For California, which has endured four years of extraordinary drought, the state's wet season is off to an encouraging start.

High in California's Sierra Nevada, the state's mountainous spine, El Niño-driven storms have piled snow and the meltwater it represents to near-normal levels. At lower elevations, heavy rains are nudging the water in many depleted reservoirs back toward their historical averages.

Whether this spells the beginning of the end to what some researchers have tagged as the state's worst drought in at least 1,200 years remains to be seen. The state still faces a significant, long-term precipitation deficit. What is clear is that the drought has accelerated the onset of a “new era” of water use in the Golden State, some water-policy specialists say.

Conservation continues to play a vital role. But it's also an era where the hunt for sustainable water sources increasingly focuses on finding ways to husband local supplies, rather than tapping ever more distant ones.

Some urban areas, such as San Diego, are turning to the Pacific Ocean and desalination to help ensure supplies. Others, such as Los Angeles, are forgoing desalination, at least for now. Instead, they are placing a heavier emphasis on various forms of water recycling, as well as capturing rainfall to recharge groundwater supplies.

The changes are taking place not only in response to the state's history of recurring droughts. They also are occurring in anticipation of the additional stress climate change is expected to bring to California's water resources.

For a state with a tumultuous water history, the transition in water management is significant, specialists say.

“As late as the early 1980s, which isn’t very long ago in the water world, the belief was that you would just go to the next river” to meet growing water needs, says Jonas Minton, water-policy adviser to the Planning and Conservation League, an environmental group based in Sacramento, Calif.

“Now we appreciate that there are not more rivers to go to,” says Mr. Minton, who also has served as a county water manager and later as deputy director of the state's Department of Water Resources. “You can’t just sink more groundwater wells, because that’s a decreasing source of supply. So you have to better manage what you have.”

California is no stranger to drought, a fixture of its Mediterranean climate. But it took an intense, two-year drought in the late 1970s to trigger widespread efforts to conserve water.

As a result of that and other measures, California's demand for water dropped from 46 billion gallons a day in 2005 to 38 billion gallons a day in 2010, the latest figures available from the US Geological Survey.

In L.A., each day residents use about one-third of the water they used 25 years ago, according to Jeffrey Kightlinger, general manager of the Metropolitan Water District of Southern California (MWD). San Diego's residents are using 39 percent less water per person per day. Similar numbers appear for San Francisco and other urban areas.

These gains occurred even in the face of a burgeoning population.

Now, the current drought, which is heading into its fifth year, is sharpening the region’s focus on the need for finding a broader mix of approaches. This will involve experimentation, specialists say. The mix of measures will depend on local conditions and goals – the presence or absence of groundwater basins, for instance, or the need to meet environmental goals in addition to water needs.

“There is no silver bullet,” says Heather Cooley, who heads the water program at the Pacific Institute, a water-policy think tank in Oakland, Calif. “There will be will be successes and probably some failures along the way.”

Los Angeles and San Diego offer two potential visions of paths toward a more sustainable water future.

San Diego: harvesting the ocean

For San Diego, the drought of 1987-92 threw the region's need to diversify supplies into stark relief. In 1991, the San Diego County Water Authority relied on the L.A.-based MWD for 95 percent of its water. With the drought, the MWD cut its deliveries to the authority by nearly a third – a cut that lasted 13 months.

Since then, San Diego has coped through a mixture of conservation and a contentious water-transfer agreement with the Imperial Valley Irrigation District.

But the water authority has gone further, tapping the Pacific Ocean. In December, Poseidon Water, a desalination-development company based in Boston, opened a $1 billion seawater desalination plant in Carlsbad, Calif., 34 miles north of San Diego. It’s the largest desalination plant in the Western Hemisphere. The San Diego County Water Authority has committed to buying the plant's output of 50 million gallons a day.

“We’re just not blessed with a huge groundwater basin” like some other parts of the state are, says Bob Yamada, water-resources manager for the water authority.

On one hand, it seems like overkill. Despite the drought, the plant’s start-up came when the authority’s water supplies stood at 99 percent of normal. But it's a part of planning for the future. The authority expects the Carlsbad plant to supply 7 percent of its water needs by 2035 – a source that is stable in wet and dry years, Mr. Yamada explains.

Moreover, he adds, it’s relatively secure should a major earthquake damage aqueducts.

By 2035, San Diego’s water diversification program, including desalination, is expected to see the county’s reliance on MWD fall to 18 percent from its current 57 percent, though water from the Imperial Valley is projected to remain the largest source.

As of 2012, various water authorities in the state were considering as many as 15 other seawater desalination plants, according to a Pacific Institute tally.

If each was built and operated at maximum planned capacity, collectively they would supply 391 million gallons a day – roughly 1 percent of the state's total water demand in 2010.

But the vast majority of the state's water resources go to agriculture, largely in the state's Central Valley. The seawater desalination plants could supply up to 62 percent of the state's non-farm demand.

Although desalination technology has improved, the approach has strong downsides. It’s energy-intensive, carries potential risks for marine life usually at or near the base of the food chain, and generates a concentrated brine that must itself be diluted before it is returned to the ocean.

These are not insurmountable issues. Yet even in Israel, which now relies heavily on desalinated seawater, the move to desalination has been seen as a last resort after conservation, wastewater recycling, the replacing of leaky water mains, and rainwater capture had been exploited to the fullest, specialists say.

Seawater desalination “will be a part of California's water-supply portfolio,” notes Susan Jordan, executive director of the California Coastal Protection Network, an environmental organization based in Santa Barbara. “But given all the impacts associated with it, we want it to be used in the most sustainable manner.”

Los Angeles: harnessing the storm

In contrast to San Diego, Los Angeles sprawls across part or all of seven groundwater basins, which means it foresees no near-term need for desalination. But it does envision a change.

Between 2006 and 2010, on average Los Angeles drew 88 percent of its water from the MWD and the Los Angeles Aqueduct, which runs from the Owens Valley. The remainder came mostly from local groundwater, with a small contribution from recycled water.

Under the city’s latest plan, dependence on the MWD and the aqueduct should drop to 54 percent by 2035. The balance is projected to come from local groundwater, additional conservation, the use of recycled water, and the transfer of water rights from other jurisdictions.

But the latest weapon in Los Angeles’s drought arsenal is storm-water capture, which is finally getting the attention it deserves, says Andy Lipkis, founder and president of Tree People, an organization focused on the sustainable use of what he terms the region's urban watershed.

One inch of rain falling on the city represents 7.6 billion gallons of water, but some 3.8 billion gallons runs off into the ocean, Mr. Lipkis says.

Last August, the Los Angeles Department of Water and Power’s long-anticipated master plan for storm water reflected the emerging recognition of storm water's potential. It envisions projects in a range of sizes – from centralized settling basins covering acres to neighborhood yards – for capturing storm water and allowing it to seep into the ground.

Currently, the city receives an average of 831,000 acre-feet of storm water a year, but only 6 percent of it finds its way to groundwater reserves.

By 2099, the master plan envisions capturing from 179,000 to 258,000 acre-feet to recharge groundwater or for non-potable uses such as flushing toilets or watering yards planted with climate-appropriate trees and shrubs.

Such approaches highlight growing efforts to take a fresh look at local sources of water. While the state is making inroads to secure its urban water supply, its most water-intensive sector, agriculture, uses between 62 and 77 percent of the water supply, depending on the estimate.

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It, too, will have to change.

Says Ms. Cooley of the Pacific Institute: “This is a new era.”