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Plan for Controlling Salt Inflow The Definite Plan Report was completed in 1978 recommending constructing a system of wells into the brine aquifer adjacent to known brine inflow areas. These wells would be pumped to lower the freshwater-brine interface below the level of the river channel (see figure 3). A pumping rate of 5 cfs was estimated necessary to control 90 percent (180,000 tons) of the brine inflow. The collected brine would be disposed of in an evaporation pond located in Dry Creek Basin. In March 1980, a verification program was begun to evaluate the proposed plan. Pump testing and monitoring was initiated using 18 brine production wells, 100 monitoring wells, and a temporary brine holding pond. Tne brine production wells are located on both sides of the river and vary in depth from 50 to 300 feet. These wells are grouped into an upper and lower well field, located adjacent to brine inflow areas. The monitoring system consists of 93 piezometers varying in depth from 50 to 225 feet deep and 63 water table observation wells. Because of the limited capacity of the brine holding pond, the production wells were pumped on a rotating basis in order to evaluate the efficiency of each. The testing program has shown this plan to be a highly effective method of controlling brine inflow to the river. In the area of wells being pumped, the freshwater-brine interface was lowered and the inflow of brine to the river was greatly reduced, and in some locations totally stopped. We found that approximately 60 percent of the brine inflow can be eliminated by pumping selected wells at a rate of 1,2 cfs (see figure 4). During the testing program, an additional area of brine inflow was iuentified between ttle upper and lower well fields. To control this inflow, 5 new brine pruduction wells and 23 water table observation wells "'1-570 7