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WSPC12730
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Last modified
1/26/2010 4:34:16 PM
Creation date
3/27/2008 10:56:29 AM
Metadata
Fields
Template:
Water Supply Protection
File Number
8282.600.40
Description
Colorado River AOP Status Report
Basin
Colorado Mainstem
Author
USDOI/BOR
Title
Colorado River Reservoir Operations Status Reports Partial Part 1 2003, with staff comment
Water Supply Pro - Doc Type
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<br />feet per second (cfs) to a low of 5,000 cfs each day. The 20,000 cfs releases will be maintained for <br />approximately 9 hours each day (from about 11:00 a.m. to about 8:00 p.m.), while the 5,000 cfs <br />releases will be maintained for approximately 8 hours each day (from about 1:00 a.m. to about 9:00 <br />a.m.). The remainder of the hours will be transition releases where releases are between the daily <br />high and the daily low. This pattern will be maintained for 7 days a week during the January <br />through March time period. It should be noted that due to "real-time" power generation <br />considerations and "regulation" to stabilize the power system, actual releases may deviate somewhat <br />from this pattern. <br /> <br /> <br />The January through March high fluctuating releases are intended to benefit the endangered <br />humpback chub. Scientists have recognized that the humpback chub population has been in general <br />decline since highly fluctuating flows were curtailed in November of 1991. Those flows helped <br />keep the non-native fish, especially the rainbow and brown trout, in check. The trout are thought to <br />prey upon and compete with native fish such as the endangered humpback chub. <br /> <br /> <br />The high fluctuating releases will continue through March 2003. Monthly release volumes from <br />Glen Canyon Dam in February, and March 2003 will be 712,000, and 788,000 acre-feet, <br />respectively, which averages out to 12,800 cfs per day. <br /> <br />The experimental releases from Glen Canyon Dam received environmental clearances in December <br />2002. The flows were analyzed in an environmental assessment in accordance with the National <br />Environmental Policy Act. The experimental flows are the result of ongoing studies by scientists <br />from the United States Geological Survey and were recommended by the Glen Canyon Dam <br />Adaptive Management Work Group, a federal advisory committee. The experimental releases <br />address the decline of two key resources in the Grand Canyon: sediment and population viability <br />of endangered humpback chub. The Finding of No Significant Impact on the experimental releases <br />can be found at http://www.uc.usbr.gov/amplflow30nsi.pdf. <br /> <br />Drought conditions persist in the Colorado River Basin. The basin received some drought relief <br />during the months of September and October of 2002, but a dry pattern returned in early November. <br />Basinwide precipitation in December, 2002 was 60 percent of average and only 35 percent of <br />average in January. Snowpack in the Colorado River Basin is currently 70 percent of average (as of <br />February 7, 2(03). The February final inflow forecast issued by the National Weather Service is <br />calling for 4.6 million acre-feet of unregulated runoff into Lake Powell during the 2003 April <br />through July time period. This is 58 percent of average. <br /> <br />Inflow to Lake Powell continues to be significantly below average. Unregulated inflow into Lake <br />Powell in October, November, and December 2002 was 56, 69, and 57 percent of average, <br />respectively. Unregulated inflow in January, 2003 was 236,000 acre-feet, only 58 percent of <br />average. Inflow to Lake Powell is expected to remain below average through the winter and early <br />spring. <br /> <br />Drier than average conditions have now prevailed for the past three years in the Colorado River <br />Basin. Total unregulated inflow into Lake Powell in water year 2000 and 2001 was 62 and 59 <br />percent of average, respectively, and only 25 percent of average in 2002. Inflow in 2002 was the <br />lowest ever observed since the completion of Glen Canyon Dam in 1963. These low inflows have <br />reduced water storage in Lake Powell. The current elevation of Lake Powell is 3,614.3 feet (85.7 <br />feet from full pool). Current storage is approximately 13.1 million acre-feet (54 percent of capacity). <br />The water surface elevation of Lake Powell will likely continue to decline through the rest of the <br /> <br />
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