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Last modified
7/14/2009 5:02:32 PM
Creation date
5/20/2009 3:00:27 PM
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UCREFRP
UCREFRP Catalog Number
8031
Author
U.S. Department of the Interior.
Title
Fish and Wildlife Service Final Biological and Conference Opinion on Lower Colorado River Operations and Maintenance - Lake Mead to Southerly International Boundary.
USFW Year
1997.
USFW - Doc Type
\
Copyright Material
NO
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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />BIOLOGICAL OPINION <br /> <br />Proposed Action <br /> <br />reservoir levels in Lake Mead. <br /> <br />Reclamation actions involving projects in the planning or implementation phase or that are <br />mitigation for past projects may require additional section 7 consultation to address site-specific <br />issues. Other activities not expressly included in the following description of the proposed action <br />are not covered under this consultation, such as, but not limited to, changes in criteria for <br />developing Annual Operating Plans or for declaring water surpluses (beyond the paramete rs in the <br />description of the proposed action, below), new water contracts, new power production or <br />transmission facilities, and changes in flood control regulations by the Army Corps of Engineers. <br /> <br />Actions <br /> <br />1. Flood control <br /> <br />Flood control operations have the first priority on the LCR as mandated by the Boulder Canyon <br />Project Act. Section 7 of the Flood Control Act of 1944 established that the Secretary of War <br />(now the Army Corps of Engineers [COED will prescribe regulations for flood control for projects <br />authorized by that Act. The CaE is responsible for developing the flood control operation plan for <br />Hoover Dam and Lake Mead as indicated in 43 CFR 208.11. The plan is the result of a <br />coordinated effort by the CaE and Reclamation, but the CaE is responsible for providing the flood <br />control regulations and has authority for final approval. Any deviations from the flood control <br />operating instructions must be authorized by the CaE. The Secretary is responsible for operating <br />Hoover Dam in accordance with these regulations; therefore, Reclamation has only limited <br />discretion in managing Lake Mead elevations for flood control. <br /> <br />Flood control regulations promulgated by the CaE for Lake Mead were established to deal with <br />two distinct types of flooding: rain and snowmelt. Snowmelt constitutes about 70 percent of the <br />annual runoff of the Colorado River into Lake Mead. Lake Mead's uppermost 1.5 maf of storage <br />capacity, between elevations 1219.6 and 1229.0 mean sea level (msl), is allocated exclusively to <br />control floods from rain events. Within this capacity allocation, 1.218 maf of flood storage is <br />above elevation 1221.4, which is the top of the raised spillway gates. <br /> <br />Flood control regulations specify that once flood releases exceed 40,000 cubic feet per second <br />(cfs), the releases shall be maintained at the highest rate until the reservoir drops to elevation <br />1221.4. Releases may then be gradually reduced to 40,000 cfs until the prescribed seasonal storage <br />space is available. The flood control regulations set forth two primary criteria to deal with <br />snowmelt: 1) preparatory reservoir space requirements, and 2) application of runoff forecasts to <br />determine releases. <br /> <br />In preparation for the coming year's season of snow accumulation and associated runoff, <br />progressive expansion of total Colorado River system reservoir space is required during the latter <br /> <br />10 <br />
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