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-12- r,lineral water quality Nill be de'1raded on an annual basis as a consel'!uence of municinal, industrial and irrigation uses served by I'/ater from this Project. HO\'/ever, during the irrirJation season, the i\lferarle dissolved solids concentrations of the Gunnison River wi 11 be improved. This seasonal improvement has no significant economic irlOact bet\1een the Pro,iect area and Lake rlead. Therefore, no flow requlation for mineral quality control to protect uses above Lake f'lead is necessary. Be 1 OH Lake f1ead, mi nera 1 qual i ty deteri orati on by the Project \./ill cause dO\1nstream water users to suffer an annual economic loss estimated at $205,000 Hhich clearly indicates the need to incorporate all possible \1ater quality controls in the Project. The large volumes of I'later stored in both Lake Powell and Lake ~lead result in the releases from Lake f1ead bei nq fai rly uni form in mi nera 1 quality reC)ardless of any seasonal or annual fluctuations in flow and quality of the Colorado River and its tributaries above the reservoirs. Therefore, any regula- tion of flow achieved by stora'le of presently avai lable water in the Project reservoi rs vii 11 not change the qual i ty of water di scharqed from Hoover [Jam. In lieu of providinn storaoe in Electric r,1ountain and Cactus Park Reservoi rs for mi nera 1 qual i ty contro 1 of Project-i nduced sa 1 i nity increases below Hoover Dam, other salinity control measures \,/ithin the Project area should be investioated. ^ny such measures found feasible should be included in the Project plan. POLLUTION SOURCE CONTROL Potential salinity control measures may be divided into two cate- nories: \1ater-phase and'salt-phase. The former comprises possibilities for imrrovinn \'/ater ouality by aUrJmentino the \'later supply, \o/hile the latter included nrospects for improvinn \'/ater quality by reducino the salt innut, Several water-nhase control measures described below arrear to have some Merit and should be considered for incorporation into the Project. (1) Phrcatophyte eradication on Project lands and alonn canals and drains could conserve vJater. It should be recognized, hm/ever, that rhreatonhyte eradication nay result in loss of \'Jildlife ha!Jitat and \Jinter protection for cattle and sheep, Further study of this control Measure 1J0uld require consultati on \'/i th the Federa 1 and State Fi sh and Game f\(wnci es. (2) LJI~tter control of the qnantity of Hater anplied throuoh con- servation irrination, the use of irrination and cronpinn