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<br />'- <br /> <br />02/14/96 10: 06 <br /> <br />tt303 245 6933 <br /> <br />FISH" WILDLIFE ...... ewCB <br /> <br />1aI004 <br /> <br />under emergency conditions or where deviation is required to stay within <br />the Corps of Engineers flood operating rules. <br /> <br />6. At the end of the research period, Navajo Dam shall be operated to mimic <br />a natural hydrograph (see Appendix A) for the life of the <br />Animas-La Plata Project based on year-round flow recommendations <br />developed by the San Juan River Basin Recovery Implementation Program's <br />Biology Committee and approved by the Coordination Committee, SerVice <br />and Reclamation. <br /> <br />7. The binding agreements (Appendix B) to legally protect the reservoir <br />releases (for both the study period and for the life of the Animas-La <br />Plata Project) to and through the endangered fish habitat to lake Powell <br />that were executed in support of the 1991 biological opinion for the <br />Animas-La Plata Project will continue with all force and effect. The <br />Bureau of Reclamation will continue to participate in and contribute <br />funding for the San Juan Recovery Implementation Program that was <br />established by cooperative agreement on November 1, 1992 (Appendix C) in <br />accordance with funding agreements that are reached among Recovery <br />Program participants. <br /> <br />Discussion <br /> <br />The jeopardy and adverse modification conclusion in this biological opinion is <br />based on full Project development which would result in an average annual <br />depletion of 149,220 acre-feet of water. To offset the likelihood of jeopardy <br />and adverse modification of critical habitat, the reasonable and prudent <br />alternative presented herein includes construction and operation of the <br />Phase I, Stage A of the Project, which would initially result in a net annual <br />depletion of 57,100 acre-feet, a considerably smaller depletion. However, <br />even this smaller depletion is biOlogically acceptable only if all elements of <br />the reasonable and prudent alternative are fully implemented. Therefore, <br />Phase I, Stage A could not exceed 57,100 acre-feet until all elements are <br />fully implemented. This would require that Reclamation operate Navajo Dam to <br />provide the flexibility to mimic a natural hydrograph as directed by the <br />Biology Committee and as demonstrated by the model runs that show availability <br />of 300,000 acre-feet of water 96 percent of the water years for the endangered <br />fishes. In order to achieve this, a low winter flow (about 300 cfs), if <br />hydrologiC conditions permit, below Navajo Dam would be required. Therefore, <br />until low winter flows, below the existing 500 cfs minimum become part of <br />Navajo Dam operations, Phase I, Stage A could not exceed an annual depletion <br />of 57,100 acre-feet. <br /> <br />The operation of the full scale Project (Figures 1-18, Appendix A) would <br />result in a significant reduction of spring. peak flows through the endangered <br />fish habitat in the San Juan River, while the operation of the Project in <br />accordance with the reasonable and prudent alternative takes much less water <br />on a fairly steady basis throughout the year. When one compares the initial <br />depletion of the Project to the hYdrograph of existing conditions with the <br />Navajo Dam operated to mimic a natural hydrograph (Figures 1-18, Appendix A), <br />there 1s negligible change to the hydrograph shape and/or timing of spring <br />peak flows with the reoperation of the Navajo Dam. This is important in order <br /> <br />3 <br />