BOSTON -- Stretches of the Blackstone River in central Massachusetts weave through areas of wilderness where the absence of houses and other man-made structures makes it seem like an undisturbed river far from civilization.
But the serene and idyllic setting masks the pollution below the surface and lodged in the sediment along its banks.
The 46-mile-long Blackstone, whose headwaters begin in Worcester, Mass., receives effluent from the city's waste-water treatment plants. Oil from cars and other sources of urban runoff seep into the water. The river, which used to be lined with textile mills during the Industrial Revolution, is still contaminated from the dyes used at that time.
"Worcester's the bathtub, and the river's the drain, so as Worcester washes itself in the bathtub, everything goes into the river," says Russell Cohen, rivers advocate for the Massachusetts Department of Fisheries and Wildlife.
While restoration efforts have improved the Blackstone significantly, it "never really has a chance to be clean because right in the very beginning of the river is where Worcester is, and the pollution is carried downstream."
Twenty-four years ago, the Cuyahoga River in Cleveland became the symbol of severely polluted rivers when it caught fire. Over the years, industries and municipalities had openly dumped chemicals, raw sewage and other wastes into the country's waters.
When the Clean Water Act was passed in 1972, the immediate mandate was to remove this visible goo from the water by stopping point-source pollution -- pollution that can be traced to a specific source, such as a pipe spewing factory waste. Today much of the point-source pollution has been addressed, and many rivers no longer are topped with chemical foam or run red with dyes, though past contamination from dyes still affects even relatively clean waterways.
But river advocates say rivers across the United States, like the Blackstone in Massachusetts, are now threatened with pollution that has become more subtle and insidious. "The rivers are apparently cleaner, but it's our viewpoint that river ecosystems are declining pretty badly," says Kevin Coyle, president of American Rivers, a river-conservation organization in Washington, D.C.
Mr. Coyle says that much of this degradation is caused by nonpoint-source pollution, which has become the leading source pollution into the nation's water bodies.
Nonpoint-source pollution is loosely defined as runoff from farms, city streets and industry. When it rains, fertilizers, chemicals, pesticides, oil from cars, and other wastes are washed into rivers and streams.
The effects are slow but cumulative, Mr. Cohen says. The runoff feeds rivers with too many nutrients, which lead to algal blooms. The blooms use up most of the oxygen, so other organisms can no longer live.
Mr. Coyle says rivers then become devoid of life, even though they may look clean. "The river ecosystems, . . . the sensitive little critters that live in the streambeds are endangered, and until we can figure out how to deal with nonpoint pollution, we're not really going to save the rivers," he says.
Just how many rivers in the United States are in trouble?
According to Geoffrey Grubbs, director of the Assessment and Watershed Protection Division at the Environmental Protection Agency (EPA), the United States has roughly 2 million miles of rivers and streams. Because such a large number is hard to monitor, only one-third is measured for water quality. Of that fraction, about 240,000 river miles are not meeting water-quality standards, which the EPA defines as fishable or swimmable.
The good news, Mr. Grubbs says, is that most of the nation's water is meeting EPA objectives.
Water bill is source of hope
River advocates are looking to the Clean Water Act, which is up for reauthorization this year, to address some of the nonpoint-source pollution problems. Both the House of Representatives and the Senate plan to introduce a bill this fall.
"The debates will be very thorny, because to address nonpoint-source pollution you have to deal with land-use issues," Mr. Coyle says. "That's a little different from telling a factory it can't dump stuff in the rivers."
Mr. Coyle says one way to slow agricultural runoff is to have narrow strips of land along rivers that act as natural filters. A handful of states have already enacted laws requiring new development to be set back from rivers a certain number of feet.
In April, American Rivers, a river-conservation organization in the District of Columbia, announced its 1993 list of the 25 most endangered and threatened rivers.
According to American Rivers, these face serious environmental threats from industrial pollutants, storm water runoff, sewage and power dams, which upset ecosystems.
The most endangered rivers
1. Rio Grande/Rio Conchos River system (Colorado, New Mexico, Texas and Mexico)
2. Columbia/Snake River system, including the Yakima tributary (Washington, Oregon, Idaho and Canada)
3. Everglades (Florida)
4. Anacostia River (Maryland and Washington)
5. Virgin River (Utah, Arizona and Nevada)
6. Rogue/Illinois River system (Oregon)
7. Penobscot River (Maine)
8. Clavey River (California)
9. Alsek and Tatshenshini River system (Alaska and Canada)
10. Platte River (Nebraska)
Fifteen highly threatened rivers
11. Animas River (Colorado)
12. Beaverkill (lower) and Willowemoc river system (New York)
13. Blackfoot River (Montana)
14. Eleven Point River (Missouri)
15. Great Whale River (Quebec, Canada)
16. Little Big Horn River (Wyoming)
17. Los Angeles River (California)
18. Moose Creek (Alaska)
19. Skokomish River (Washington)
20. St. Mary's River (Virginia)
21. Susquehanna River (Pennsylvania)
22. Tennessee River (Kentucky)
23. Thorne River (Alaska)
24. White River (Arkansas)
25. Yuba River, South (California)