This week, to see how climate change will pull a nasty water surprise on the desert Southwest, you only need to look at one river.
Lake Powell is the giant reservoir on the Utah-Arizona border that backs up behind Glen Canyon Dam and is the linchpin for managing the Colorado River. The Colorado basically makes modern life possible in seven western states by providing water for some 40 million people and irrigating 4 million acres of crops. It is also depended upon by 22 native American tribes, 7 national wildlife refuges and 11 national parks.
As soon as Monday, the federal government’s Bureau of Reclamation will announce the results of some very serious number crunching and model running focused on falling water levels in Lake Powell. It is widely expected that the bureau will announce that there is a serious water shortage and that for the first time in the 50-year-history of the dam, the amount of water that will be released from the reservoir will be cut. Not just cut, but cut by 750,000 acre feet — an acre foot being enough water to cover an acre one foot deep. That’s more than 9 percent below the 8.23 million acre feet that is supposed to be delivered downstream to Lake Mead for use in the states of California, Nevada and Arizona and the country of Mexico under the 81-year old Colorado River Compact and later agreements.
It will be, in the somewhat dry appraisal of Anne Castle, the assistant secretary of the Interior for water and science who oversees the bureau, “very unusual.”
Unusual, and unprecedented, but not totally unforeseen.
Six years ago, following another period of dropping water levels in Colorado River reservoirs, the federal government and the seven states that rely on the river agreed on “interim operating guidelines” for apportioning water in the event of shortages. That step is part of a longer-term process of trying to figure out how to deal with a river system that is no longer providing the volumes of water the southwest long ago came to expect. The guidelines require the secretary of the Interior each year to assess what the water supply looks like for the lower Colorado River basin states of California, Nevada and Arizona. The secretary can choose among three declarations: normal, surplus or shortage. This year the smart money is on shortage.
Lake Powell, and its downstream cousin, Lake Mead — formed by Hoover Dam — are the two largest reservoirs in the U.S. They are the main plumbing fixtures for dividing up Colorado River water under a complex set of agreements known as the Law of the River. The Colorado River Compact is the most important of those agreements, and requires that the lower basin states and upper basin states (Colorado, New Mexico, Utah and Wyoming) each get 7.5 million acre feet a year. Mexico gets another 1.5 million under a 1944 treaty.
All good in theory, but the river was divided up in the 1920’s, a wet period when river flows were high. Times, and flows, have changed.
Now, the two reservoirs are giant flat water billboards advertising what climate change is doing to the American West. Persistent drought, and diminished snow runoff in the Rocky Mountains, have drastically shrunk the two reservoirs. Both are now less than half full, and both sport bathtub rings that show in dramatic fashion how high the waters used to be. Inflows to Powell this year are about 42 percent of average.
Some people believe that Lake Powell is toast, that it will never fill up again. For a lake that attracts a couple of million visitors a year who spend lavishly on houseboats, fishing gear, sun tan lotion and beer, that has some serious economic implications.
It could get worse.
Lake Powell is a moneymaker in other ways. Glen Canyon Dam and its hydroelectric turbines, produce 1320 megawatts of electricity, enough for about 1.3 million people. That yields something like $125 million every year, and that pot of money pays for the operations of much of the entire Colorado River Storage Project, and a host of vital environmental restoration programs.
Droughts do happen from time to time. But the hydrological cycle is being stressed by more than just natural variations. As greenhouse gases trap more heat in the atmosphere, dry areas like the Southwest will get drier and drier.
Last month, Eric Kuhn, the general manager of the Colorado River Water Conservation District in western Colorado, which looks out for the state’s interest in river issues, sent a memo to his board of directors outlining the likelihood of a shortage declaration by the Bureau of Reclamation.
“A one year shortage is probably not a big deal,” wrote Kuhn. But he made it clear that a multi-year shortage, and some very serious repercussions, are quite possible. In 2015, Kuhn wrote, the water level in Lake Powell may fall low enough — below what is known as minimum power head — to shut down the production of hydroelectric power. “The financial impacts could be substantial,” he wrote.
“The scary scenario for the Lower Basin is a multi-year shortage,” according to Kuhn’s memo. Among the impacts: big water delivery cuts to Nevada and Arizona, power production from Hoover Dam is “dramatically reduced,” recreation on Lake Meade “becomes marginal.”
Long term, the outlook is particularly grim. Late last year, a joint study by the Bureau of Reclamation and the seven river basin states looked at water supply prospects over the next half century. It projects average yearly imbalances between supply and demand of 3.2 million acre feet by 2060. An acre foot is about what a typical suburban household uses in a year.
Asked what she thinks of Kuhn’s analysis, Bureau of Reclamation overseer Castle told Climate Progress that “it’s based on some pretty draconian scenarios, but it’s not out of the realm of possibility.” But she predicts that ultimately “the states and the federal agencies together with all the stakeholders on the river will come together around a management plan that will attempt to ensure that we don’t hit critical [water levels] in either Powell or Mead.”
Outside groups are looking for solutions, too, and one — the Glen Canyon Institute, which advocates for a free-flowing Colorado River and the restoration of the magnificent canyon inundated by the dam and the filling of Lake Powell — sees at least a partial answer in its “Fill Mead First” plan.
Citing research that shows large water losses in Powell because of seepage into the porous sandstone banks, Glen Canyon Institute executive director Christi Wedig says Fill Mead First could save 300,000 acre feet of water a year, equivalent to Nevada’s annual allocation. The plan would allow Lake Mead to fill first, and would keep Lake Powell at the depth just above minimum power head. It would, said Wedig, bring substantial environmental benefits to the Grand Canyon, and would reveal many of the hidden treasures of Glen Canyon and stimulate tourism there.
Before the dam and lake erased it, few people had explored Glen Canyon. Author and photographer Eliot Porter described it in his book “The Place No One Knew”
“The big features, the massive walls and towers, the shimmering vistas, the enveloping light, are all hypnotizing, shutting out awareness of the particular,” he wrote. “Later you begin to focus on the smaller, more familiar, more comprehensible objects . . . the velvety lawns of young tamarisks sprouting on the wet sand bars just vacated by the retreating flood . . . the festooned, evocative designs etched into the walls by water and lichens. It is an intimate canyon.”
“Glen Canyon has been unexplored since 1963,” said Wedig. “There is a huge opportunity to capitalize” on its re-emergence with new tourism that focuses more on exploring vivid canyons and less on partying aboard 60-foot houseboats.
Castle declined to comment on the Fill Mead First idea. But she does say that current circumstances on the Colorado River are “unprecedented.”
The last 14 years on the Colorado River, she says, have been the driest years since records began being kept in the late 1800’s, and based on tree ring studies among the driest 14 year periods in the last 1,200 years.
“If you say climate change doesn’t have an impact, you’re smoking something,” Castle concludes.