The Metropolitan Water District of Southern California on Tuesday approved a plan for sharing Colorado River delivery cuts if a shortage is declared on the drought-depleted river.
The vote by the district, which imports water to the Southland, represents another step in a years-long attempt to forge a shortage agreement among the seven states that depend on the Colorado for drinking and irrigation supplies.
Several other agencies, as well as the state of Arizona, still have to adopt the plan, making it unlikely that the pact will be finalized this year.
Under the proposal, Metropolitan and other California districts would reduce their diversions earlier in a shortage than they would if the lower-basin states strictly followed established water rights.
California’s share of the Colorado is the largest among all seven basin states — 4.4 million acre-feet, or more than a quarter of the river’s average annual flow.
Most of the state’s diversions go to the Imperial Irrigation District and other farm districts in California’s southeast corner, which have yet to take final votes on the proposal.
Metropolitan has been importing river water since the 1940s, and the Colorado remains an important source for urban Southern California.
For decades Metropolitan benefited from river surpluses that allowed the agency to use far more than its base allocation of 550,000 acre-feet. When the surpluses dried up, it struck a series of deals with farm districts that fallow cropland and sell unused supplies to Metropolitan.
Under the proposed drought contingency plan, Arizona and Nevada would absorb the first cuts and California would reduce its withdrawals from Lake Mead when the reservoir’s elevation drops to 1,045 feet.
Metropolitan would essentially be banking some of its allocation in Mead to avert more severe rationing if the huge reservoir declined to dangerous levels.
The nearly two-decade drought in the Colorado basin has cut total river storage roughly in half. Federal water managers have warned since the early 2000s that they may have to formally declare a shortage, triggering mandatory delivery cuts.
Even without the drought, states have to deal with the fact that the river is over-allocated.
The river’s flows were divvied up in the early 20th century — an unusually wet period that presented a misleading picture of what the Colorado could produce year in and year out.
The U.S. Bureau of Reclamation has said a shortage could be declared in 2020. But if this turns out to be a snowy winter in the upper basin, the West could once again win a reprieve.
Federal officials have pressured the states to wrap up the drought plan this year. But disputes among Arizona water agencies about how that state would carry out the cuts have slowed approvals.
“Arizona is the one that is still negotiating,” said Jeffrey Kightlinger, Metropolitan’s general manager.
Along with Imperial, two smaller districts in California have to take final action.
Because the plan calls for changes in reservoir operations, Kightlinger said, the states will also seek congressional approval.