The Colorado River Basin provides water for seven states and almost 40 million people, but between rising populations and climate change, it will not be able to do so forever. Last Thursday, the Bureau of Reclamation released a much-awaited report on water supply in the Colorado River Basin that indicated the need to prepare for even more water shortages in the region. The report’s median projections predict a gap between water supply and demand of 3.2 million-acre-feet by 2060 — that’s about five times the amount of water that Los Angeles uses in a year. (A million-acre-foot is the volume of water it would take to cover an acre one foot deep, a million times.)
Droughts are much less flashy realizations of climate change than catastrophic storms. While they rarely grab news headlines, preparing for them is a vital part of any climate mitigation plan. Recent studies suggest that Colorado River flows will decrease by anywhere from 6 to 20% by the year 2050. The Reclamation report, for its climate change projections, assumed a reduction in river flow of only 8.7%. This is no small reduction, at a staggering 1.3 million-acre-feet, but my hunch is that it is optimistic. Growing populations in central Arizona, the Colorado front ranges and Los Angeles will collide with lower river flow to result in worse water shortages in the coming decades, in an area already accustomed to prolonged droughts.
Making up for this water shortfall is vital. 15% of the nation’s crops and 13% of its livestock depend on Colorado water. Water shortages can affect electricity production, too. Droughts have resulted in 16% lower electricity production at the Hoover dam over the last 12 years, and if levels drop too low the dam will have to shut down entirely. Keeping water levels high is also important for the $26 billion water sports industry, as well as the millions of people who depend on it every day.
The Bureau report indicates several categories of adaptation approaches to deal with the impending water shortages. The good news is that they conclude it will be possible to close the gap, but the bad news is that it will be incredibly costly.
Adaptation measures fall into three general categories: importing water from elsewhere, desalination, and conservation through efficiency and reuse. There is already a $150 million desalination plant at Yuma, Arizona, but it is aging and very costly to run. Importing water is also costly; more extreme suggestions include a pipeline from the Missouri River to Denver that would cost billions of dollars. Conservation can cut water demand by large fractions, especially for residential uses, particularly since the recycling of “grey water” has been increasing in popularity. Some combination of all of these categories is likely to be necessary, and any combination will be pricey.
This news is nothing new. Water utilities in the Southwest have already been investing in increasingly costly infrastructure to cope with lower reservoir levels. A trade group report back in 2009 predicted that water utilities would have to spend somewhere between $488 billion to $944 billion between now and 2050 to adapt to water shortages arising from our shifting climate.
Remember that when people argue that fighting climate change would be too costly — adapting to it could be even costlier.