Below Average, But Not Too Far Below Average Te Colorado River water delivery system relies on storage – about 60 million acre-feet of water between the Upper Basin and the Lower Basin with about 50 million acre-feet of that from Lake Powell and Lake Mead. “It’s really the storage in the system that helps us to operate under such a tight margin from year to year,” Daniel Bunk, lead hydrologist with Reclama- tion’s Lower Colorado Region Office, said at the drought briefing. About 90 percent of the inflow into


the reservoirs comes from the Upper Basin “so we really rely on the snowpack for water supply,” Bunk said. Te driest 16-year stretch on record has left quite an impact, dropping Lake Mead’s water level by 140 feet, the lowest since it initially filled in the 1930s. Te lake is projected to slowly recover to about 1,078.5 feet above sea level by the end of 2016. Te 1,075-foot elevation is the first tier for cuts in water deliveries. Bunk said “there is still a slight


chance” of a Lower Basin shortage con- dition in 2017 and “a more significant chance” by 2018. Te forecasted 2016 inflow of 92 percent of average would make it the 14th year of below aver- age inflow “but at least not as far below average as we have seen previously,” he said. As a result, Lake Mead will decline by about 4 feet this year, which is not as much as a typical year in the drought where it declines as much as 14 feet. “Tere is still a strong likelihood of not being in shortage and being a normal condition in 2017 but if you look out towards the end of 2017 and what it means for 2018, there is a lot less certainty,” Bunk said. Te shortage guidelines have equal-


ization provisions for Lake Powell and Lake Mead plus mechanisms for water forbearance, intentionally created surpluses and shortage sharing. In 2012 the United States and Mexico adopted Minute 319 to the 1944 U.S.-Mexico Treaty that outlined shortage and


Te Colorado River Basin.


surplus sharing and water conservation measures between the two countries through 2017. “Between these programs there is


approximately 6 feet of water in Lake Mead to slow the decline,” Bunk said.


‘Newly Defined Flexibility’ Arizona is entitled to a 2.8 million acre- feet allocation of the Colorado River each year. It also is the junior water rights holder in comparison to California and state officials recognize what could happen in the event of a shortage declaration.


“We are prepared, as we must be as the junior priority holder on the Colorado River, for shortage if and when it happens,” said CAP’s Cooke at the briefing. “As we get closer to that, the more grateful we are that we are prepared but there is still more work to do both to capitalize on what we’ve done already and additional steps to continue to do what we’ve always done.” Lake Powell on the Arizona-Utah


border fills each year as snowmelt from the Rockies peaks in early summer. Water released from Lake Powell flows


Summer 2016 • River Report • Colorado River Project • 5


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