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r, ~,~, Colonel John N Reese DRAFT 3 ~ ~ Navajo Dam was closed, and Navajo Reservoir began to fill with water from, the ~ San Juan River. Historically, flows in the San Juan River prior to the Navajo ~l Dam were highly variable and ranged from a low of 44 cubic feet per second (cfs) in September 1956 to a high of 19,790 cfs in May 1941 at the U.S. Geological Survey Station 93680000, Shiprock, New Mexico. Conversely, post-Navajo Dam flows in the San Juan River have ranged from a low of 185 cfs in July 1963, while the reservoir was filling, to a high of 9,508 cfs in June 1979. According to the Bureau of Reclamation, since 1963 Navajo Dam has significantly altered flow of the San Juan River by typically storing spring peak flows and releasing water in summer, fall, and winter months resulting in an average decrease in spring peak flows of 45 percent, while approximately doubling winter base flows at the Bluff gauge in Utah. Similar comparisons can be made at the upstream gauges at Shiprock and Farmington, New Mexico. Significant depletions and redistribution of flows of the San Juan River also have occurred as a result of other major water development projects, including Navajo Indian Irrigation Project and the San Juan-Chama Project. None of these three projects have completed section 7 consultation under the Endangered Species Act. The Bureau requested formal consultation with the Service on July 30, 1991, for the operation of the Navajo Dam. These depletions, along with a number of other factors, have resulted in such drastic reductions in the populations of Colorado squawfish and razorback sucker throughout their ranges that the Service has listed these species as endangered and has implemented programs to prevent them from becoming extjnct. The biological opinion issued by Region 6 of the Service on October 25, 1991, for the Animas-La Plata Project found that the proposed development and subsequent depletion of 57,100 acre-feet of the San Juan River's flow would jeopardize the continued existence of the endangered Colorado squawfish and the threatened razorback sucker. The razorback sucker was listed as endangered on October 23, 1991 (56 F.R. 54957). The Bureau worked with the Service through the informal consultation process and stated in the July 30, 1991, memorandum that it would release flows from Navajo Dam to mimic the natural hydrograph and further help recover the endangered fishes. In general, Navajo Dam releases would be reduced in winter to allow for larger releases during the runoff. Another element of the reasonable and prudent alternatives provided in the opinion called for the formulation of a binding agreement, a Memorandum of Understanding, to protect the releases to be made from the Navajo Reservoir to and through the endangered fish habitat of the San Juan River to Lake Powell. The potential effects of the water depletion proposed by the Red Mesa Reservoir Enlargement Project have been analyzed in the context of the ongoing Navajo Dam consultation and those commitments and agreements derived from the Animas-La Plata consultation. Of primary concern is the quantity of water provided to and through the habitat of the endangered Colorado squawfi~h and razorback sucker in the San Juan River. While water from the La Plata River would be diverted to Red Mesa Reservoir only from January through April, the Project could ultimately affect flows throughout the year. The proposed reduction in winter releases from Navajo Reservoir may not be entirely achieved if water is needed downstream to replace that depleted by Red Mesa Reservoir. If less winter water is stored in Navajo Reservoir, less water might be available for release during the runoff and other times of the year.