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Lake Powell in peril?

Cliff Thompson

Lake Powell, the 25 million acre-foot reservoir formed by Glen Canyon Dam in 1968, is now less than half full.It’s not a philosophical question about the reservoir being half empty or half full. It didn’t fill up last year. Since the drought of 2002, it’s draining faster than it’s filling. While water experts admit there are lot of “ifs” in their calculations, they are beginning to get concerned. Eagle County’s Eagle River is a tributary of the Colorado River.If the drought, now in its third year, continues at current rates -and forecasts vary – the huge lake could be drained by 2010, leaving Colorado to supply 7.5 million acre-feet it agreed to supply downstream states under the 1922 Colorado River Interstate Compact.That seven-state agreement outlines how the river’s water resources will be shared. Each year, 8.23 million acre-feet of water are released from the reservoir and during the last three years of drought, there has been a net loss in the reservoir of 1.5 million acre-feet a year between what’s flowing in from upstream and what’s being released. Mexico gets 1.23 million acre-feet annually.But what happens if the drought continues or even deepens and there’s not enough water to go around?”People have hard time realizing what a significant drought we are experiencing region-wide,” said water attorney Scott Balcomb of Glenwood Springs, who is the Colorado Representative to the Compact. “It never seemed possible there wouldn’t be enough river to go around. It’s happening right now. These were things we never thought of.”Balcomb addressed a joint meeting of the Eagle River Water and Sanitation District and the Upper Eagle Regional Water Authority Thursday, outlining what the possibilities for the future could be. He says what happens will depend entirely on the weather patterns. The more rain and snow, obviously, the better.”It’s not a good time to panic,” he said. “It is time to start thinking about the issue.”Balcomb said Coloradans need to start devising a plan to deal with the eventuality that the lake will be drained, and what will happen when it is.”It’s been real dry for three to four years,” Balcomb said. “We don’t have any assurances it’s not going to be dry the next three or four.”The Doomsday scenario for the river may actually represent what it will be like when the entire seven-state area the river serves is built out, and all the water has been divided up and used, he said. Colorado, California, Nevada, Arizona, New Mexico, Utah and Wyoming all share the Colorado River and its tributaries. The river is a huge source of irrigation for California’s Imperial Valley, where agriculture is king. It also powers greater Las Vegas, one of the country’s fastest growing areas.The Compact overrides the appropriation doctrines which each state observes within the Colorado River basin.What about me?If Lake Powell does go dry, what does it mean if you live in Eagle County?Surprisingly, little. Even if the lake is drained by successive years of drought, Eagle County will be in pretty good shape compared to other parts of the state because a fair number of the area’s water rights predate 1922, said attorney Glenn Porzak, who represents local water districts. That means water here can be used for irrigation instead of flowing downstream to meet the needs of the lower Colorado River basin states.But along Colorado’s dry Front Range where 80 percent of Colorado’s population is centered, a dry Lake Powell could be a big problem.”It could be a catastrophe for the Denver area,” Porzak said.Downstream states would place a “call” – a demand for the water they’re entitled to under the terms of the Compact. That could preclude users in Colorado from having any. While it’s a bit of a doomsday scenario, it is being actively discussed.Eric Kuhn, manager of the Colorado River Water Conservation District, wrote in November that based on worst case modeling projections of the river during a prolonged drought: “During the call period, the impacts on the Upper Basin (Colorado) would be extreme … projects such as the Colorado Big Thompson Project, Central Utah Project, San Juan-Chama Project, Dillon/Roberts Tunnel System, Fryingpan Arkansas Project … could not divert a drop of water.”All those water diversion projects take water from tributaries of the Colorado River and they would be shut down if Lake Powell is drained. So far this year Lake Powell is 112 feet below what’s considered an average level, and it has 10.6 million acre-feet or 48 percent of its capacity. That’s enough water to supply 41 million people for a year.Salty waterBut if the lake is drained, it’s going to create more than just shortages of water.”There are some serious water quality problems created when you lower the lake,” said Kuhn. “Saline water tends to go to the bottom of the lake.”Much of the Colorado River flows through an ancient seabed, and runoff carries salt into the lake. That salt concentrates as the volume of water shrinks. As the lake drops, more and more water has to be released from the bottom of the pool.Predictions of the drought continuing, Balcomb said, have been based on examination of the growth rings of centuries-old trees. This hydrodendrochronology is a living record of drought. In dry years, trees don’t grow as much as in wet years, and growth rings are closer together. Those trees show periodic droughts throughout the centuries, Balcomb said, some lasting 30 years.But examining tree rings is an inexact science. Tree rings may not accurately reflect extremely wet years because they can grow only so much in a single growing season, and their rings may not reflect how wet it was. Extremely wet years could refill the reservoir.”What we’re facing today is not necessarily all that historically unusual,” said Kuhn. In November Kuhn outlined his concerns about Lake Powell in a letter to water administrators within the river basin. “If we have a series of average years, we’ll fill up Powell. If we have four more years of dry weather it will cause a problem.”Kuhn’s letter also outlines historical data that suggest that the 15 million acre-feet per year average annual flow the Compact is based upon overestimated what was available in the Colorado, a University of Arizona/ Colorado State University study concluded.”The long-term flow of the river at Lee’s Ferry (Arizona) is in the range of 13.5 to 13.8 million acre-feet, not 15 million,” he wrote in his letter. That estimation may have been based on average flows during a wet period. In a dry period such as we’re in now, historic data from tree rings suggests the flows could maintain just 11.1 million acre-feet a year.”Hydrodendrochronology is controversial. Critics say tree rings underestimate wet years,” Kuhn said. “Empirical evidence show tree rings do a good job of representing dry years.”The wild card in the deck is the weather. Global warming is another factor that earlier estimates of the river’s flow probably didn’t have to calculate. It could make the drought more severe. In Glacier National Park Montana, and elsewhere around the world, glaciers are shrinking faster than at any time in their history. Its effects aren’t entirely esoteric. Right now New Mexico is in the severest drought in history, Balcomb said.Eagle County’s snowpack, the wellspring of its water, is now slightly less than it was during the same period in the drought of 2002. Snowpack in the Colorado River basin in Colorado is 80 percent of average or less.In addition to being a storage reservoir Lake Powell has also become a popular recreation area for millions of waterborne enthusiasts.Balcomb concluded his presentation to the board: “What we need now is snow, and lots of it.”Cliff Thompson can be reached via e-mail at: or by calling 949-0555 ext. 450.


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