Looking out from the banks of the river that once ran through this rugged valley beside the Sierra Nevada range, Mike Prather sees only an ugly heap of stumps, weeds and dried mud. The water is long gone.

It has been that way for nearly a century, ever since Los Angeles began quenching its insatiable thirst by buying up nearly all the land and building what some folks here still bitterly call "the big straw," the 233-mile aqueduct that swiped the local water supply and gave the metropolis its life.

The Owens River was the first casualty of that monumental engineering feat, sucked dry and all but left for dead. Until now.

Prather, a retired science teacher and environmental activist in the Owens Valley, no longer comes to the river to lament its loss. He comes to savor a remarkable new plot twist in the ceaseless water wars of the West: Los Angeles soon may have no choice but to restore the river's old flow.

"There's a lot of people here who feel that this battle was lost long ago," Prather said as he pointed to the parched riverbed. "They completely accept the omnipotence of L.A. and think it's always going to get whatever water it wants, no matter what you do. But I think we're about to show them that's not true."

To revive the river, which curves for more than 60 miles through the Owens Valley, Los Angeles would have to modify the aqueduct and give up millions of gallons of its precious water -- an amount equivalent to what it sends about 40,000 families in the city every year.

That momentous step would create an environmental restoration project like none other in the West, launched at a time when the arid region is urbanizing at dizzying speed and getting ever more desperate to find new sources of water.

For residents in the valley, it would also be a historic milestone, a sign that Los Angeles is at last atoning for what they regard as its original sin.

"This has been a long time coming," said Greg James, the director of the water department in Inyo County, which includes the Owens Valley. "There aren't many places in the West where 65 miles of a river have been dried out, and now 100 years later there's an opportunity to get it back. I'm optimistic it's going to happen. But some people here are still skeptical of anything L.A. says."

"Either you bring the water to L.A. or you bring L.A. to the water."

-- John Huston as Noah Cross, in the film "Chinatown."

The year was 1904. Los Angeles was booming. Its population had doubled since the turn of the century to about 200,000 residents, and its leaders saw only gold in more growth. But the city needed more water, badly.

Fred Eaton, a former mayor, had an audacious idea: Why not get it from the Eastern Sierra, about 250 miles to the north, using an aqueduct that relied on gravity to send water from the high country down to the Los Angeles basin?

It was just crazy enough to work. Eaton and his associates slyly began buying farms and ranchland in the Owens Valley, which stretches for 100 miles. The deals included water rights. No one said anything about an aqueduct.

Eventually, they legally purchased several hundred thousand acres -- one of the biggest and most cunning water grabs in the history of the West.

"They wound up buying whole towns, literally," James said.

Locals hardly knew what had hit them. Construction of the mammoth aqueduct, orchestrated by the famed engineer William Mulholland, soon began. It took six years to build, opened in 1913, and soon provided Los Angeles with 75 percent of its water supply. The valley would never be the same.

First the Owens River dried up. Then the 60-square-mile Owens Lake into which it flowed became a giant dust bowl that would cause respiratory problems for generations of valley residents. The fragile local economy collapsed.

Even now, Los Angeles officials bristle at charges that the whole plan was a dirty trick -- and suggest that mostly public ownership has brought the valley lasting benefits, too. It is a place out of time today, a collection of quaint towns along Highway 395 that is one of the few places in California not beset with traffic, smog or runaway suburban development.

"Yes, there was a certain amount of subterfuge back then," said Jerry Gewe, chief operating officer for water at the L.A. Department of Water and Power. "But the fact is, it was all willing buyers and willing sellers."

The aqueduct spurred growth in Los Angeles that has never relented. By the 1960s, the city had another water supply-and-demand problem to solve. It looked again to the Owens Valley and built a second aqueduct 177 miles long, to be filled by the intensive pumping of underground water.

Local officials and civic groups say that tactic devastated wildlife and vegetation. Using new environmental laws, they sued Los Angeles for damages in 1972 -- then spent 25 years squabbling.

In 1997, the city agreed in a court settlement to restore the Owens River, but that pact appeared to be stalled until the state stepped in late last year and filed a lawsuit demanding that Los Angeles get moving on the project. Soon afterward, the city agreed to new deadlines for returning water to the river.

"While the city relies heavily upon the Owens River for our high-quality drinking water," Los Angeles Mayor James K. Hahn said at a ceremony earlier this year to announce the restoration plan, "preserving the Eastern Sierra and the Owens Valley is just as important."

The reckoning is at hand. Maybe.

"On a map, the Owens Valley was still there, but it had ceased to exist as a place with its own aspirations, its own destiny."

-- Marc Reisner, "Cadillac Desert."

Water could be returned to the Owens River next year, but a few technicalities still have to be resolved, and lingering tensions over them could become deal breakers.

Los Angeles has until the end of June to submit a final environmental report on the river renewal to a court. It is not clear whether the city will meet that deadline, but Gewe expects the project to proceed. "We've stepped up to the plate," he said. "The question mark is the timetable."

To residents in the Owens Valley, that sounds like a ploy. "We've been hearing it for years," said Mark Bagley, who leads the local chapter of the Sierra Club. "The city seems to be continuing not to make the best effort to move forward. They're looking for every advantage they can find to save water."

Los Angeles almost certainly will have to rely more on conservation, which is no longer an optional habit in the West.

The city already is going to extremes to save water. It has enticed more than 1 million residents to install toilets designed to use less water. It is also giving away low-flow showerheads and offering cash rebates to families that buy water-saving washing machines.

The campaign is working: The city uses roughly the same amount of water now as it did 20 years ago, even though its population has grown by about 700,000 residents. But now it will have to do even more conserving. Los Angeles currently relies on the Owens Valley for about one-third of its water.

"Without question, filling the river is going to cost L.A. a significant supply," James said.

The plan calls for pumping enough water into the river to create a waist-deep flow. That's far below its historical levels, but should be enough to cultivate new trees along its banks and create a vibrant new habitat for fish and game.

A restored river also could bring recreational crowds to the Owens Valley for fishing, kayaking and bird-watching. "It will really help the local economy," Prather said, "if more people come up here to bait a few hooks."

Shifting water from the aqueduct will be the simplest part of the project, requiring only a few engineering maneuvers. But on the southern end of the river, a pumping station will have to be built to manage the flow. Officials are planning to allow some water to seep into the dry Owens Lake, where Los Angeles has begun trying to stop the dust problem, and to send some back to the aqueduct after it has made its way through the river.

Brian Tillemans, the L.A. water department's watershed resource manager in the Eastern Sierra, said the river's recovery could take seven years.

"It's going to be fantastic habitat," he said. "This project is almost unprecedented in the West. I think the skepticism is going to disappear once it gets started. People will be too busy enjoying the river."

Prather sounds weary of the long fight. But as he walked along the river's bleak banks, he said he has never felt so close to victory -- to seeing bass jump from the water and pretty cottonwoods and willows rise up from the dry dirt.

"It's not much to look at now," he said. "But it's coming back."

Activist Mike Prather stands on gates built in 1913 to divert the flow of the Owens River to Los Angeles.