LEE VINING, Calif. - Not long ago, it was rare to see a yellow warbler around Rush Creek.
But on a recent bright and sunny morning, a yellow warbler plunged through a gap in a stream-side cottonwood forest, flying back to her nest and her chicks. Suddenly, she was stopped in midair - tangled in a mist net.
Field biologist Chris McCreedy found the bird in his snare a few minutes later. "Hi there, sweetie," he said as he untangled the bird, recorded its vitals - a 2-year-old female that weighed 10 grams, about as much as a ball point pen - and gently clamped an identification band to one of her legs.
Then he opened his palm and released her back to Rush Creek, a major tributary to Mono Lake in the eastern Sierra, the focus of an agonizingly complex and decades-long effort to heal a vast wilderness devastated by Los Angeles' insatiable thirst.
Now, 14 years after the city was ordered to reduce the quantity of tributary water it had been diverting into the Los Angeles aqueduct since 1941, Rush Creek has among the highest concentrations of yellow warblers in California - roughly three pairs per 2 1/2 acres.
"Restrict grazing and bring back the water and things really start hopping," McCreedy said.
That's the good news. Orchestrating the restoration continues to be a challenging process for the Mono Lake Committee, a nonprofit group of environmentalists and citizens organized in 1978 to save and protect a bowl-shaped high country ecosystem roughly half the size of Rhode Island.
Nonetheless, Geoffrey McQuilkin, executive director of the 16,000-member group, said he often is asked, "Why is the Mono Lake Committee still around? You got the water you needed years ago. Isn't Mono Lake saved?"
Over the years, the committee has stopped city water diversions, potentially damaging highway-widening projects and proposed lake-shore development. But its biologists still can't explain why Rush Creek's trout are not growing as large as expected.
Then there are the endangered willow flycatchers, whose population soared with the return of Rush Creek's riparian vegetation but who are being hit hard by an unforeseen threat: nest-invading brown cowbirds attracted by the rising brreet songs of the flycatchers' mating rituals.
Before the tributary streams were diverted, flycatchers commonly were found in what was once a lush expanse. Flycatchers began showing up again in about 2000 but in far fewer numbers. Now, they are in sharp decline statewide because of habitat loss and competition from cowbirds.
"I'm so worried about this population of about 10 flycatchers going extinct," McCreedy said, "that I've been going around town telling people to keep cowbirds away from backyard bird feeders."
Metaphorically speaking, the nearly million-year-old alkaline Mono Lake at the base of the jagged eastern escarpment of the Sierra Nevada couldn't be farther from the congested subdivisions surrounding Los Angeles, about 350 miles to the south. But that's where the water from four of Mono Lake's five tributary streams has been going since 1941.
By the late 1970s, the environmental degradation in the region just east of Yosemite National Park was on full view. Tributary streams dried up. The lake level had dropped more than 40 feet and the water had doubled in salinity, leaving behind smelly salt flats scoured by choking dust storms. The increasingly salty water threatened to kill brine shrimp, a favorite food of the 50,000 California gulls that breed here each year.
Further decline, the committee warned, would transform Mono Lake into an "ugly sump surrounded by a bathtub ring of sterile white alkali encrustments."
The sex life of gulls became a touchy political drama for Los Angeles when a declining water level revealed a land bridge connecting an island rookery to the shore, allowing coyotes to pad across and feast on the birds and their nests. The Army Corps of Engineers tried to blow up the land bridge with dynamite, but the muck only exploded, then fell back in place.
Formal protests began with a lawsuit filed in Mono County Superior Court in 1979 against the Los Angeles Department of Water and Power by the Mono Lake Committee, Audubon Society and three local residents. The lawsuit alleged violations of public trust and creation of a public and private nuisance by the exposing of 14,700 acres of former lake bed.
In 1983, the U.S. Supreme Court let stand a California Supreme Court ruling that environmentalists have the right to challenge the amount of water that Los Angeles imports from tributaries of Mono Lake. The California State Water Control Resources Board ordered minimum flows restored for all diverted streams, while allowing the agency to divert some water for consumption in Los Angeles.
This year, as the committee celebrates its 30th anniversary, Mono Lake, while still far from its natural conditions, is on the mend.
On a recent weekday, the northwest corner of Mono Lake reflected the alpine peaks beyond as migrating Wilson's phalaropes - making a pit stop to bulk up during their transcontinental journey to Argentina - probed its shallows to breakfast on a species of brine shrimp found no place else.
California gulls snapped at clouds of tiny black alkali flies. Ospreys surveyed the placid lake from large nests of sticks on moonlike tufa towers, formations built up from deposits of limestone from freshwater springs.
But the water in Mono Lake remains 34 feet below its pre-diversion level, and it still has 8 vertical feet to rise before it reaches the target of 6,391 feet above sea level. That was set by the Water Control Resources Board, and if the mark isn't hit by 2014, the panel will hold a hearing on the matter.
This year, the lake level is expected to rise a foot. But each advance seems to come with a setback: The water level is expected to fall a foot by year's end.
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