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If the objective is simply to maximize recharge to a given set of recovery wells exclusive <br />of gaining storage credits, then many other locations are possible, so long as the provider <br />can meet other regulatory constraints such as gallons pumped per capita per day. <br />Another regulatory constraint is the need to obtain surface water appropriations. In <br />Arizona, some water rights exist along ephemeral streams based on historic diversion of <br />floodwaters for stock or irrigation. In addition, appropriations have been granted for <br />subflows. The Rillito Recharge Project has shown that new surface water appropriations <br />may be issued, despite claims that basins are overappropriated. However, conflict <br />resolution may be time consuming or costly. <br />CAP Water Recharge <br />Recharge of the central well field is a pressing need in the Tucson basin. In November <br />1995, city of Tucson voters approved the Water Consumer Protection Act, which sets <br />forth certain standards for CAP water, should it be delivered to customers for drinking <br />purposes. The act encourages basin and streambed recharge of CAP water and requires <br />recharge of all groundwater withdrawals from the central well field during a 5 -year <br />period. The city is obligated to pay for its full allocation of 148,420 acre -feet; however, it <br />has only requested 20,000 acre -feet of CAP water for 1995 (SAWARA, 1995). <br />Although the district will not construct the project to recharge stormwater, studies <br />conducted for the Rillito Recharge Project have shown that Rillito Creek may be used to <br />recharge the central well field using some of the city's CAP allocation. With careful <br />consideration of the limited aquifer storage upstream of Swan Road, CAP water could be <br />released directly into the streambed or in- channel or off - channel basins located on lands <br />purchased for the Rillito Project. The remaining questions concerning the potential for <br />landfill contamination near Columbus Road could be resolved with more borings and <br />surveys. Based on existing data, it appears likely that CAP water can be safely recharged <br />in the Swan -to- Alvernon reach. This reach has greater aquifer storage capacity and <br />conveys water more quickly to the central well field than does the upstream reach. <br />High Plains States Groundwater Demonstration Program <br />