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Protecting Grand Canyon Hey there- welcome aboard the
Grand Canyon River Guides Website. We want to tell you about ourselves,
what we do, and why you might care.
How Do You Fit In?-- About 800 of us are Guide Members,
having worked in the river business. The rest of us are General Members-folks
who have gone down the river with us or on their own, hiked, fished, researched
or generally fallen in love with the place. It's important for us to connect
with as many guides as possible, both commercial and private, so that
we may accurately |
Glen Canyon Report - Sept 2008 Glen Canyon Dam Operations The water year release volume from Glen Canyon Dam in water year 2008 is being determined under the Equalization Tier of the Interim Guidelines. Under the Equalization Tier, the water year release volume in 2008 is being adjusted each month in order to target an end of water year elevation at Lake Mead of 1105 feet above sea level. Based on system conditions as of August 26, 2008 and projected operations at Lake Mead for the remainder of water year 2008, the release volume from Glen Canyon Dam for September 2008 will be set to 719 kaf which corresponds to the steady release rate of 12,083 cfs. This adjustment is being made now in order to implement the steady flows which are to begin on September 1, 2008. Upper Colorado River Basin Hydrology The unregulated inflow to Lake Powell during the April through July period was 8.84 maf (111% of average). Unregulated inflow to Lake Powell from now to the end of October is projected to be above average (106%). The long range outlook for water year 2009 projects that the most probable unregulated inflow to Lake Powell will be 91% of the 30-year average (1971-2000) however there is a wide range of uncertainty associated with these long range outlooks. Upper Colorado River Basin Drought In the summer of 1999, Lake Powell was essentially full with reservoir storage at 23.5 million acre-feet, or 97 percent of capacity. Inflow to Lake Powell in 1999 was 109 percent of average. The manifestation of drought conditions in the Upper Colorado River Basin began in the fall months of 1999. A five year period of extreme drought occurred in water years 2000, 2001, 2002, 2003, and 2004 with unregulated inflow to Lake Powell only 62, 59, 25, 51, and 49 percent of average, respectively. Lake Powell storage decreased through this five-year period, with reservoir storage reaching a low of 8.0 million acre-feet (33 percent of capacity) on April 8, Drought conditions eased in water year 2005 in the Upper Colorado River Basin. Precipitation was above average in 2005 and unregulated inflow to Lake Powell was 105 percent of average. Lake Powell increased by 2.77 million acre-feet (31 feet in elevation) during water year 2005. But as is often the case, one favorable year does not necessarily end a protracted drought. In 2006, there was a return to drier conditions in the Colorado River Basin. Unregulated inflow to Lake Powell in water year 2006 was only 71 percent of average. Water year 2007 was another year of below average inflow with unregulated inflow into
Lake Powell at 68 percent of average. Over the past 9 years (2000 through 2008,
inclusive), inflow to Lake Powell has been below average in all but two years (2005 and
2008). Drought conditions have eased in water year 2008 with above average inflows to
the main stem Colorado River reservoirs with the exception of Flaming Gorge and
Fontenelle Reservoirs. Reservoir storage in the Colorado River Basin, however, is still
below desired levels with the overall Colorado River system storage (above Lake Mead)
projected to be about 58% of capacity at the end of water year 2008.
Reservoir storage in Lake Powell and Lake Mead has decreased during the past 8 years
but is projected to increase by the end of water year 2008. Current reservoir storage in
Lake Powell is 61 percent of capacity. Storage in Lake Mead is 46 percent of capacity. |
Please E-mail comments, suggestions, etc. regarding this web site to: GCRG Webmaster
E-mail all other Grand Canyon River Guides - related stuff to: gcrg@infomagic.net
Or contact Grand Canyon River Guides directly at:
P.O. Box 1934
Flagstaff, AZ 86002
Phone: (928) 773-1075
FAX: (928) 773-8523
visitors since October 5, 1999.