Each weekday Walter T. Hammond and members of his crew count, one by one, every bird they see on six large ponds at the Kesterson Wildlife Refuge. The fewer birds they see, the better, says Mr. Hammond, an employee of the US Fish and Wildlife Service.
These are not ordinary, or even natural, ponds. They were dug as catch basins for irrigation water from farms miles away in the Central Valley -- and they are contaminated.
Kesterson is a permanent home for many wildlife species as well as a major stop for millions of waterfowl that migrate along what is known as the Pacific Flyway.
Water that makes cotton bloom on the west side of the fertile San Joaquin Valley ultimately drains into Kesterson. It now is known to carry elements that are killing or deforming birds, fish, and other wildlife in the refuge.
To put an end to this, the United States Department of the Interior has ordered that Kesterson be closed June 30 to any more flows of agricultural drainage. To comply with the order, the local water district this month started plugging the elaborate drainage system on 42,000 acres of farmland -- a move that many farmers once considered unthinkable.
John Pucheu Jr., a third-generation farmer, says he spent about $80,000, most of it borrowed, to install underground pipes on 320 acres to drain away irrigation water after it has seeped several feet into the ground.
``I considered it to be a long-term improvement to maintain productivity of the land,'' says Mr. Pucheu, who grows cotton, barley, sugar beets, and seed alfalfa.
``Never in my wildest dreams did I think that five or six years later we would have to abandon the entire project.''
The ``project'' began when Interior's Bureau of Reclamation built the Central Valley Project to deliver irrigation water to farmers in the San Joaquin Valley, which includes five of the nation's top 10 agricultural counties.
Because the salt content in the soil on the west side of the valley is so high, the Reclamation Bureau proposed disposing of the salty drain water through a canal that would empty into San Francisco Bay. But the canal, known as the San Luis drain, was completed only as far as the Kesterson marshlands when the money ran out. As a result, it was decided to drain the water into giant evaporation ponds on marshland adjacent to the Kesterson refuge.
But the evaporation ponds and the wildlife refuge have proved to be incompatible. Besides being salt-laden, the drain water contains traces of dissolved metals and the chemical element selenium.
Selenium, found naturally in the soil of many parts of the US, can reach toxic levels in arid areas with poorly drained soil -- such as the west side of the San Joaquin Valley.
The toxicity increases exponentially in each step of the food chain.
Farmers say the long-term solution to the problem is to remove the contaminants from the drainage water. But an affordable technology for such a process is still a few years off, and the Interior Department has not so far provided the $3.7 million needed to fund research for a selenium-removal plant.
The problem is not limited to Kesterson. In recent months, evidence has been found indicating that selenium poisoning may pose a threat to other wildlife refuges in the West.
High levels of selenium -- in some cases brought by drainage from farms irrigated by federal water projects -- have been found in Bowdoin National Wildlife Refuge in Montana, near Bosque del Apache National Wildlife Refuge in New Mexico, and on at least five other sites, according to a recent Interior Department study.
Pucheu says he and other farmers feel a sense of urgency because they are concerned that plugging the drainage system will cause selenium-laden water to rise into the root zone of their crops.
Last March, the Interior Department announced it would cut off irrigation water to the 53 farmers who send drainage water to Kesterson -- a move akin to taking their land out of production. But the department later granted a reprieve, with the expectation that flows to Kesterson would cease by June 30.
Since then, farmers have reduced their drainage flows by half through conservation. But they say they need an extension to 1988 to find a more permanent solution to the problem. Interior officials, however, are holding firm.
Environmentalists laud Interior's decision, saying farmers have been allowed to pollute the Central Valley long enough.
Marshes of the western San Joaquin are used by more than half of all migrating birds in the Pacific Flyway. Agricultural interests, environmental spokesmen add, have already plowed up much of the state's grasslands, shrinking the available habitat for such wildlife.
For now, US fish and wildlife officials at Kesterson are ``harassing'' ducks to keep them from swimming on or nesting near the evaporation ponds, Hammond says. Propane exploder guns fire intermittent blasts, and Hammond scares away stubborn coots by honking the horn on his truck as he drives down a narrow levee between the ponds.
In Washington, where Congress is grappling with huge spending cuts, expensive Western water projects are obvious targets.
Some lawmakers have questioned why the federal government is supplying farmers with ``subsized'' water to grow subsided crops that require subsidized drainage systems.
But the land in the San Joaquin Valley ``is so favorable in terms of climate and soil that, even with the drainage problem, it makes sense to grow crops here,'' says Stephen K. Hall of the Land Preservation Association, which represents local water districts on the west side of the valley.
The west side, which includes the 42,000 acres with the most immediate drainage problem, produces 40 percent of the nation's canning tomatoes and virtually all of its canteloupes, he says.
``It's hard to say it's one group's fault,'' Mr. Hall says of the Kesterson quagmire. ``But it's easy to see who is being victimized -- the ducks and the farmers.''