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. . . 0913 Arr:! flood control reservoir, to be ef'tective, must. necessar1q'change ~the regimen of the stream cn which it is constructed. The tempcrary,retei1tion of flood,waters necessartq reduces the peak flaws which would otherwise oogur. It is possible that this inherel;lt effect, while mitigating flood. damages, maybe adverse to the diversion opportunities of the more junior apprGlpriators of strelllll flow downstream from the project. The lower the rate at which water impounded in the flGlod cont,rolportion of a reservoir is released, the greater this adverse effect m~ be on water users with junior priorities. ' It has been dellirable in connection with other flood control reservoirs in Colorado that the outlet works be so designed that the rate of, discharge from t1'le flood control pool should be ms,intained as nearq as possible at the ma:xim1lm channel capaCity above which !'lood damages cOllDllence in the area to be protected belaw the reservoir. In the case of the proposeTrinidad Reservoir Project, it would thus appear, in vi_ of the concern which Will un<ioubtedly be expressed by present water users belaw the project, tha~ in connection with the report, a study should be made of the effects on project CGsts and ono downstream water uses, of providing increased out- let discharge capacity to pass neods during periods when the conservation pool might be empty. Tile optimum outlet capacity to be considered would be $;000 cubic feet' per second, according to the report, statement regarding bsnk caving. With regard to Appendix D, the irrigation report by the Bureau of Reclamation, it is stated in paragraph 42, on page 1$, that the regulation of existing and supplemental supplies of water for irrigation use requires a conservation capacity of 55,000 acre feet in the proposed Trinidad Reservoir. Also, that the maximum utilization of this capacit;, can be, achieved by operation,in accordance with five basic conditions. Condition Oa" proposes the transfer of the storage decree of the Model Land and Irrigation ComplUlY for 20,000 'acre feet annually from the present site to the site of the proposed Trinidad Reservoir. It is my understanding 'that such a transfer m~ be made under the Colorado statutes. However, the transfer must,in effect, be consented to by all water users who might be affected by the transfer. There is no statement in the report that the Model Land and Irrigation Company is presently willing to attempt to make the transfer, nor is any reference presented with respect to possible tentative inquiries among interested water users as to the possible consumma- tion of such a transfer. Condition'UbUproposes the storing in the Trinidad Reservoir of flood !'laws originating,on the Purgatoire River above the damsite which would otherwise spill trom John Martin Reservoir. For the present purposes of the report, it is suggested that a language revision be made to indicate that such storage wi:1.1 be made only during periods when water is actually spilling from the conservation poelin John Martin Reservoir., Condition "c" proposes storage in Trinidad Reservoir of the winter flaws of the Purgatoire River historically diverted for winter irrigation of project lands; anli partial regulatiOn of summer flows historically diverted in order to more nearly meet the seasonal distribution of irriga- tion requirements, such partial regulation not to increase the total APPENDIX G Exhibit No. 12 Page 2 of 4 '''''m':;..",,,,, " - 0<~_' .~'" .' , c};;,.(<,~d' :;i!~'- '-"" , .