Keith Matheny

Detroit Free Press

The rivers that serve as the lifeblood of the Great Lakes abound with organic waste compounds, including pollutants from car exhaust, factory smokestacks and tar, insecticides and herbicides and detergent ingredients.

And three Michigan rivers are among the worst of the worst for the compounds: the Clinton and Rouge rivers in Southeast Michigan and the St. Joseph in Southwest Michigan, according to a recently published study by the U.S. Geological Survey — the most comprehensive look yet at organic waste compounds in Great Lakes tributaries.

The Clinton, Rouge and St. Joseph rivers top the list with the highest number of organic waste compounds found in water sampling USGS conducted throughout the Great Lakes basin in five states over four years, from 2010 to 2013. The amount of the pollutants also was disturbing — both the Clinton and Rouge rivers had five organic waste compounds related to incomplete fossil fuel burning, such as car exhaust and coal-fired power plants, that were 10 times higher than water-quality benchmarks.

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"The Rouge and the Clinton were among the worst sites overall, almost across the board, for what we were looking at," said Austin Baldwin, a USGS hydrologist who led the tributaries study.

The compounds are known to disrupt the endocrine systems — which produce hormones — of fish and other organisms, Baldwin said. They can act like the hormone estrogen and lead to reproductive disruption, including causing male fish to turn into females, he said. And concentrations of the compounds at levels high enough to cause such changes were found not only in the Clinton, Rouge and St. Joseph rivers in Michigan, but also the Au Sable, Saginaw, Raisin and Ontonagon, he said.

"Some of the samples we collected in the rivers had concentrations of these estrogenic chemicals comparable to concentrations in effluent" from wastewater treatment plants, Baldwin said.

Even low levels of the compounds, affecting the smallest shrimp-like invertebrate creatures in the water, cause a ripple effect up the aquatic food chain and could ultimately impact Michigan's prized, multibillion-dollar fishing tourism industry.

The science on this low-level toxicity is still somewhat new, Baldwin said.

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"There used to be this idea that higher concentrations led to higher effects, but in some cases, that doesn't seem to be true," he said. "For some compounds, low concentrations may have more effects than high concentrations. It's really complicated."

The USGS study sampled streams both at times of high runoff and low-flow conditions. While some seasonal differences were noticed — pesticides and herbicides were found in higher concentrations in the summer than in the spring, fall or winter — stream flow condition had little effect on compound occurrences or concentrations, the study found.

Overall, across the Great Lakes basin, one or more water quality benchmarks were exceeded in 35% of all 709 water samples taken from 57 tributaries, representing about 41% of the total water inflow into the Great Lakes. The samples came from rural, agricultural areas to urban centers that, in addition to southeast Michigan, also included the Milwaukee, Toledo, Cleveland, and Gary, Ind., areas.

The most prevalent compounds found in the Clinton, Rouge and St. Joseph rivers at relatively high concentrations were so-called polycyclic aromatic hydrocarbons, or PAHs. According to the federal Agency for Toxic Substances and Diseases Registry, they're a group of chemicals formed during incomplete burning of coal, oil, gas, wood, garbage or other organic substances. They're often found in mixtures with gasoline and diesel exhaust or emanating in soot from industrial smokestacks.

"Especially with PAHs, there are a lot of different sources in an urban area," Baldwin said. "Any combustion of fossil fuels produces PAHs. Those PAHs settle on streets and sidewalks and, when it rains, they run off into the streams."

Other studies have noted coal tar pavement sealants as a key source of PAHs, he said — "those sealers people put on their driveways and parking lots to make them nice and black."

"Cars drive on them; they're getting rained on; snow plows scrape them. Those coatings get broken down over time and washed into the streams."

Farm fields and lawns are the main sources for pesticide and herbicide pollutants. And many of the organic waste compounds move right through wastewater treatment plants and out the other side. But Baldwin said it's inappropriate to fault plant operators.

"Some of this stuff doesn't even see the wastewater treatment plant; a lot of it just gets washed directly off the streets, farmers' fields or lawns," he said. "Some of it does go into the wastewater treatment plant, but they are not designed to remove this kind of stuff. That's not their task."

Karen Hanna, operations manager at the nonprofit Friends of the Rouge, said the findings are not a big surprise.

"The Rouge River has been designated as one of the most polluted rivers in the Great Lakes region," she said. "The Rouge River is one of the most highly urbanized rivers in the country.

"There are a lot of issues facing this river. There are issues with industry; there are issues with people. There's overdevelopment and taking away the natural surface of the Earth. When you replace ground with impervious surfaces like driveways and rooftops, there's no place for storm water to go. It goes into the wastewater treatment plant, or it goes into the river."

Matt Einheuser, watershed ecologist at the nonprofit Clinton River Watershed Council, said the findings of the USGS study can help explain to residents and communities the importance of green infrastructure and other management practices to mitigate the impacts.

"We work with our communities to provide education and presentations on storm-water issues that deal with these compounds and how residents can help lower these numbers," he said, referencing the council's RiverSafe LakeSafe program.

Michigan Department of Environmental Quality officials said they were unaware of the USGS study.

"We're going to look into it at a little more detail, talk to our USGS colleagues here in Lansing," said Mike Alexander, the DEQ's environmental manager in the surface water assessment section of the agency's Water Resources Division.

The rivers are already heavily monitored for chemicals such as PCBs and mercury that often show up in fish, leading to advisories on how, how much and whether to eat certain fish caught at certain locations, Alexander noted. E. coli bacteria is another frequent problem for which rivers are already constantly monitored, he said.

But the organic waste compounds outlined in the USGS study "are more emerging contaminant concerns," he said.

Baldwin said he hopes the study helps highlight the importance of improving storm-water management, and serves as a baseline for future studies of river quality around the Great Lakes.

"Just because we're not seeing screaming-high concentrations in a lot of places doesn't mean there is not a concern," he said. "We were collecting a handful of samples over three or four years. What are the chances we were collecting at the time these compounds were at their highest?"

Contact Keith Matheny: 313-222-5021 or kmatheny@freepress.com. Follow on Twitter @keithmatheny.

Waste compounds found at the highest levels in Rouge, Clinton, St. Joseph rivers

Benzo(a)pyrene

Pyrene

Fluoranthene

The three compounds are polycyclic aromatic hydrocarbons, or PAHs. Found in gasoline and diesel exhaust, soot smoke from industry and asphalt and coal tar, PAHs are known carcinogens. Multiple samples from the Rouge and Clinton rivers showed PAHs at levels 10 times greater than water quality benchmarks.