Tuesday, Apr 1, 2008
Lake Mead’s rapidly dropping waters are the subject of two recent national news articles – one in Science News, the other in Time.
The article in the February 23rd edition of Science News, written by Sid Perkins, reports the findings of a new Scripps Institution of Oceanography study which says that “(if) climate changes as expected, and future water use goes unchecked, there's a 50 percent chance that Lake Mead — one of the southwestern United States' key reservoirs — will become functionally dry in the next couple of decades…”
Over the past century, an average of about 18.5 cubic kilometers of water has flown into the lake annually. Of that amount, about 2.1 cubic kilometers evaporate or soak into the ground, leaving roughly 16.4 cubic kilometers. Since the demand for water and hydropower generated by Hoover Dam last year reached 16.6 cubic kilometers and is projected to rise to 17.4 cubic kilometers by 2030, demand will exceed supply even in optimal conditions. But some climate studies suggest that the Colorado’s flow will drop between 10% and 30% over the next 30 to 50 years.
The lake is now at about 50% capacity, writes Perkins, but will likely drop substantially in the future. “If current allocations of water persist, there's a 50 percent chance that by 2023 Lake Mead won't provide water without pumping, and a 10 percent chance that it won't by 2013. Moreover, there's a 50 percent chance that Hoover Dam won't be able to generate power by 2017, the researchers estimate.”
For a copy of that article, go to http://www.sciencenews.org/articles/20080223/fob2.asp
The Bryan Walsh article in the March 20th issue of Time is entitled “Postcard: Lake Mead.” It also reports on the Scripps study, adding details on what the drop looks like at the park. Here are the opening paragraphs:
“There is no shortage of ways to see just how short of water Lake Mead is. You can count the white bathtub rings of mineral deposits on the bedrock walls of the sprawling, 250-sq.-mi. (647 sq km) reservoir, indicating the old high-water mark – now left nakedly exposed 100 ft. up. You can look at the docks that have been moved repeatedly, chasing the receding lake. Or you can simply read a line graph at the reservoir's visitor center, which tracks the water elevation of Lake Mead since it was created by the construction of the Hoover Dam in 1935. After years of relative stability, starting in 2000 the graph resembles the record of a stock-market crash. The visitor center's chart stops at 2006, but as a park ranger tells me, ‘It just keeps going down from there.’
“The worrying question is whether it will ever stop. A major, prolonged drought, combined with rapid population growth in nearby urban areas like Las Vegas, has stressed Lake Mead and the rest of the Colorado River Basin, which provides water to farmers and cities from Colorado to Southern California. Now there are fears that global warming could drastically reduce the Colorado River's flow – even as the Southwest continues to expand. Scientists at the Scripps Institution of Oceanography in La Jolla, Calif., last month estimated that there is a 50% chance that Lake Mead could be effectively dry by 2021 if the climate changes as forecast and water use is not curtailed.”
The Time article is not readily available on line, but, as noted, can be found in the March 20th edition.
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