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Project Objectives tit The project objective was to determine if a groundwater recharge demonstration project in an agricultural area was a technically and economically viable solution to dwindling water supplies resulting from declining groundwater levels due to long-term irrigation ground- water pumping. The declining water table threatens the irrigation water supply and dramatically increases agricultural production costs. The project demonstrated whether untreated surface water supplies could be used for groundwater recharge and if the existing groundwater wells could be used for surface water injection which would eliminate the need for new groundwater well construction. Project Description The project area is located in southern Idaho within the SWID between the small communities of Murtaugh and Oakley. This is a productive agricultural area irrigated from deep groundwater wells. There are four groundwater aquifers in the study area, including basalt, limestone, rhyolitic, and alluvial formations. The Oakley Fan Area, where the groundwater recharge project is located, was designated a "critical groundwater area.. by the Idaho Department of Water Resources. Subsequently, . further development of groundwater resources stopped in the area. Local irrigators are concerned that if groundwater levels decline to the point where wells could not meet crop water needs with .'reasonable'. pumping requirements, irrigators that hold '.junior'. water rights may have to go out of production. Recharge could be an important means to augment groundwater supplies. Because of the size and complexity of the Oakley Fan groundwater problems, seven different groundwater recharge sites were selected for development. Several recharge sites helped determine (under present irrigation pumping conditions) if surface water ground- \YilterLecbarge is a viable way to prevent further declLne and stabilize or increase groundwater levels in the aquifers recharged. Funding limitations for the demonstration program resulted in phased development of this project. The SWID selected one of the seven sites (site 6) for initial development in Phase I. The site selected required a pumping plant, conveyance and distribution facilities, con- struction of two injection wells, and development of monitoring wells. The monitoring program focused on protecting water quality and assessing the value of the recharge activi ties. Phase II completed site 6 and developed the other six sites. Individualized groundwater recharge sites were located on Cottonwood Creek, Dry Creek, in the Artesian area, and near the west and east ends of Murtaugh Lake. . 2