In 1956, construction of Glen Canyon Dam began. The dam would generate hydropower, promote recreation and keep silt from filling up Lake Mead, but its main purpose was to create Lake Powell to serve as a water savings account and even out the Colorado River’s fluctuating flows. By storing water during wet years for use during dry ones, it would help the Upper Basin states comply with the Colorado River Compact and ensure that the river’s flow at Lees Ferry was not depleted “below an aggregate of 75,000,000 acre-feet for any period of ten consecutive years.”
Now, all its functions — except capturing silt — are imperiled, and, ironically, the dam itself may cause the Upper Basin to violate the compact’s non-depletion clause.
More than two decades of drought have nearly drained Lake Powell’s savings account. This winter’s lack of snow has made things worse, forcing federal dam operators to take extraordinary measures to keep the reservoir from dropping below critical levels this summer and preserve its hydropower production and Glen Canyon Dam’s viablity as a water storage facility. But once downstream releases are reduced, the Upper Basin could end up violating the compact.
Both the compact and the dam were developed for a much more abundant river. Now, increasingly arid times are poised to render both obsolete.
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Illustrations by Emma Mary Murray/High Country News
SOURCES: Bureau of Reclamation, National Oceanic and Atmospheric Administration, Natural Resources Conservation Service, U.S. Geological Survey, Central Arizona Project.
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