LAS VEGAS — Arizona would be the first state to feel the effects of Colorado River cutbacks if the water level continues to fall at drought-stricken Lake Mead, an environmental advocacy group says in a new report.
The Western Resource Advocates reached its conclusion as the vast reservoir behind Hoover Dam sits at 39 percent of capacity.
The group concluded that farmers would be first to feel the pinch; that suburban growth in Phoenix and Tucson could be slowed by cutbacks; and the cities themselves could face water reductions by 2020.
“These cuts are looming because Arizona’s ‘bank’ for 40 percent of its water supply, Lake Mead, is being drained faster than it can be filled,” said the report titled “Arizona’s Water Future: Colorado River Shortage, Innovative Solutions, and Living Well with Less.”
“Lake Mead has this growing bathtub ring, even though everyone is using their legal amounts of water,” said Drew Beckwith, an executive with the organization.
Central Arizona Project official Chuck Cullom said water managers have known for years that more river water is promised to users than enters the system — even in non-drought years. He said Arizona is not alone.
The Colorado River brings Rocky Mountain snowmelt from headwaters in Wyoming, Colorado, Utah and New Mexico downstream to Arizona, Nevada, California and Mexico.
“There is a structural deficit that poses risk to all water users,” Cullom said.
But he added that “current projections show it’s highly unlikely that we would affect municipal supplies in this decade.”
The report release came the same week that outgoing Interior Secretary Sally Jewell warned that key drought contingency plans aimed at reducing the risk of water shortages in seven Western states remain unfinished as a new U.S. president takes office.
One issue involves a binational share-the-pain pact reached in November 2012 with Mexico that is set to expire. It lets Mexico store water in Lake Mead, which helps keep the lake above a trigger point where the U.S. Bureau of Reclamation would cut water deliveries to Arizona and Nevada.
The lake level on Friday was 8 feet above the line — down about 130 feet since 2000. The lake was last at full capacity in 1983.
Lake Mead is the biggest reservoir in the system that irrigates Southern California crops and provides drinking water to some 40 million people.
Federal water managers say it’ll take a lot more snow and rain than parts of the West have seen in recent weeks to make a dent in the drought.
“Even if we have a good water year like we did in 2011, that doesn’t undo 16 years of drought,” said Rose Davis, a Bureau of Reclamation spokeswoman in Nevada.
In 2011, the river flow into the Lake Powell reservoir east of the Grand Canyon was 47 percent above normal, Davis said. Projections this year, so far, are for a 12 percent bump.
The bureau says there’s still about a 50-50 chance that a water shortage declaration will be made in August to trigger cuts in supplies to Arizona and Nevada in January 2018.
Arizona could lose 11 percent of its annual allotment, and Nevada could lose about 4 percent. The amount of water at stake could, combined, serve more than 625,000 homes. But deliveries to farms in Arizona would be affected first.
Nevada water managers say the effect would be felt less in and around Las Vegas, which draws 90 percent of its water from Lake Mead, because conservation and reuse programs have in recent years cut the amount of water the area uses.
Western Resource Advocates said it reached its conclusions after crunching data from the Arizona Department of Water Resources and Central Arizona Project.