From the Grand Junction Free Press (Hannah Holm):
The Colorado River Basin Water Supply and Demand Study, released by the Bureau Wednesday, Dec. 12, projects that these demands will continue to grow, even as climate change models indicate that average annual inflows to the basin from rain and snow are likely to diminish. The fact that water use has already exceeded inflows into the basin for nearly a decade, while the region has been in drought, shows just how close to the margin we are already. The giant reservoirs of Lake Powell and Lake Mead can only enable overuse of the river for a limited amount of time.
The Bureau’s study, conducted with input from numerous water managers and interest groups and drawing on historical observations, studies of ancient tree rings and global climate change models, began by defining four plausible future water supply scenarios and six demand scenarios. Interim reports on these scenarios have been out for months, and they don’t paint a pretty picture.
Comparing the median of water supply projections against the median of demand projections (without any action to change how water is managed) yields a projected imbalance of 3.2 million acre feet/year by 2060. That’s 3.2 million football fields covered with water one foot deep. An acre foot is about enough to supply two average families of four for a year, under current use patterns. 3.2 million acre feet is a lot of water to want but not get.
The new parts of the Bureau’s study focus on what can be done to avoid that bleak future. For this, the Bureau asked for input from all interested parties. They got about 150 suggestions, ranging from towing icebergs to California to conservation and reuse strategies.
The study evaluated a representative range of all the suggestions it received based on their feasibility, viability, how much water they could generate or save, environmental impacts and other factors. These were then grouped into portfolios reflecting different strategies (try everything, maximize reliability, minimize environmental impacts, etc.), and the portfolios were evaluated to see how well they would work to resolve future supply and demand imbalances.
The results of these evaluations show that all of the portfolios significantly reduce the number of years in which the basin would be vulnerable to hitting key indicators of supply and demand imbalances, such as critically low water levels in Lake Mead, low flows below Lake Powell, and failure to maintain target flows for healthy rivers and recreational boating. However, the study points out that even if every measure studied is taken, “plausible futures still exist in which the system is vulnerable.” Put more directly, “complete elimination of Basin vulnerability is not likely attainable.”