SAN DIEGO — With an ominous deadline approaching, two feuding Imperial Valley agencies have put aside their differences and developed a plan they hope can save the ailing Salton Sea, the state's largest body of water and often considered its most vexing environmental problem.

The Imperial Irrigation District and the Imperial County Board of Supervisors have agreed to push for additional geothermal energy exploration on the eastern edge of the sea.

The goal is to raise money for restoration projects from the profits from energy sales. Officials also want the geothermal companies — and the utility agencies that buy the electricity — to take care of Salton Sea property that is now underwater but may soon be open to the air.

A sense of urgency comes from the fact that after 2017, under its water sales agreement with the San Diego County Water Authority, the Imperial Irrigation District will no longer send water directly into the sea.

Without that water, the shallow, salty, tea-colored sea will recede further, exposing more sea bottom — worsening the sea's noxious smell as well as dust storms that plague the Coachella and Imperial valleys.

After 2017, "the Salton Sea falls off a cliff environmentally," said Kevin Kelley, the general manager of the Imperial Irrigation District.

"This is our best hope," said Ralph Cordova, chief executive officer of Imperial County.

There are daunting obstacles.

Salton Sea restoration projects are estimated to cost billions of dollars, although there are plans to scale down any projects. Anything involving water and energy in California is enormously complex — technically, legally and politically — and the sea, located in a lightly populated area, does not appear to have much of a political constituency in Sacramento.

Still, decision-makers in Sacramento are talking about the plan.

"Anything that helps the state expand its renewable energy, I'm very supportive of," said Michael Peevey, president of the California Public Utilities Commission. "We need all the resources we can develop out there in the Imperial Valley."

Karen Douglas, a commissioner with the California Energy Commission, recently went kayaking on the Salton Sea. "The renewable energy potential is there and it's real," she said. "But there is a lot of analysis and work to translate that potential into reality."

Geothermal energy production can involve drilling wells to tap into the Earth's heat and water. Once that heated water is brought to the surface, it can be used to power turbines that produce electricity. Imperial Valley is considered to have one of the nation's largest geothermal reservoirs.

Making the plan a reality would require a transmission line to get the energy to the grid.

The California Natural Resources Agency is preparing a report on the Salton Sea, with a deadline set for May 2016. The report will include information that could "inform the decision-making processes" at the California Independent System Operator, the nonprofit group that oversees the state's electricity system and its transmission lines.

In hopes of gathering more support, Kelley last week talked to his peers at the Los Angeles convention of the Assn. of California Water Agencies.

"The Salton Sea should be given great consideration," particularly with the energy loss from the shutdown of the San Onofre nuclear plant, Kelley said.

The Salton Sea was created when the Colorado River jumped its banks in 1905 and gushed into an ancient salt sink straddling Riverside and Imperial counties. Its major sources of replenishment are the noxious New River flowing from Mexicali, Mexico, and pesticide-laden agricultural runoff.

To sell water to San Diego, the Imperial Irrigation District agreed in 2003 to use less of its massive share of the Colorado River. Less water for irrigation means less runoff and a shrinking Salton Sea.

The irrigation district has estimated that 50,000 acres of sea bottom, full of sediment and small-grain particles, would soon be exposed to the air and wind.