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. - .. - .... .. . .----~-- 0742 The State has acquired sufficient shares in the Catlin Canal to maintain a permanent pool under the above assumptions. During the 25- year period, the average volume of the permanent pool is 10,900 acre- feet (1.3XI07 m3). The initial volume of the pool is 10,000 acre-feet 7 3 (1.2xlO m). The change in water use increased the mean annual surface-water diversion of 18 of the 21 canals in the area having surface-water rights. The remaining three canals are not affected. The total increase in 6 3 surface-water diversion is 1,770 acre-feet (2.2xlO m). Three canals have small decreases in surface-'Water diversion during some months due to the change in water use plan. This decrease primarily happened during the early spring, but also occurred in the late summer. The flow at the State line increased an average of 30 acre-feet u 3 (3.7xlO' m ) per month due to the change plan. This increase in flow is accompanied by a slight increase in the variability of flow at the State line. The difference between ground-water storage change under normal op~ration simulation and the simulation with the cllange in use is insignifican t. The overall benefit to the water users in the basin is due to several factors. The most significant factor is a decrease in the charge in evaporation losses from the nonpermanent pool in John ~lartin Reservoir because of the permanent pool. A less significant factor is the change in timing of return flows from water that had ,been histor- ically applied, but was not transferred. The 2.5-percent river loss charge also adds some water to the system. 24 ...1