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SUMMARY (Continued) Water supply • Under the no-action alternative, some changes would be expected in the surface water supplies in the valley. Upstream developments would continue to deplete the Colorado River, but present irrigation supplies would be protected by water right laws. No significant changes would occur in ground water levels. Canal and lateral improvements under both alternatives A and B would be designed to provide the historical water carrying capacity available. This would in turn permit irrigation districts to divert the same amount of water as in the past; therefore, maximum diversions would remain un- changed. With alternative B, reduced seepage losses and the elimination of administrative wastewater at the end of laterals could increase adminis- trative waste spills from the canals, which would be expected to result in an increase in wash flows during the irrigation season. Ground water levels would be expected to decline near improved canals and laterals, a reduction that would decrease winter flows in washes and drains. Seepage from canals and laterals would be reduced by approximately 39,500 acre-feet with alternative A and approximately 41,100 acre-feet with alternative B. • Water quality Under any of the alternatives, a significant change is not expected in salt loading to the Colorado River from surface sources. On-farm im- provements would continue and salt loading due to seepage from farm ditches and deep percolation from irrigated fields would decline. Implementing alternatives A or B would be expected to decrease the salinity of the Colorado River above the Dolores River by about 138,000 and 143,500 tons annually and about 23 and 24 mg/L, respectively. Fishery and aquatic environment Colorado River Under the no-action alternative and under alternatives A and B, flows in the Colorado River will continue to decrease as the Upper Colo- rado River Basin States develop their share of the Colorado River. These flow changes may affect fish populations, but accurate predictions of these changes are not possible. Local fisherman use may increase slightly as the Grand Valley population grows. Salinity reductions in the river under alternative A or B would have no measurable impact on the existing fishery in the Colorado River down- stream of the Grand Valley Unit. The water possibly gained during the irrigation season and lost during the nonirrigation season would also have no impact on the existing fishery. S-6