Correspondences Concerning City of Denver's Use of Colorado River Water (2002)

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Ms. Maryanne C. Bach 12/30/99 Page 5 Lawn Irrigation Return Flow. In 1999, Denver Water completed Phase I of its efforts to quantify reusable return flows from the irrigation of lawns within its service area by developing a work plan to guide the activities of Denver Water's staff and consultants for the next five years. The proposed work plan, which is Phase II of the project will be presented to the Board of Water Commissioners for approval in February 2000. If approved, Phase II will be implemented and upon completion in approximately 2005, will provide the basis for an application to the state Water Court for adjudication of the return flows. An additional five years will likely be needed to negotiate a decree with other water users permitting the legal use of these return flows. Once quantified and decreed, the return flows will provide Denver an additional source of water for exchange to its raw water facilities or for delivery to other non - potable uses in the metro area. Downstream Storage. Also as part of the System Refinement portion of the near -term supply strategy, Denver is pursuing storage on the South Platte River downstream of Denver to enhance the yield of its municipal water system. This storage would recapture and regulate Denver's reusable return flow presently relinquished to the river due to the lack of timely upstream exchange potential or demand. After storage, these return flows would be released to the river when upstream exchange potential exists. Additionally, downstream storage will be needed to augment the Nonpotable Reuse Project when there is legally insufficient reusable return flow available to the reuse plant. As Denver pursued the acquisition of suitable storage sites, which are principally mined gravel pits, it encountered several other entities interested in cooperatively developing such sites. Denver is actively discussing this with some of these entities and has completed appraisals, surveys, geotechnical investigations, and environmental evaluations for some of the potential sites. To date, it has completed the acquisition of three of these sites representing potential storage of about 10,000 acre -feet. Denver will continue to pursue additional acquisitions in 2000. Downstream storage is also the cornerstone of the above - mentioned commitment to provide Non - potable Reuse Project water to the Rocky Mountain Arsenal. Effluent Exchange Diligence. The City of Thornton is challenging Denver's use of reusable effluent to perform river exchanges in Case No. 96CW 145, Water Division 1. This is Denver's diligence filing for exchanges to its South Platte River diversion facilities in former Water District 8. Among numerous claims, Thornton contends the effluent does not meet its water quality requirements. Also at issue is the reuse of Williams Fork Reservoir water stored in Dillon Reservoir by exchange and brought to the east slope through the Roberts Tunnel. Trial began October 18, 1999 and is expected to continue well into 2000. The trial is complex, lengthy, expensive, and Denver is vigorously defending its rights to exchange reusable effluent.