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Interim Guidelines for the <br />Operation of Lake Powell <br />and Lake Mead <br />additional shortages being considered, after appropriate consultation, if Lake Mead <br />elevations drop below 1,025 feet mean sea level (msl). <br />The Defenders of Wildlife submitted a comment letter dated December 11, 2007, on <br />behalf of their organization, the National Wildlife Federation, the Pacific Institute, and <br />the Sierra Club regarding the updated draft Guidelines. The comments are limited to <br />information that was published in Appendix S of the Final EIS dated November 2, <br />2007. The letter offers a number of clarifying comments, raises concerns regarding the <br />appropriate mechanisms for consultation between federal and non-federal parties, and <br />raises detailed comments regarding the implementation of the ICS and Developed <br />Shortage Supply (DSS) components of the Guidelines. Reclamation thoroughly <br />reviewed the comments submitted and concluded that no changes to the Guidelines <br />were necessary. With respect to the issues regarding consultation, Reclamation will <br />continue to meet all legal obligations for appropriate consultation with non-federal <br />parties and believes that the commitments for continued consultation with the Basin <br />States can be implemented in a manner consistent with the provisions of applicable <br />federal law. Moreover, Reclamation believes that some of the concerns identified in <br />this comment letter have been addressed by Section 7.D of the updated draft Guidelines <br />posted on December 10, 2007, which provides that the Lower Colorado Regional <br />Director will establish procedures for the implementation of ICS and DSS after issuance <br />of this ROD. Reclamation will continue to work closely with all stakeholders in the <br />development of ICS and DS5 procedures and in the implementation and administration <br />of the Guidelines. <br />VII. Refinement of Operational Guidelines for the Preferred <br />Alternative in Response to Public Comments <br />Hydrologic modeling of the Colorado River system was used to determine the potential <br />hydrologic effects of each of the alternatives and also provided the basis for analyzing <br />the potential effects on other environmental resources (such as recreation, biology, and <br />energy, etc.). Nearly all modeling assumptions were common to each alternative; only <br />the assumptions specific to each alternative were different. This approach allowed a <br />relative comparison of the potential effects of each alternative compared to the No <br />Action Alternative and lead to the identification of the Preferred Alternative. <br />Historically, the determination of the annual release volume for Lake Powell could <br />change on a monthly basis throughout the water year. This approach afforded great <br />flexibility to respond to changing monthly runoff forecasts yet was practical to <br />implement since there were effectively only two operational tiers (a minimum objective <br />release of 8.23 maf per year or releases greater due to equalization or spill avoidance). <br />The annual release volume for Lake Mead, however, was essentially determined on an <br />annual basis primarily to provide a greater degree of certainty to water users with <br />respect to the water supply in the Lower Basin. The modeled operation of Lake Powell <br />and Lake Mead for all alternatives in the Final EIS was consistent with this past <br />operational experience and provided a valid basis for comparison. <br />ROD -Colorado River Interim Guidelines for December 2007 <br />Lower Basin Shortages and Coordinated 15 <br />Operations for Lake Powell and Lake Mead <br />