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~ Yl- \\~1 LD' ~y''Y' Towns and communities in the study area include Farmington at the confluence with the Animas; and Bloomfield, Blanco, and Archuleta upstream and Fruitland and Shiprock downstream from Farmington. Energy development, agriculture, and tourism and recreation are important industries in the area. In particular, agriculture and recreation are closelv related to Navaio Reservoir and its operation and to flow patterns in the San Juan River. The frontispiece map shows the general project area and the tigure in Attachment A provides a detailed view of the river corridor; the river is demarcated with river mile designations, starting with River Mile 0 at Lake Powell and ending at River Mile 225 at Navajo Dam (these River Mile locations will be referred to throughout the text). The San Juan is similar to other rivers in the upper Colorado River Basin with large flows during spring snowmelt followed by low base flows; however, summer and fall spike flows occur due to thunderstontl_ ':.v~l1.!?Eo a greater degree than in other rivers, Following Navajo Dam construCtion, spring peaks were reduced near y In a and ase flows increased (Bliesner and Lamarra, 2000). In general, upper reaches of the river are cobble-dominated and lower reaches presently sand-dominated; lower reaches are canyon bound, Summer water temperatures have been lowered in the upper reach ofthe river due to Navajo Dam releases, Sediment inflow to the river is significant during summer and fall thunderstorms-there is historical evidence that this was much greater around the turn of the century, when there was rapid erosion of the watershed due to overgrazing or other factors. In the 20m century there was also a large invasion of nonnative vegetation to the river's riparian area. Overall, the combination of accelerated erosion in the watershed, invasion of nonnative plants, and regulation of flow by Navajo Dam has probably created a quite different river environment than occurred 150 years ago. PROJECT DESCRIPTION The twofold purpose of the proposed action is to (I) develop operating criteria for Navajo Dam and Reservoir in order to create and maintain habitat and a healthy biological community in the San Juan River to conserve populations and designated critical habitat of the Colorado pikeminnow and razorback sucker, and (2) maintain the authorized purposes of the Navajo Unit. Reclamation will implement the flow recommendations for the San Juan River (Holden, 1999) by modifying the operations decision criteria of Navajo Dam to provide sufficient releases of water at times, quantities and durations necessary to protect endangered fish and their designated critical habitat while maintaining the authorized purposes of the Navajo Unit. This proposed plan is designed to mimic a natural hydrograph downstream from the confluence of the Animas River. The SJRBRIP uses an adaptive management process that involves annual monitoring and continued research, so the flow recommendations may be refined in response to new information. The Service will periodically review operations to determine if the flow recommendations are being met. 6 00682