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City of Rifle Water Conservation Plan Final Report -July 2008 o Ruedi Reservoir Water. The City currently has a 20-year lease (through 2019) with the U.S. Bureau of Reclamation for 350 ac-ft/yr of Ruedi water as an augmentation supply. The City pays approximately $49/ac-ft toward reservoir construction reimbursement, plus about $4/ac-ft for 0&M. A 10% transit loss applies to this supply, reducing its effective value to 315 ac-ft/yr. • Water accounting calculations in the City's 1986 augmentation plan assume that irrigation water use is highly "efficient." That is, 90% of all water diverted for outdoor use is consumed with 10% being return flow (i.e. excess water that makes it back to the river). This assumption's legal implication is that reducing irrigation water deliveries in the City produces a very direct, pronounced reduction in officially calculated out-of priority water diversions. Therefore, reducing irrigation water deliveries can have a marked impact on reducing the City's need to acquire additional firm municipal water supplies in the future. • The City has acquired additional senior historic irrigation water rights, which it could convert in the future to depletion credits through another augmentation plan. This could result in another approximately 124 ac-ft/year of depletion credits to cover out- of priority diversions for municipal use. Return flow obligations of 5 to 10 ac-ft/yr might be expected from dry-up of the associated irrigation rights. • In contrast to Front Range water providers, the City's water utility, like many on the Western Slope, does not currently face exceptional raw water supplylwater rights costs. The implication for water conservation is that reducing overall annual water consumption does not, in and of itself, provide large economic benefits at this time, or in the near future. In summary, based on the current municipal-use water rights portfolio for its potable system, the City has approximately 10.1 cfs of reliable direct diversion rights, plus about 1,015 ac-ftlyr in existing/potential augmentation supplies, all on the Colorado River. Potable System Limitations Key existing City of Rifle potable water system limitations are: • Water production capacity barely exceeds current peak demands. Peak day demands of about 4 mgd are approaching the dry-year capacity of about 4.65 mgd. Because of the GMWTP's sedimentation process design, true "firm" production capacity is effectively zero. • The GMWTP, the City's main production facility, suffers from aging equipment throughout, a lack of process redundancy that inhibits effective maintenance and increases the frequency of water service curtailments, an unreliable clarification process design, obsolete and undersized filtration technology, a lack of on-site chorine contacting, and a site whose location and size do not fit with either the need for significant future capacity expansion or with local land use patterns. • Replacing or upgrading the GMWTP with ahigher-capacity, higher-reliability, state- of the-art facility will cost the City tens of millions of dollars in the near future. • The BCWTP does not have a water supply that is reliable in a dry year. Therefore, the only reliable water supply in a dry year to service areas south of the Colorado River is a single transmission line crossing the Colorado River. • As upstream trans-mountain (and other) diversions occur out of the Colorado River basin, the river will continue to become more saline, reducing its quality as a potable supply. Winter TDS levels regularly reach 700 to 800 mg/L at Rifle and have SGM # 99055A-388 9 Existing Water System Profile