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<br />. <br /> <br />. <br /> <br />. <br /> <br />Comments on draft preliminary San Juan River Flow Recommendation <br />July 8, 1998 <br />Page 3 of5 <br /> <br />"Decision Tree" provided for Navajo operations is a start, but it does not prioritize the <br />many parts of the flow recommendations and it is not clear how hydrologic <br />conditions that are occurring in the basin are to be considered. <br />4. How will the Service evaluate whether a new project significantly affects the statistics <br />incorporated in the flow recommendations and whether or not a project may proceed? <br />Will the Service run the existing model with the proposed project inserted? If so, <br />whose responsibility will it be to make sure that the model is up-to-date? Since the <br />RiverWare model is proprietary and requires a license to use, someone will need to be <br />tasked with keeping the configuration and databases current. Further, the RiverWare <br />model is extremely complicated and very few people are now able to operate it. Does <br />the Service have personnel trained to operate it? <br />5. How will the Service determine whether or not the flow recommendations continue to <br />be satisfied? If the flow recommendations do not remain satisfied, what will happen <br />to projects already permitted or otherwise allowed to go forward? Once a project is <br />approved, there is no way of assuring that any specified flow amounts will remain in <br />the river during a given year since the flows are provided for on a statistical basis that <br />must be determined over a period of years rather than by any water right. What is the <br />period of years that will be used to determine whether or not a project or projects <br />have violated the flow recommendations? <br />6. The operation of Navajo Dam must be consistent with the dam's authorizing <br />legislation and state water rights. Colorado does not believe the issue of whether the <br />authority and water rights for Navajo Dam include storage releases for downstream <br />fisheries has been fully addressed. There is a distinction between bypasses and <br />storage releases. <br />7. The proposed "Decision Tree" and operating rules for Navajo Dam provide for a <br />determination of available water. However, the proposed rules do not describe how <br />that determination is to be made. The runoff period should be defined. Colorado <br />suggests April 15 to July 15. For what period is the determination of available water <br />to be made: April-July, annual or other? How are existing uses factored into the <br />determination? Is Reclamation's "RiverWare" model the definitive tool for <br />determining water availability? What risks are allowable to the safe yield of Navajo <br />Reservoir? <br />8. How does the Biology Committee justify attaching a frequency of once every 10- <br />years to the 10,000 cfs peak flow when such a condition, even with minimal new <br />development, does not occur for a IS-year period, if the conditions between 1958 and <br />1973, are repeated? <br />9. What is the justification for the peak flow pattern suggested? The baseflow from <br />which Navajo dam operations start to ramp up appears to be 500 cfs. The ramp up <br />and ramp down rates appear to be considered constant in the evaluations during any <br />given year based on the volume of water available. In other words, the rate at which <br />ramping up or down occurs will vary from year to year but not within the year. What <br />is the basis for this? On other rivers the ramp up and down rates have been fairly well <br />defined based on species and habitat concerns. Why shouldn't the rates be a constant, <br />predefined pattern based on the research? It seems to Colorado that there should be <br />more specific ramping rates and patterns since the trout fishery below Navajo is likely <br />