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r f1 r-, . "'.T~e 1 ands with i n the Project area have been i rri gated since the 1860' s. However, the errat i c nature of the unregu 1 ated Purgatoi re Ri ver flow has not been conducive to effective irrigation. As a result, the need for conservation storage for irrigation was realized and incorporated into Trinidad Project. The Project lands are located in the valley along the Purgatoire River and on uplands north of the valley extending downstream about 25 miles below the city of Trinidad. Except for 1 i mited storage in the off channe 1 Model Reservoi r, (owned by Mode 1 land and Irrigation Company) which served 6,177 acres of the irrigated area prior to completion of the Project, no significant storage or regulation was avai lable for the flows of the Purgatoire River. The Model Reservoir had a 20,000 acre-foot storage decree, but a reservoir survey in 1946 indicated that usable capacity had declined to only 6,200 acre-feet due. to sediment deposition. Except for th is 1 i mited storage, the proj ect area of about 19,700 acres was served by direct flow diversions through eleven (II) different ditches. The Bureau performed hydrologic and economic analyses of the irrigation function of the Project. The results of this study was completed and presented in Appendi x A Water Supp ly and Ut i 1 i zat i on Report of Apri 1 1961, hereafter re- ferred to as the "1961 Study". The 1961 Study proposed that in order to accomp 1 i sh storage, regu 1 at i on, and improvement of the water supp ly for the Project area the fo llowi ng conditions would need to be met: 1. Transfer the 20,000 acre-foot storage decree of the Model Reservoir from the present site to the proposed Trinidad Reservoir. 2. Store in Trinidad Reservoir, in addition to storage under the Model right (transferred Model storage right), any flood flows originating on the Purgatoire River ftbove the damsite which w.ould be otherwise spill from John Martin Reservoir. 3. Store in Trinidad Reservoir under Model right (maximum rate of 700 cubic feet per second and 20,000 acre-foot filling) winter (November through March) flows of the Purgatoire River historically diverted for winter irriga- tion of project lands which are in excess of flows required to meet the lesser of either the historical diversions or the decreed rights of the Ninemile and Highland Canals and 5 cubic feet per second passed through the reservoir for livestock or domestic watering purposes. Useable project computed return flow was to be considered available to meet the downstream rights. 4. Store in Trinidad Reservoir under the Model right (maximum rate of 700 cubic feet per second and 20,000 acre-feet of filling) summer (April through October) flows of the Purgatoire River in excess of immediate require- ments of the Project area and flows requi red to meet the lesser of either the historical diversions or decreed rights of the Ninemile and Highland Canals. Useable 2