Looking up at the Grand Mesa from Grand Junction in early April, it was good to see snow on its flanks. For too much of this past winter, they have been bare. Skiers felt the pain of the dry winter early; fish and ranchers will feel it this summer.
Here, the impacts of this year's drought will likely be eased by last year's bounty, stored in reservoirs upstream. More troubling are the dry conditions we've been seeing since 2000. In a report released in March, the Colorado River Research Group warns that we may be undergoing a process of aridification, rather than a drought. If this is the case, current drought planning efforts could really be the first step in a longer-term process of adaptation.
The research group points to studies showing that warmer temperatures have already led to a larger portion of our snowpack evaporating or getting taken up by plants before it has a chance to reach streams. 2017 was a case in point, with a very large snowpack converted into only moderately above-average inflows into Lake Powell.
Water managers and policy makers have not failed to notice this drying trend, reflected in dropping levels in Lakes Powell and Mead. Water users in Arizona, California and Nevada have reined in their water use a bit, managing to keep Lake Mead just barely above official shortage levels. Upstream, in Wyoming, Utah, New Mexico and Colorado, water leaders have been conducting modeling exercises to assess the risk of critical shortages and experiments to test options for responding.
The Colorado River Risk Study spearheaded by the Colorado River District and the Southwestern Water Conservation District has modeled several scenarios to assess the risk of Lake Powell dropping too low to reliably generate hydropower or meet downstream obligations under the 1922 Colorado River Compact. If that happens, cities could rush to purchase water rights from farms, potentially drying up much of the agriculture on the Western Slope.
Using historical hydrology from 1988-2012 and demand numbers that roughly track current use trends, modeling indicates a 20-percent chance of Powell dropping into the danger zone between now and 2036 if we don't significantly change how water is managed. Using the same demand and hydrology data, that risk could be cut in half if major reservoirs like Blue Mesa and Flaming Gorge release extra water to Powell and the lower basin states implement their own plans to protect Lake Mead levels. The risk drops further if conservation generates water that could be stored in a "bank" and released as needed. However, major benefits would come only after such a bank has had time to build up significant reserves.
Meanwhile, the Upper Colorado River Commission has been testing whether paying water users to temporarily reduce their use could help prop up Lake Powell water levels. Temporary reductions, rotated between water users, are an alternative to the permanent "buy and dry" of agricultural water rights. Participants in the grant program include the Grand Valley Water Users Association, which chose several farmers by lottery to temporarily fallow their land, and farmers in the North Fork and Uncompahgre Valleys who reduced irrigation or grew alternative crops.
The commission's report on the program concluded that it could work if several hurdles are overcome. It is unclear if legal tools currently exist to ensure that water conserved by one user could make it to Powell without being taken by someone else along the way. Measuring water saved through modified irrigation practices is also challenging. And the cost could be high — at rates used by the program in 2017, it would cost $40 million to conserve about 200,000 acre feet of water.
In Western Slope discussions about drought planning, participants have expressed a strong desire to ensure that cities share the pain of any use cuts with farmers. There is also concern that proactive conservation could facilitate new drains on the Colorado River system, rather than protect existing uses.
The data clearly demonstrate that we face the risk of a drier future. There are ways to mitigate the impact on our communities, but they are likely to be expensive and will certainly be complicated. This enhances the urgency of pressing forward now. The sooner we can find equitable, feasible mechanisms for adapting to drier conditions, the more smoothly we will be able to handle both temporary droughts and drier conditions over the long term.
Hannah Holm coordinates the Hutchins Water Center at Colorado Mesa University, which promotes research, education and dialogue to address the water issues facing the Upper Colorado River Basin. Support for Hutchins Water Center articles is provided by a grant from the Walton Family Foundation. You can learn more about the center at http://www.coloradomesa.edu/water-center.
