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:~. . -,Jt ..::> ..-l -.-\ r " '.- 2 The assessment also failed to present a thorough cost and salinity reduction analysis for each canal segment. The proCedUrE! to extend the analysis based on total seepage from the Government High1ine Ca~a1 may not be valid and EPA believes it is better to locate those sectlons of the canals and laterals with the highest salt return 1~r priority improvement. Such a comparative selection process may substantially reduce the need for extensive construction and still reduce most of the salt load. EPA believes that the environmentally preferred solution is to limit this salinity control plan to selected canal lining and open lateral lining where conditions warrant. Additional emphasis should be provided i. for on-farm improvements and irrigation management. Canal ~i~ing.may prove to be more cost effective in the future as costs due to sa11nlty lncrease, even so it should still be limited to those segments that have the greatest seepage loss and contribute the largest portion of the salt return. EPA sug- gests that the EIS can be prepared on this project at the same time as con- , struction and rronitoring proceeds on a few short segments of canal and lateral 1 ining. Use of Developed Water The Bureau's assessment indicates that 4000 acre-feet annually will not need to be diverted from the Colorado River due to reduced evapora- tion and reduced consumptive losses by phreatophytes. DOE!s this estimate of saved water include seepage losses such as seepage to ground water recharge? Does this calculation include savings of water due to improved irrigation efficiencies? This salvaged water is a relative small percent- age of total phreatophyte losses, what was the basis of this calculation? The assessment does not analyze the eventual use of this developed water. Additional irrigation use of this water could increase salt load- ing from further increases in irrigation return flows as well as seepage from unlined laterals. The Bureau should develop a pOlicy in coopera- tion with the basin states that defines the eventual use of either salvaged or depleted water from this and future Colorado River Basin Salinity Con- trol Projects. In defining its options for such a policy the Bureau should consider the following: " 1) Total retention of all developed water for instream uses as a means of protecting the public investment. 2) Retaining a percentage of developed water for in-stream uses based on the percentage of the federal capital investment and the local operation, maintenance and replacement costs. 3) In cooperation with the basin states, allow the developed or depleted water from a salinity control project to be added or deleted , "~ . ,. ~ _._-..-..~- I I I I " I