The federal Bureau of Reclamation has completed its crucial August 2017 24-Month Study, which is part of a study of hydrology and projected operations of the Colorado River system. Results depict water flows slightly improved from recent years, enough to assure that Lake Mead will avoid a “shortage declaration” for 2018, at least.
The August projections, which are used by the Bureau (or, BOR) and the Lower Basin States to determine whether the threatened reservoir may fall to levels that could trigger a shortage declaration, anticipate Lake Mead to be at an elevation of 1,083.46 feet at the end of the calendar year.
That would put Lake Mead levels more than eight feet above the 1,075-foot mark. Under 1,075 feet, Arizona and Nevada begin taking delivery shortfalls according to terms set out in a 2007 agreement.
The improved hydrology also further decreases the likelihood of a 2019 shortfall declaration on Lake Mead, which according to the Bureau stood at 31 percent as recently as April.
While weather is variable and never entirely predictable, the trend line is positive. A year ago, the BOR was projecting that the chances of Lake Mead falling into shortfall as soon as January 1, 2018 stood at even odds. An unusually snowy early winter that blanketed the western slopes of the Rocky Mountains substantially brightened that outlook, however.
Arizona Department of Water Resources Director Tom Buschatzke credited conservation efforts enacted beginning in 2014 for making the difference at Lake Mead.
“The collective efforts of Arizona, California, Nevada and Mexico to conserve water in Lake Mead from 2014 through 2017 have created an additional 14 feet of elevation in the lake,” said Buschatzke.
Taken together, the conservation efforts left almost 1.2 million acre-feet of water in the reservoir.
“Absent those proactive actions to conserve water in the lake, the projected January 1, 2018 lake elevation would be at about 1,069 feet. These actions have clearly kept us out of shortage,” he said.
“This ‘all hands on deck’ approach is the key to successfully managing the Colorado River,” said the ADWR director.
A “Tier 1” shortage declaration would cost Arizona about 11 percent of its 2.8 million acre-foot Colorado River allocation.
This year alone, a combined 465,000 acre-feet left in Lake Mead by the Metropolitan Water District of Southern California (200,000 acre-feet), the Gila River Indian Community (80,000 acre-feet) and the Central Arizona Project (185,000 acre-feet) have added over five feet to Lake Mead’s water levels.
The August 24-Month Study projections for anticipated elevations on the last day of calendar the year are used by the Secretary of the Interior to set the operating tiers for Lake Powell and Lake Mead.
The projection also is used to determine whether or not a shortage will be declared in the Lower Basin.
While the results of the BOR’s August study are positive for the system, they also indicate the volatility of moisture levels in the Colorado River watershed and the challenges of making accurate predictions.
As recently as last March, some analysts were talking openly of the possibility of a huge “equalization” release of water this year from Lake Powell to Lake Mead – the result of a winter snowpack that, to that point, had been extraordinary.
Some predicted an 11 million acre-foot release from Powell, enough water to raise surface levels at the troubled reservoir downstream by as much as 27 feet.
A late-winter hot-and-dry spell, however, put an end to those giddy expectations.
“Arizona is committed to continuing conservation efforts to bolster the elevations of Lake Mead to avert shortages,” said Buschatzke.
“We are confident that our neighboring states and Mexico will also continue their efforts to conserve water."