The Yellowstone River was one of more than 200 sampled as part of the country's largest water quality assessment project.
Neal Herbert / Yellowstone National Park

More pesticides are permeating urban streams

But rural rivers are getting cleaner, a new study says.

 

If you live in a city, the U.S. Geological Survey has some bad news for you: There’s a good chance your water is contaminated. A USGS study released earlier this month monitored more than 200 streams from 1992 to 2011 and found that the number of urban waterways contaminated with pesticides increased from 53 percent in the 1990s to 90 percent the following decade. Most pollutants were found at levels only harmful to aquatic life like fish, frogs and insects, while the number of streams with contaminant levels that pose a risk to human health actually dropped. Yet new chemicals are still permeating the environment and our understanding of their negative effects is limited. 

Still, the USGS study is the country’s most comprehensive assessment of water quality to date, and it does offer some good news — or at least, what passes for good news on the environmental beat. For one thing, farmers are doing a better job at reducing runoff:  The number of agricultural rivers with pollutants exceeding aquatic life benchmarks decreased from 69 percent to 61 percent, while pollution in mixed-use streams stayed about the same.

The study also demonstrates how effective federal regulators can be at reducing pollutants — and how slow they are to catch up with real-world conditions. Diazinon, for example, a commonly used pesticide in the ‘90s that’s toxic to bees and birds, was phased out of residential use by the Environmental Protection Agency in 2004. Levels in waterways have since dropped dramatically. Yet for each toxin removed, dozens more are added: Even as the EPA was phasing out diazinon, a new pesticide called fipronil — classified as a “possible human carcinogen” — began showing up in high concentrations in urban streams, apparently in runoff from gardeners.

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USGS National Water Quality Assessment Program

Altogether, some 15,000 new chemical compounds identified in patents and academic literature are added to the federal database of the American Chemical Society every day, and the “EPA simply cannot keep pace,” writes Jerald L. Schnoor, editor-in-chief of the society’s Environmental Science and Technology journal. “Their budget is in decline and the list grows exponentially.”

The EPA isn’t the only federal agency that can’t keep pace. Due to “resource constraints,” the USGS study was only able to monitor about half of the 400 herbicides and pesticides widely used in U.S. agriculture, meaning that serious pesticides like neonicotinoids — linked to widespread bee decline and banned in Europe — weren’t included in water quality assessments. Nor were unregulated chemicals used by oil and gas companies.

Plus, even as the public health organization NSF International recently found that 87 percent of Americans are concerned about trace pesticides in their water and the USGS report credited the reduction of pesticide pollution to EPA regulations, the U.S. House of Representatives is quietly working to reduce the EPA’s ability to regulate stream pollution. On July 31, the House passed Ohio Republican Bob Gibbs’ “Reducing Regulatory Burdens Act,” which would allow regulated pesticides to be dumped into navigable waterways without a permit. On Sept. 11, it followed suit with Florida Republican Steve Southerland’s “Waters of the United States Regulatory Overreach Protection Act,” which would exempt seasonal streams and some tributaries from Clean Water Act protections. Both bills stalled in the Senate. 

USGS Pesticide National Synthesis Project
EPA regulations led to a vast decrease in the use of diazinon, toxic to birds and bees, over two decades.

Krista Langlois is an editorial fellow at High Country News. She tweets @KristaLanglois2.