Thousands of birds flying across the Western plains each year fatally mistake oil pits for bodies of water. Once the birds land, their feathers become coated and they die. In its first attempt to address the problem, the Environmental Protection Agency recently fined Texaco Refining and Marketing Inc. and four other companies $300,000 and ordered them to clean up the 32-acre Powder River Crude Processors facility near Casper, Wyo. The cleanup, which calls for draining the pits, could cost as much as $8.9 million. In the past, the Environmental Protection Agency could not sue an oil facility unless it posed a hazardous waste danger or produced waste that posed "an imminent and substantial endangerment to human health or the environment," says Terry Anderson, chief of the agency's Region 8 hazardous waste division in Denver. Because federal laws classify oil waste as non-hazardous, officials had to prove the pits actually kill wildlife, which they did through a 1991 on-site inspection. "I don't think people understand the magnitude of this problem," says U.S. Fish and Wildlife biologist Brent Esmoil of the Mountain-Prairie Region's Ecological Services office in Grand Island, Neb. Esmoil spent two years studying wildlife mortality at oil pits. He says the 100-foot-long pits at Powder River have probably been killing waterfowl since they opened in 1979. It was hard to detect because bird carcasses sink to the bottom.