaturated volume in the aquifer of approximately 83,000 acre-feet. This represents the <br />total available storage capacity in the aquifer under current levels of use, <br /> <br />A groundwater flow model was used to simulate the response of the aquifer to recharge <br />under several scenarios. Potential recharge sites were selected on the basis of sufficiently <br />low transmissivity, adequate unsaturated thickness, and location away from Beebe Seep <br />in order to minimize rapid loss of water to the surface, The analysis showed that up to <br />13,000 acre-feet of the aquifer's existing storage capacity could effectively be used for <br />recharge, storage and subsequent withdrawal of water. The balance of the aquifer's <br />storage capacity is located in areas with very high transmissivity, minimal unsaturated <br />thickness, or where recharged water would rapidly emerge at the surface. <br /> <br />It is possible that a program of more intensive use of the aquifer would significantly <br />increase the useful storage capacity of the aquifer for conjunctive use purposes. This <br />would require a more elaborate modeling study addressing the well facility and <br />operational aspects of such a management regime as well as the effects on existing <br />surface irrigation uses and well uses, changes in supply to Milton Reservoir, and aquifer <br />water quality. Such a study was beyond the scope of the MWSL <br /> <br />I <br /> <br />Prepared for the Colorado Water Conservation Board, Colorado Department of Natural Resources by <br />Hvdrosohere Resource Consultants. 1002 Walnut Street, Suite 200, Boulder, CO 80302 <br /> <br />I <br />I <br />I <br />I <br />I <br /> <br />The Beebe Draw aquifer is located relatively far from most groundwater-dependent <br />Denver area providers, Therefore major conveyance facilities would be needed for <br />providers outside of the northeast quadrant of the metro Denver area to make use of this <br />supply in a conjunctive use manner. <br /> <br />52 <br />