A wet fall in the Upper Basin may have postponed a shortage declaration for another year, but a shortage during the next decade is looking more and more likely.
Once again, we consider the possibility of a Colorado River shortage declaration. With shortage conditions looming, we’ll return to this topic periodically throughout 2014.
In December, Reclamation released its 2014 Annual Operating Plan for the Colorado River system. Required by statute, this report is receiving more attention than usual because the system is now teetering on the brink of an official shortage. River flows have been below average in 11 of the past 14 years; in addition, the two consecutive years with lowest recorded inflow in the last century were 2012 and 2013. Storage volumes in Lake Powell and Lake Mead are less than 50 percent of capacity. Further exacerbating the situation for downstream users will be this year’s reduced releases from Lake Powell into Lake Mead. As a result, the question of shortage has shifted from “What if?” to “When?”
Under the 2007 Interim Guidelines, 2014 releases from Lake Powell will be reduced from the usual 8.23 to 7.48 MAF — for the first time — because of dropping reservoir conditions. The Guidelines specify protocols for declaring a shortage based on Lake Mead elevations forecasted for January 1*. According to the Guidelines, if the lake is projected to drop below 1,075 feet, a Lower Basin shortage will be declared and deliveries will be reduced. Last August’s projections for January 1 show the lake remaining above 1,075 feet in 2014, with a 50 percent probability of shortage in 2015. Thanks in large part to a wet fall in the Upper Basin that boosted projected inflow to 94 percent of average, the possibility of a shortage has now dropped to only 2 percent for 2015. However, we’ve only kicked the can down the road 1 year: Reclamation’s current modeling now puts the chance for a shortage declaration in 2016 at 50 percent.
A shortage declaration will reduce water deliveries to Arizona by 11.4 percent (320,000 AF/yr) and to Nevada by 4.3 percent (to 13,000 AF/yr). In the short term, these reductions will not impact deliveries of municipal water supplies, and both states have invested millions on contingency plans for maintaining deliveries during shortages for the next several decades. Nonetheless, deeper and more prolonged cuts are all but inevitable later this century; these factors must be a part of long-term planning and investment.
* These forecasts are presented in the 24-Month Study that is released in August of the previous year.