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delivery, up to 1,200 acre- feet per month (1.48 mcm) will be delivered for Tijuana, Baja California in 2005. To further improve control ofthe deliveries of water from Parker Dam, Senator Wash Rese:rvoir and . the reservoirs behind Imperial Dam and Laguna Dam will continue to be operated at lower elevations . during periods of potential rain storms to capture flows in excess of water demand at Imperial Dam. Improvements to the river routing software used to schedule: the releases from Parker Dam have also reduced the uncertainty in estimating the flows arriving at Imperial Dam, further helping to reduce non-storable flows arriving at Imperial Dam. As mentioned previously, other storage options are also being investigated which willi mprove t he control of deliveries below Parker Dam when constructed. Measures that are being taken to ensure that the salinity differential requirements at the NlB will be met include 1) reducing drainage pumping in the South Gila Valley in areas with more than adequate depths to groundwater when necessary; 2) retuming some drainage flows from the Yuma Mesa Conduit to the Yuma Valley Drainage System and then to the boundary pumping plant at the sm w'ith Mexico; 3) ensuring that no drainage water from the Main Outlet Drain Extension will be spilled to the Colorado River; and 4) reducing drainage pumping from the Yuma Mesa W'ell Field when necessary near areas with acceptable depths to groundwater (generally wells YM: 10-13). These reductions are generally made during periods when Mexico's water order is the lowest- normally September, October, and November. In December of2003, several drainage wells in the Yuma area were shut off to ensure that the salinity differential would not exceed the maximum allowed. As stated in Minute 242, the maximum allowable differential is 145 ppm by the United States' measurement or count and l51 ppm by the Mexican count. The final salinity differential in 2003 was 136 ppm by the United States' count and 147 ppm by the Mexican count. Mexico has identified four critical months, October through January, regarding the quality of water delivered at the SlB. As a matter of comity, the United States has agreed to reduce the salinity of water delivered at SlB. To accomplish the reduction in salinity, the United States constructed a diversion channel to bypass up to 8,000 af of Yuma Valley drainage water during the four critical months. This water will be replaced by better quality water from the Minute 242 well field to reduce the salinity at SlB. Cunently, the facilities required to monitor the flow and salinity of water delivered to SlB have not been installed or calibrated. Work on these facilities at SlB will take place in water year 2005. 22