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estimated to range from 0 to 60,000 acre-feet of water, with an average of about 13,900 acre- <br />feetper year. Theoretically, the MVIC would be entitled to a maximum delivery of project <br />water of 105,500 acre-feet, if it is assumed that the senior rights of the MVIC would have <br />zero yield (26,300 acres x 4.01 acre-feet per acre). In the San Juan Model, a 65,000 acre-feet <br />storage account in McPhee Reservoir is assumed to be available to supplement MVIC <br />irrigation demands when the direct flow yield is insufficient. This value is based on the <br />original USBR operation studies for the project. <br />With this storage account in McPhee, the MVIC no longer needs to operate its own storage in <br />Groundhog and Narraguinnep reservoirs as it did historically to supplement its irrigation <br />demands. In 1991, MVIC and the Dolores Water Conservancy District (District), the <br />sponsoring agency for the Dolores Project, entered into an agreement which provided for an <br />exchange of up to 2,300 acre-feet of storage from McPhee Reservoir to the upstream <br />Groundhog Reservoir. This exchange water is then released as necessary to protect a <br />continuance of the historical diversions of water rights on the upper Dolores River that are <br />junior to the senior rights of the MVIC. For purposes of the CRDSS San Juan Model, <br />upstream junior water rights that are included in the model are attached to this exchange pool <br />in Groundhog Reservoir to allow diversions that would otherwise be out of priority with <br />respect to the MVIC's senior rights. <br />Narraguinnep Reservoir is an off-channel reservoir filled using diversions through the Lone <br />Pine Lateral. Prior to the construction of the Dolores Project, the reservoir was reportedly <br />drawn down extensively in most years to provide supplemental late season irrigation <br />supplies. Since McPhee Reservoir has been on line, irrigation releases from Narraguinnep <br />Reservoir are less than historical, typically in the range of 5,000 to 7,000 acre-feet per year. <br />Releases from the reservoir are recorded by the division engineer under WDID 320700. It <br />should be noted however, that these releases may also include direct flow water from the <br />Lone Pine Lateral that is diverted through the reservoir and also that some releases are made <br />from a second outlet directly back into the Lone Pine Lateral. <br />The water imported by the MVIC provides the majority of the water used for irrigation in the <br />Montezuma Valley of the McElmo Creek basin, either directly or in the form of irrigation <br />return flows. The return flows generally accrue to the drainages of McElmo Creek (above <br />Cortez), Hartman Draw, Alkali Canyon, Trail Canyon, Mud Creek, Navajo Wash (near <br />Towaoc) and Yellow Jacket Canyon. These return flows are re-diverted by other irrigation <br />structures and have their own decreed water rights in Water District 32. For the San Juan <br />Model, the irrigation return flows from the MVIC system were apportioned to the different <br />sub-drainage basins using topographic contour maps and the general location of the MVIC <br />laterals and irrigated lands, as shown in the Definite Plan Report (DPR) for the Dolores <br />Project. The location of the return flows was determined in relation to other structures <br />included in the San Juan Model. <br />City of Cortez. Historically, the physical facilities of the MVIC system (Main Canal No. 1) <br />were used for the carriage of Dolores River water decreed for municipal purposes by the city <br />of Cortez. The city's water rights are listed in the following table. After the construction of <br />McPhee Reservoir, these diversions are carried through the Dolores Tunnel and are recorded <br />San Juan & Dolores River Basin Information 2-6 <br />