The agency that typically provides Southern California with about half its water supply tightened the spigot Tuesday when its board voted to cut regional deliveries by 15%.

The move by the Metropolitan Water District of Southern California increases pressure on Southland residents to further curb water use in the fourth year of one of the worst droughts on record. It follows Gov. Jerry Brown’s unprecedented order directing Californians to slash urban water use by 25% compared with 2013 levels.

Intended to reduce Metropolitan’s overall deliveries by 15%, the cuts will take the form of allocations to the 26 cities and water districts that MWD supplies with water from Northern California and the Colorado River. Agencies that exceed their allocations will have to pay punitive surcharges on the extra water, a cost they will try to avoid by strengthening local conservation measures.

The delivery cut, which will take effect July 1, marks only the fourth time Metropolitan has trimmed wholesale supplies for its member agencies, which in turn sell water to the hundreds of local water districts that supply residential and commercial customers throughout the urban Southland.


A 15% drop in deliveries would conserve about 300,000 acre-feet of water, slowing the drawdown of Metropolitan’s dwindling reserves. One acre-foot of water is nearly 326,000 gallons, or enough to supply two households for one year.

MWD began the drought in 2012 with record amounts of water stored in groundwater banks and regional reservoirs. But to meet demand as the drought forced the state to slash Northern California water shipments, Metropolitan has steadily drawn on its savings account. This summer, staff projects reserves will have fallen from 2.7 million acre-feet to slightly more than 1 million acre-feet.

The staff recommended a 15% reduction, which a board committee approved Monday despite arguments by some members that a 20% cut was necessary to avoid depleting reserves to dangerous levels.

Metropolitan has trimmed deliveries several times in previous droughts -- 10% in 1977, 17% in 1991 and 10% in 2009-10. In each instance, MWD’s member agencies have reined in use enough to avoid financial penalties.


But officials predict it will be tougher this time to attain the necessary water savings to avoid surcharges, given that many Southland cities have significantly reduced their use in recent years.

“It’s going to be a real challenge,” board member Don Calkins of Anaheim said Monday.

In addition to reserves, Metropolitan is expecting full deliveries from the Colorado River this year and will get 20% of its requested amounts from the State Water Project, compared with 5% last year. The agency also is ramping up a long-term program under which growers in the Palo Verde Irrigation District in southeast California idle land and sell the conserved water to Metropolitan.

But Metropolitan’s plans to buy as much as 100,000 acre-feet of water from Northern California farmers have been frustrated by a lack of sellers, forcing MWD to shop for supplies in the Colorado River basin.


Jeffrey Kightlinger, MWD’s general manager, said the staff will review water demand and supply every month. As part of Tuesday’s vote, the board also said it would review water supply conditions in December to see if adjustment to the allocation was necessary.

bettina.boxall@latimes.com

Twitter: @boxall