Area’s water future looks like 2002
EAGLE COUNTY – In July 2002, while descending from Peak 1 near Frisco, I saw something that haunts me still. An uncommonly thin snowpack that year had been chased by a windy spring that came weeks early, hot and dry. Forest fires and heat waves soon followed. Farm crops withered, suburban laws crinkled, and foreheads wrinkled at this long-ignored limit to growth. Water was front-page news.Dillon Reservoir was the emblem in Colorado for that touchy, grouchy summer. Blue segued to brown, water to mud and then dry sands. Hiking down from timberline that hot afternoon, I looked up to see a dust devil spinning through an area once marked by sailboats. It was like hearing a funeral dirge at a wedding.Climate scientists caution against making too much out of any one year when talking about global warming. Still, in looking ahead at a planet redefined by warmth, the future they describe in Colorado and the Southwest looks and feels very much like 2002.This is a land where aridity rules. Any map reveals as much. Large expanses from Denver to Los Angeles are public lands. Rugged topography and short-growing seasons explain why some of these lands were not homesteaded. But the larger reason is the lack of native moisture.Oh, there is water, but mostly – about 85 percent in the West – it comes from snow in the high mountains. This snowpack is like a giant reservoir for the farms and cities of Denver, Las Vegas and San Diego. The focal point for this civilization is the Colorado River and its tributaries.Paradigm shiftAs this drought that has afflicted the region since 1999 has made clear, the Colorado River is a resource badly strained. No extra water makes it to the Sea of Cortez even during wet years. Now, water managers are getting a better idea of how much drier this region was for much of the past 1,000 years. This past century was actually unusually wet.Whether this current drought is a result of a normal climatic fluctuation or is an early signal of global warming really doesn’t matter. Either way, a fundamentally new way of looking at the river is taking hold.The new reality is crystallized in photos of Lake Powell, now sitting only 40 percent full, or the other big storage vessel, Lake Meadow, at 54 percent of capacity.”The Colorado River is the canary in the coal mine for global warming,” says Eric Kuhn, general manager of the Glenwood Springs-based Colorado River Water Conservation District. “You have a system where the demand and supply are so close that a small change of 10 percent in the annual flow at Lee’s Ferry (in Arizona, the divide between upper and lower basin states) could cause a major disruption. A 10 percent change wouldn’t make much difference on the Fraser River in British Columbia or on the Missouri.”Already, water managers are trying to imagine what this disruption would look like. Allocation of the water among the states is governed by the Colorado River Water Compact of 1922. That compact was signed after a period of what was, in retrospect, extraordinary wetness. The river has carried the same volume only occasionally since then.
Even so, there were no major problems except – from the perspective of politicians in Colorado – that California was “stealing” Colorado’s unused share of water. The presumption in Colorado was that this water would eventually be used to feed the growing cities along the Front Range and otherwise enable economic development.Fear upside downThat fear is now being turned upside down. Given how little water the river is now carrying each year, arguably the compact governing the river will call upon Colorado and other upper-basin states to allow more water to flow down to California, Nevada and Arizona.This possibility has the full attention of Glenn Porzak, a Boulder-based water attorney who represents most major water groups and companies in Summit County and the Eagle Valley.”Regardless of whether it’s your normal climatic cycle or the result of global warming, the effect is the same,” says Porzak. “One need only look at what is happening at Lake Powell to see that if things to continue, we are going to enter an era of Colorado River Compact calls, which heretofore had not occurred, and that will dramatically change the landscape. I really think people need to pay attention.”The link between the current drought and global warming is still unclear, says Brad Udall, managing director of the University of Colorado-National Oceanic and Atmospheric Administration Western Water Assessment. Udall notes new research that shows droughts of the 13th century – about the time the Ancestral Pueblo abandoned Mesa Verde and Chaco Canyon – were decades in length.”There’s no way to attribute this drought to climate change,” he says.Still, water managers are increasingly thinking about the specter of global warming. “I think it’s in the back of everybody’s mind,” acknowledges Porzak.Danger in degreesAny way you cut it, global warming will redefine the landscape of Colorado and the Southwest. Hotter is the most fundamental difference. It makes winters shorter and summers longer. During those longer summers, even if precipitation remains the same, warmer temperatures leave forests drier and more susceptible to wildfires. Precipitation is less clear. But the most important thing to remember is that if temperatures rise, precipitation must also rise – just to stay equal. That’s because evapotranspiration – the return to the atmosphere of water through either evaporation or respiration by plants – will reduce precipitation by 8 to 20 percent.Shorter, warmer winters spell changes. More rain, which drains more rapidly than snow, can be expected. But with shorter winters, spring comes earlier, with runoffs cresting in the rivers not in June, as has been the case, but in May or even April.
Already, anecdotal evidence of such changes is found. Records in Aspen show the frost-free season has expanded about two weeks into spring, compared with a half-century ago. Dillon Reservoir during the last decade has lost its winter ice more rapidly. And the Colorado River below Glenwood Springs is peaking with runoff a few days earlier.On the West Coast, changes have been even more profound in response to the increase of 1.44 degrees Fahrenheit during the last half-century. The peak of the annual runoff in the Sierra Nevada now comes as much as three weeks earlier than it did in 1948. “The mountain ranges are essentially draining and drying earlier,” said Dan Cayan, a climate researcher with the Scripps Institution of Oceanography in La Jolla, Calif.Smaller snowpacksRecent studies project that the heat will cause smaller snowpacks across the West. Cayan and U.S. Geological Survey researcher Noah Knowles concluded that a temperature increase of about 4 degrees Fahrenheit would reduce the Sierra Nevada snowpack by a third by 2060, primarily at lower elevations, and halve it by 2090.Dams can hold back some of the runoff. They already do. However, in the Cascade mountains of Oregon and Washington, artificial reservoirs store only about 10 percent of the annual flow. California has more storage, but not enough, given this drier, hotter future.Colorado has a different story. It has more dams to hold back the spring snowmelt, and it also has more rain in summer. Still, if global warming causes more rain and less snow, that will make the existing water infrastructure less functional, says the river district’s Kuhn.The reduced snowpack forecast for the Rocky Mountains is less than on the West Coast, but one study foresees 30 percent less snow. And while the pace of runoff in Colorado lags that of the West Coast, runoff can be expected to be four weeks earlier within 50 to 90 years, says Kevin Trenberth, who heads the climate change analysis unit at the National Center for Atmospheric Research in Boulder. All of this has water managers thinking more dams for Colorado. “My attitude at this juncture is there is no such thing as too much storage,” says Porzak, whose clients include Vail Resorts.At the river district in Glenwood, Kuhn agrees, but he also notes that not all dam sites are equal. At Hoover Dam, Lake Mead loses about one million acre-feet of water each year from evaporation, and Powell loses about half that much. That’s more than a quarter of the water in the river in a drought year.”The question is do we have the storage buckets in the right places,” says Kuhn. “My view is that you will see additional storage, but not necessarily large main-stem storage that evaporates.”Hotter means drier
For Gerald Meehl, a senior scientist at Boulder’s NCAR, this climate of the future is professional and personal. He was among the 120 scientists who wrote the 2001 report issued by the International Panel on Climate Change that reported a strong consensus among scientists that the fingerprints of man had become the dominant influence on climate change.Meehl was reared on a dryland farm near Hudson, about 30 miles northeast of Denver. There, the winter wheat crop depends entirely upon natural precipitation, not irrigation. Even now, wheat farming is a crap shoot, and in the future the odds will worsen.”The global models for quite a number of years have always projected that there would be a tendency toward drier conditions in the summer in the mid-continental regions, which would include Colorado,” he explains. “This is due to warmer temperatures.”In other words, even if thundershowers are as frequent 30 years from now, the soil will be drier, because of warmer temperatures. That does not bode well for wheat or other crops in Colorado.Of course, that’s just the probability. Meehl long ago left the farm, but he still has relatives who are tied to the soil. Like most of us, they are interested less in long-term climate shifts than in next year’s weather.”My farmer uncles always make fun of me, because they ask what will happen next winter, and I always will give them a certain range of uncertainty,” reports Meehl. “They say, ‘You guys never give a straight answer.’ “Attention of farmersBut the odds are high enough that climate change has the attention not only of academics and environmentalists, but also more mainstream groups such as the Rocky Mountain Farmers Union.John Stencel, president of the organization, which has 23,000 families in Colorado, Wyoming and New Mexico, says many older members who can remember droughts as far back as the 1930s believe something new and different is now occurring. “They say that weather fluctuations are greater, more severe,” he reports.Are man-caused greenhouse gases to blame? Rank-and-file members are not necessarily persuaded of the connection, but Stencel is. “There has to be something to what a lot of scientists are saying,” he says.Vail, Colorado