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COMMENTS OF U.S. ENVIRONMENTAL PROTECTION AGENCY RESPONSES TO U.S. ENVIRONMENTAL PROTECTION AGENCY <br />EPA -11 We have evaluated all alternatives with conservation savings at a <br />EPA -10 <br />there likely will be some impact to the aquatic community. It is <br />essential, therefore, that flow not be allowed to fall below aoo <br />level that requires a large monetary investment (approximately <br />(cont.) <br />cfs. This is the minimum flow needed to maintain the existing <br />aquatic community. <br />S10 million). We evaluated drought protection under both the 49- <br />Based on the above analysis, EPA has shown that the <br />year historical record and under an extended drought scenario. <br />recommended summer flow in the Instream Enhancement Alternative <br />We do not have access to data which would allow us to predict <br />is more than an analytical tool for alternatives comparison. Our <br />analysis shows that increased summer flows are a necessity to <br />farm behavior under shortage conditions nor to develop and <br />protect adequately the Platte River ecosystem. In EPA's scoping <br />comment letter dated February 11, 1993, EPA supported the <br />evaluate drought attenuation scenarios. <br />development of a Maximum Wildlife Benefits Alternative, now <br />called the Instream Enhancement Alternative. EPA commends FERC <br />for the inclusion of this alternative because it has provided <br />valuable insights on how the projects could be managed to provide <br />EPA <br />a more equitable balance of water use among all project purposes, <br />-12 The Modified Nebraska Plan improves the exceedance frequency <br />including irrigation. <br />of 950 cfs in August from the Baseline's 4.1 percent to 20.4 <br />EPA -11 <br />EPA recognizes, as does FERC in the RDEIS, the important <br />The exceedance frequency of 400 cfs improves from 20.4 <br />role that irrigated agriculture plays in the economy of Nebraska. <br />percent. <br />In keeping with this, the analysis in the final EIS for all <br />percent for the Baseline to 83.7 percent. In the context of the <br />alternatives, in particular the preferred alternative and the <br />7C <br />Instream Enhancement Alternative, should be expanded to more <br />other competing wildlife demands for higher instream flows, we <br />in <br />realistically explore how irrigation shortfalls could be <br />4 <br />reduced /overcome by increased water conservation, implementation <br />consider this summer flow improvement to be substantial. <br />C> <br />of conjunctive use to ground water /surface water via managed <br />releases of the ground water mound created through the projects' <br />operations, non - renewal of expired future water contracts, and <br />The recommended alternative, because it includes an <br />limiting drought protection to that of current operations rather <br />than the extended drought scenario now proposed in the RDEIS. <br />Environmental Account, provides the account manager the <br />necessary flexibility to efficiently manage instream releases. <br />Instream Flow Releases for the Maintenance of the Platte River <br />Ecosystem <br />EPA -12 <br />In addition to the inability of the preferred alternative to <br />substantially reduce exceedences of the Nebraska state water <br />quality standard for temperature, the preferred alternative also <br />requires modification regarding the amount, timing and duration <br />of instream flow releases to more efficiently meet all target <br />flows for fish and wildlife. The proposed environmental account, <br />while a good idea in principle, currently does not provide <br />adequate flow or incorporate allocation procedures that would <br />effectively allow for fishery habitat requirements past the early <br />summer. <br />Based on a review of the monthly flow duration curves in <br />Section C -2 (C -61 through C -72) of the RDEIS, it appears that the <br />design of the preferred alternative makes it difficult to manage <br />efficiently instream flow releases. If less water were to be <br />released during November through March, more would be available <br />for release in May through September. These releases would serve <br />