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<br />02114/96 10: 06 <br /> <br />tt303 245 6933 <br /> <br />FISH & WILDLIFE ~~~ ewes <br /> <br />1aI005 <br /> <br />to provide the gradual ascending and descending limbs of the spring peaks. <br />The water from Navajo Reservoir storage is still available 96 percent of the <br />water years to provide the same shape, timing, and frequency, assuming a low <br />winter flow of approximately 300 efs. <br /> <br />Ongoing research is an important feature of the reasonable and prudent <br />alternative. It was sufficient new information from research conducted as a <br />result of the 1979 biological opinion that led to the reinitiation of <br />section 7 consultation for the Project in 1989. It is the implementation of <br />research which will prOVide the Service with further information about the <br />biological needs of the fish specific to the San Juan River Basin and how <br />these needs can best be met. The future development of water in the San Juan <br />River Basin, including the proposed remaining depletions of the Project, will <br />be highly dependent on the outcome of the biological studies which are <br />required as part of this reasonable and prudent alternative, In making future <br />decisions about endangered species, the Service must use the best scientific <br />and commercial data available. Ongoing research results will provide that <br />necessary data. <br /> <br />Winter releases from Navajo Dam have maintained flows at or above 500 cfs <br />through winter months during most years since 1962 in the San Juan River at <br />Archuleta. The median pre-dam (1931 . 1962) winter flow (November through <br />February) at Archuleta was about 250 cfs, This increase in base flow at <br />Archuleta, combined with increased irrigation return flows in the winter, has <br />provided a median flow below Shiprock of over 1400 cfs during the post-dam <br />period compared to a median flow of 660 cfs pre-Navajo Dam. Releases from <br />Navajo Dam of approximately 300 cfs would produce an average winter base flow <br />of approximately 650-700 cfs near Bluff, Utah, The San Juan Recovery <br />Implementation Program's Biology Committee finds it necessary to test a winter <br />low flow in critical habitat for Colorado squawfish and razorback sucker, <br />prior to making a final recommendation on minimum winter flows. The <br />hydrographs provided by Reclamation that illustrate implementation of the <br />reasonable and prudent alternative, show winter releases from Navajo Dam of <br />300 cfs. Therefore, the Service finds it appropriate to prOVide winter test <br />flows of approximately 300 cfs during the research period. <br /> <br />The winter low flow test as required in Element 2 above would require releases <br />from Navajo Dam to be ramped down from SOO cfs to about 300 cfs in more than 6 <br />hours, but less than 24 hours. Flows would not be allowed to fall below <br />500 cfs in endangered fish habitat, as measured at the Shiprock gage, The 4 <br />month test would allow some assessment of biological response and should be <br />replicated in a subsequent year, to be valid. <br /> <br />In 1991, it was determined that the minimum stUdy period necessary to conduct <br />the required studies was approximately 7 years. Any inability to deliver the <br />flows under the third element of the reasonable and prudent alternative would <br />likely prolong the research period. To date, all flows required to complete <br />the research have not been prOVided, nor has the timing of the flows provided <br />been synchronous with the natural peaks of the Animas River, as requested. <br /> <br />During the research study period, it was anticipated that Navajo Dam would be <br />operated under a variety of scenarios (wet, average, and dry) to mimic a <br /> <br />4 <br />