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GRASPING FOR SOLUTIONS - While many states are failing to protect rivers and watersheds from polluted runoff, some communities are taking matters into their own hands - diffuse pollution threatens American waterways
National Wildlife, April-May, 2001 by Joby Warrick
More than two-thirds of the nation's state governments still lack a workable TMDL program, NWF found. "Not one of the 50 states has done what the law requires," it said. The result: Despite a public perception of steadily cleaner rivers and lakes, progress has stalled in many areas and has actually reversed in others. Some examples:
* Fertilizers and animal waste from factory livestock farms have helped trigger an unprecedented number of algal blooms, destructive growth spurts that clog waterways and suffocate fish. Most notorious were outbreaks of toxic algae, including the organism Pfiesteria piscicida, blamed for killing a billion fish in coastal North Carolina.
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* Increased monitoring and continued mercury contamination in lakes and rivers has led to a doubling of fish-consumption advisories (warnings against consuming certain fish) from 1993 to 1998. Much of the mercury originates as smokestack emissions and falls to Earth with rain and snow.
* Farm chemicals from states in the Midwest have flowed down the Mississippi River, helping feed a growing "dead zone" of barren, oxygen-depleted water in the Gulf of Mexico. The size of the dead zone ballooned in the early 1990s and grew to 7,500 square miles before shrinking last summer due to drought in the plains states.
Even where the problems are not so dramatic, chemicals in polluted runoff have created the equivalent of a low-grade toxic-waste spill that now extends to virtually every river and stream in the country. In a landmark survey completed in 1999, the U.S. Geological Survey (USGS) found at least one pesticide in almost every water and fish sample it collected. In fact, more than half the streams tested in the agency's National Water Quality Assessment Program contained at least five pesticides. The levels of these individual contaminants were usually within EPA safety limits, but the combinations and ubiquity of the chemicals raised a troubling question: Do chronic, low doses of multiple pesticides add up to a greater risk for wildlife and people? "We simply don't know the effects of sustained exposure to mixtures of chemicals on an aquatic ecosystem," says USGS scientist Bob Gilliom.
The seesaw fortunes of the Clinch River's mussels are a case study in how changes on land can impact river species and throw entire ecosystems out of balance. Geology and geography conspired to make the waterway one of the world's great habitats for mussels. Over time, the creatures became the biological cornerstone for a large and diverse wildlife community in and around the Clinch that includes more than 400 rare plants, animals and insects.
However, for an animal that lives in a rock-hard vault and can survive up to 60 years, the mussel is extraordinarily delicate. "Mussels were once 20 percent of the river's entire biomass," notes Beaty, who conducts research for The Nature Conservancy.
By the late 1980s, the number of mussel species in the Clinch had dropped from 60 to 40, with 26 of the remaining species now facing a serious threat of extinction, scientists say. "The mussels are the piece of the puzzle that disappears first when things start to go wrong," Beaty says. "The good news is, if it's early enough, even if you lose some of the species, there's still a chance you can save the ecosystem."
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