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<br />January 7, 2004 21 <br />rejected water caused by rain in January, February, March and April. To further improve control <br />of the deliveries of water from Parker Dam, Senator Wash will be operated at a lower elevation <br />(below the minimum power pool) to capture additional excess flows at Imperial Dam. <br />Improvements to the river routing software used to schedule the releases from Parker Dam may also <br />reduce the uncertainty in the flows arriving at Imperial Dam. Other storage options are also being <br />investigated, primarily the proposed construction of reservoir storage near the All American Canal. <br /> <br />Yuma Desalting Plant <br /> <br /> <br />Laguna Reservoir is a regulating storage facility located approximately 5 river miles downstream of <br />Imperial Dam. Operational objectives are similar to those for Senator Wash Reservoir. The storage <br />capability of Laguna Reservoir has diminished from about 1,500 acre-feet to about 400 acre-feet due <br />to sediment accumulation and vegetation growth. Sediment accumulation in the reservoir has <br />occurred primarily due to flood releases that occurred in 1983 and 1984, and flood control or space <br />building releases that occurred between 1985 and 1988 and from 1997 through 1999. Dredging of <br />the Laguna Reservoir to increase its storage capacity is scheduled to begin around CY 2005. <br />Maintenance dredging of the Laguna Desilting Basin, located above Laguna Dam, was started <br />during CY2003 and will continue into CY 2004. It is also planned to lengthen the desilting basin at <br />Laguna by about 1,500 feet in CY 2004. <br /> <br />Imperial Dam <br /> <br />Imperial Dam is the last diversion dam on the Colorado River for United "States water users. From <br />the head works at Imperial Dam, the diversions of flows for American water users and Mexico occur <br />into the All American Canal on the California side, and into the Gila Gravity Main Canal on the <br />Arizona side of the dam. These diversions supply all the irrigation districts in the Yuma area, in <br />Wellton-Mohawk, in the Imperial and Coachella Valleys, and through Pilot Knob to the Northerly <br />International Boundary (NIB) to the Mexicali Valley in Mexico. The diversions also supply much <br />of the domestic and industrial water needs in the Yuma area. In CY 2002, approximately 6.141 maf <br />(7.574 mcm) arrived at Imperial Dam; approximately 5.806 maf(7.161 mcm) is estimated to arrive <br />at Imperial Dam in CY 2003. <br /> <br />The Yuma Desalting Plant (YDP) was not operated in CY 2003 and is being maintained in a ready <br />reserve status. In calendar year 2002, the amount ofwater discharged through the Main Outlet Drain <br />(bypass flows) was 119,410 acre-feet at an approximate concentration of total dissolved solids <br />(TDS) of 2800 ppm. The U.S. recognizes that it has an obligation to replace, as appropriate, the <br />bypass flows. Reclamation is preparing a report for Congress that explofes options for replacement <br />of the bypass flows from Wellton-Mohawk, including options that would not require operation ofthe <br />Yuma Desalting Plant. Existing data suggests that operation of the YDP would negatively affect the <br />Cienega de Santa Clara, a wetland of approximately 14,000 acres that is within a Biosphere Reserve <br />in the Republic of Mexico. Reclamation's Yuma Area Office has initiated an environmental <br />planning effort that will determine the extent of the effects. <br /> <br />A short section of the Main Outlet Drain Extension (MODE) near the confluence with the Gila River <br />was damaged during the 1993 Gila River flood and still needs to be repaired. However, seepage <br />