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-73- of water will result in deeper penetration, thus greater and pro- longed leeching of alkaline materials from the soil will result. (5) Increased turbidities. - The Green River carries a heavy silt load during spring run-off, but is normally quite clear by July. Under anticipated operations the Seedskadee Project will contribute silt from irrigation waste waters until the latter part ~f September. The Big Sandy River contributes a large part of the silt carried in the Green River during the summer months. A combination of silt carrying waters from the Big Sandy, anticipated .silt load in irrigation water from the Seedskadee Project, plus a reduction of river flows and the associated diluting effect in the Green River below Fontenelle Dam may contribute materially to the elim- ination of game fish habitat from the mouth of the Big Sandy River downstream. RECOI~IENDAT IONS It is recommended that the trash fish populations in the Green River above the Flaming Gorge impoundment area be depressed to the greatest possible extent. This would necessarily be accomplished by a complete chemical treat= meat program cooperatively initiated by the states of Wyoming and Utah. It is also recommended in view of the fact ,that carp populations have been found by the fisheries management crew in the Green River proper as far upstream as the mouth of the New Fork River, in the New Fork River as far as the mouth of the East Fork River, in all the sloughs. and tributaries included in these drainage sections,. that the chemical treatment be extended to include these areas. Also, this treatment should be extended up the Green River beyond the mouth of the New Fork River to the mouth of Horse Creek. Omitting these upper sections would only result in an accelerated re-infestation of trash fish in the treated areas. The following chart is an itemized cost of treating the section of the Green River proper as described above and the tributaries entering the Green River throughout the proposed area. of treatment. This estimation was pre- pared by Fred W. Jackson, District .Fisheries Biologist. The estimates of toxicant quantities is based on the average water flows during the latter part of September and early October. Present plans call for impoundage to begin in September, 1962. Toxicant applied in the fall of 1962 .would allow time for dissipation. before stocking in the spring of 1963. Timing of toxicant application and dam closure will have to coincide as any delay would result in a pool being formed which would make the cost of treat- ment prohibitive. In the event that the dam is not completed until the spring of 1963, the estimates may be revised to fit spring flows by multiplying the gallons of rotenone and cost .by a factor of four.