As Lake Mead Dwindles, Arizona and Other Colorado River Basin States Continue to Plan for a Drier Future

It has become a familiar refrain.  For each of the past three years, the United States Bureau of Reclamation, which operates the major reservoirs on the Colorado River, has announced a new “record low” water elevation in Lake Mead.  A quick Google search identifies articles or posts discussing this downward trend in September 2014, June 2015, and May 2016.  The now familiar “bathtub ring” on the shores of Lake Mead dramatically illustrates the effects of these lower water levels, dwarfing even larger boats on the Lake.

For Arizona and the rest of the Colorado River Basin, this is serious business.  Lake Mead is the major reservoir for storing and delivering Colorado River water to the “Lower Basin” states of Arizona, California, and Nevada.  Millions of residents in these states depend on this water supply.  When full, Lake Mead can hold 26 million acre-feet of water, or more than three years of normal supply for the Lower Basin.  Unfortunately, the Lake has not been completely full for more than thirty years, and since 1999, when it was at 95% of capacity, water levels in the Lake have fallen in an almost uninterrupted path to its current 37% of capacity.  If the Lake drops much farther, the Bureau of Reclamation will be forced to declare the first official shortage on the Colorado River.  In fact, if not for the “Miracle May” of 2015, when the Colorado River Basin received far greater than normal precipitation, a shortage declaration might already have been made for the 2016 water year.

There has been no Miracle May this year.  Current estimates project that total runoff for the watershed will be 84% of the historical average—certainly not enough to dig us out of the hole we find ourselves in after 16 years of drought.  Nevertheless, the Bureau of Reclamation currently projects only a 10% chance that a shortage will be declared for 2017.  This number, however, rises above 50% for 2018 and to more than 60% in 2019 and beyond.

Fortunately, Arizona and the other Basin states have not been sitting idly by while awaiting their fates.  Instead, they have been actively planning for the possibility of shortage on the River, and even now are engaged in discussions to identify ways that, through shared efforts and sacrifice, water levels in Lake Mead can be boosted to protect the Lake as a critical component of the Lower Basin’s water supply.

Arizona in particular has been a leader in these efforts.  Since the 1990s, when the Arizona Water Banking Authority was created by the Arizona Legislature, the Authority has stored more than 3.4 million acre-feet of Colorado River water in the groundwater basins of central Arizona.  Combined with the efforts of other entities in Arizona, more than 9 million acre-feet of water have been stored overall.  This water will provide a critical backup supply for Arizona whenever a shortage is declared on the Colorado River.

More recently, Arizona has collaborated with other Basin states (as well as Mexico) in a number of voluntary reservoir protection efforts designed to keep extra water in Lake Mead.  These efforts are intended to conserve a total of 740,000 acre-feet of water from 2014 through 2017, including contributions by water delivery entities in Arizona, California, and Nevada, as well as the Bureau of Reclamation.  These efforts have already helped boost water levels in Lake Mead to the point where a shortage declaration for 2017 is unlikely.  However, more must be done to ensure the long-term viability of Lake Mead as a water supply for the Lower Basin.

To that end, Arizona has been participating in discussions with other Basin states and the Bureau of Reclamation to develop a longer-term “Drought Contingency Plan” that would involve Arizona agreeing to take steeper cuts in its annual Colorado River allocation than are required under the current interim shortage sharing guidelines adopted in 2007.  In return, other states would also agree to take greater-than-required decreases, with the overall effect being more water left in Lake Mead to protect against a continued downward spiral that could otherwise result in the Lake reaching a “deadpool” elevation where no water could be effectively distributed to any of the Lower Basin states.

If Arizona agrees to take greater-than-required cuts in its Colorado River water supply, there will be ramifications for a broad swath of Arizona water users.  The Arizona Department of Water Resources and interested parties continue to discuss how best to manage these impacts.  The discussions with other Basin states are likely to continue for much of the rest of this year.  Given the long-term implications for Arizona—whether under the current 2007 interim guidelines or under a new Drought Contingency Plan if negotiations with other states in the Basin are successful—these efforts should be carefully watched.  Our water future may depend on their success.