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<br />Statement (GCD-EIS, Bureau of Reclamation 1995) and 1996 Record of Decision to operate
<br />Glen Canyon Dam as described in the preferred alternative of the EIS, with slight modification,
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<br />The Grand Canyon Protection Act of 1992 (pL. 102-575) requires the Secretary of the Interior
<br />to operate Glen Canyon Dam "...in such a manner as to protect, mitigate adverse impacts to, and
<br />improve the values for which Grand Canyon National Park and Glen Canyon National Recreation
<br />Area were established, including, but not limited to natural and cultural resources and visitor
<br />use, "Section 1802(a)]. The operation as described in the ROD is designed to preserve a mass
<br />balance of sand, primarily for use as camping beaches and substrate for riparian vegetation,
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<br />The ROD selected the modified low fluctuating flow alternative (MLFF) as the operation of Glen
<br />Canyon most likely to meet the stated goals of the GCD-EIS, The MLFF has a minimum release
<br />of 5,000 cubic feet per second (cfs) between 7:00 p,m, and 7:00 a,m. (at night), and 8,000 cfs as a
<br />minimum release from 7:00 a.m, to 7:00 p,m, (day time flows), The maximum release is 25,000
<br />cfs, with a maximum daily flow range of 5,000 cfs, 6,000 cfs or 8,000 cfs, depending on the
<br />monthly release volume (during low, medium or high volume months, respectively), Ramping.
<br />rates under the ROD are 4,000 cfs/hr up and 1,500 cfs/hr down, The ROD also provides for a I
<br />to 2 week-long beach/habitat-building flow, It also allows for beach/habitat-building flows to be
<br />considered in other months, to coincide with late summer rainfall events, The high, steady,
<br />releases will be used to evaluate the applicability of high flows as a strategy for future adaptive
<br />management oCthe Colorado River, High flows are intended to restore part of the natural range
<br />of variability under which the ecosystem evolved.
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<br />Flooding was an essential characteristic of the pre-dam river, Current dam operations have
<br />virtually eliminated this dynamic element of the natural ecological process, Although a program
<br />of reduced daily flow fluctuation (Interim Operations) was implemented in 1991 to conserve a
<br />mass balance of tributary-de1;ived sand, occasional high flows are thought to be required to
<br />restore high elevation sand deposits and characteristic aquatic habitats, such as backwaters,
<br />Backwaters are used as rearing habitats by young native fish,
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<br />The proposed 1997 Fall Test flow will improve understanding of how floOding influences
<br />ecosystem.geomorphology, biological and cultura1 (archeological and traditional land use)
<br />resources, and ecosystem processes. Data collected during the 1997 Fall Test flow will
<br />demonstrate in conjunction with other test data the extent to which planned flooding can be used
<br />as an ecosystem management tool. A previous test of a beach-habitat building flow was
<br />conducted in March, 1996.
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<br />DESCRIPTION OP THE 1997 FALL TEST FLOW
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<br />Description of Flow
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<br />The 1997 Fall Test flow is scheduled to begin at noon with upramp releases at a rate of 4,000
<br />cubic foot per second (cis) each hour until the desired release rate of 31,000 cfs is reached at
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