Reservoirs are water savings accounts. Largely, they operate to catch snowmelt for use later in the summer–but are big enough to build a nest egg for future drought years.
If you like to brush your teeth, shower, eat and water your lawn, you are a water user, dependent on this system so necessary in arid Colorado.
So how are the reservoirs holding up in this drought year? They are working as planned, but water levels are being drawn down. Green Mountain Reservoir is currently about half full, well below the August average. Clearly it is going to need a good snow year this winter.
Lake Powell, located in northern Arizona and southern Utah, is Colorado's biggest water-savings account, helping Colorado, Wyoming, New Mexico and Utah meet obligations under the Colorado River Compact of 1922. More on that in a moment.
First, Powell is a good indicator of drought on a regional basis. Currently, it is at 70 percent of its August average but 58 percent of capacity. It could have been worse except for the outstanding snow year in 2010-11. But this past runoff season was abysmal. The April-July inflow was 2.06 million acre-feet (29 percent of average), making it the third driest on record since the closure of Glen Canyon Dam in 1963, the Bureau of Reclamation reports. Only 1977 and 2002 had lower same-period inflows. So no savings accrued this year.
Local reservoir conditions have much to do with how water utilities establish outdoor water-use rules and how ranchers and farmers cooperate to get by on what's available. So it bears watching how Green Mountain, Dillon and other "buckets" in Colorado fare for the rest of the year. Have water providers and water users done enough to stave off more drastic water restrictions next year? By next March, we are likely to know.
But Lake Powell is the big game. Its long-term health will determine in future decades whether Colorado and the other states just mentioned have to curtail water use in order to keep required flows heading to Arizona, California and Nevada. In 1922, when negotiators from the seven states divided the river for human use, the Lower Basin States got the better half. They get theirs before we get ours. Powell has made sure that this day of reckoning has never come, and hopefully never will.
But we need more than hope. That's why the Colorado River District and many of its constituents in Western Colorado are discussing risk management when it comes to future water development projects such as the Flaming Gorge pumpback, for example. Water providers on the Front Range are also engaged. Nobody knows for sure where we cross the line of developing too much water and forcing a curtailment on the Colorado River system that nobody wants, no matter which side of the Continental Divide. The Front Range has a big stake. Colorado River water in amounts between 450,000 and 600,000 acre-feet goes to the east in any given year, depending on conditions. Those transmountain flows are taken under water rights that would be subject to compact curtailment.
Risk management means trying to understand steps that can be taken to right-size a project or even forestall a project until more information is known about water supply and climate change. It is being incorporated into "scenario planning," a process of figuring out a range of possible futures and strategies that meet those futures. These concepts are under study by the Colorado Water Conservation Board, nine basin roundtables and the Interbasin Compact Committee, the latter two formed in 2005 under the Colorado Water for the 21st Century Act.
Gov. Hickenlooper has asked these entities to come up with a statewide water plan by 2016, to address water supply for a population that could double to 10 million people by 2050. So while we think short term about drought, reservoir levels and more powder days (yeah!), keep an eye on Powell and the larger issues it represents.
This is part of a series of articles coordinated by the Water Center at Colorado Mesa University in cooperation with the Colorado and Gunnison Basin Roundtables to raise awareness about water needs, uses and policies in our region. To learn more about the basin roundtables and statewide water planning and let the roundtables know what you think, go to www.coloradomesa.edu/WaterCenter.blog comments powered by Disqus