Annual Operating Plan For Colorado River Reservoirs 2004

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January 7, 2004 23 ' Measures that are being taken to ensure that the salinity differential requirements at NIB will be met include reducing drainage pumping in the South Gila Valley in areas with more than adequate depths to groundwater; returning some drainage flows from the Yuma Mesa Conduit to the Yuma Valley Drainage System and thence to the boundary pumping plant at the Southerly International Boundary with Mexico; ensuring that no drainage water from the MODE will be spilled to the Colorado River; and reducing drainage pumping from the Yuma Mesa Well Field when necessary near areas with acceptable depths to groundwater (generally wells YM 10 -13). Several Yuma Valley Drainage wells that used to discharge to the Southerly International Boundary ' (SIB) have been connected to the Yuma Mesa Conduit. In addition, 6 Yuma County drainage wells constructed in the late 1980's are now discharging to the Yuma Mesa Conduit, when formerly they were operated only during flood or space building years, causing salinity levels at the NIB to increase ' as the quantity of drainage inflow to the Colorado River above NIB increases. At the same time, the quality of water arriving at Imperial Dam improved, even though the amount of water released from ' Parker Dam has been reduced beginning in CY 2000. These issues combined together are currently resulting in a forecasted salinity differential near the maximum allowed under Minute 242. Located at the Yuma Desalting Plant is a research facility known as the Water Quality Improvement ' Center (WQIC). The primary role of the WQIC is to find ways to reduce operating costs of the YDP. To do this, Reclamation personnel who work in the WQIC investigate new technologies and ' processes, and explore improvements in operational and maintenance efficiencies. The WQIC also serves as a key component in Reclamation's Science and Technology program- hosting third party research to enhance the spread of publicly- developed water treatment technology into private ' industry. This program serves Reclamation in two ways: it reduces the overall cost of maintaining the YDP by performing research for paying outside parties pursuing similar interests, and it helps guarantee additional water supplies by supporting the proliferation of water - stretching treatment technology throughout the U.S. In addition, the WQIC serves as the primary water provider to the Yuma Area Office. The facility purifies about one million gallons per day of drainage water delivered either from the MODE, groundwater pumped from an on -site well, or Colorado River ' water. The WQIC will continue to operate during calendar year 2004. Colorado River Channel Aggradation Below Gila River Confluence The 1993 Gila River flood deposited approximately 10 million cubic yards of sediment in the ' Colorado River between its confluence with the Gila River and Morelos Dam. An additional unspecified volume of sediment was deposited in the river channel below Morelos Dam. The aggradation of the channel substantially reduced the river's capability to carry flood flows and to act ' as a drain for groundwater, and has occasionally caused operational problems with the delivery of Treaty water to Mexico at Morelos Dam. ' The Yuma Area Office developed a project proposal to address the aggradation problems in cooperation with local irrigation districts, the IBWC, Native American tribes, local environmental organizations, local governments, and other State and Federal agencies. 7