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This story comes from our partner, 90.5 WESA.

Many Pittsburghers know that the city’s three rivers are cleaner than they were at the height of its steelmaking heyday, yet still suffer from serious contamination. But what about the many streams in the area that feed into those rivers?

The Pittsburgh Water Collaboratory at the University of Pittsburgh published a study this month that looked at more than three dozen possible pollutants at 25 different tributaries and sewage outfalls. The study, which was self-published on a public website, found that the impacts of acid mine runoff and sewage overflows into the river continue to adversely impact the streams. And they found additional contamination from rare toxic metals, such as cadmium, which are associated with the production of coke, a key ingredient in steelmaking.

The authors of the study said most water quality data near Pittsburgh has been collected on the Ohio, Allegheny and Monongahela rivers directly, rather than from the streams that feed into them. The authors hope these new results will form a baseline to understand what kind of contaminants are in the Pittsburgh-area streams and what work is needed to clean them up.

Cleaner streams would improve the quality of life in the region, said Dan Bain, an associate professor at Pitt in the Department of Geology and Environmental Sciences, who also serves as the deputy director of the Water Collaboratory.

“The tributaries are an underutilized resource,” he said. “And if we can make them cleaner, we clean up the major rivers, but we also make it a place where everyone can interact with the region’s waters.”

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The study conducted most of its testing at locations where prominent local streams flow into the city’s three rivers. They tested as far southeast as Turtle Creek on the Monongahela, as far northeast as Deer Creek on the Allegheny, and as far west as Montour Run on the Ohio.

The study collected four samples at each of the 25 sites, one during each season. That’s because weather patterns can impact the kinds and amount of pollution found. The amount of some pollutants, like phosphate, varied widely by season, according to Heather Hulton Vantassel, the executive director of Three Rivers Waterkeeper, which collaborated with Pitt on the study. Vantassel said the group used its small boat and a couple kayaks to collect the samples.

A map showing the three rivers and tributaries with blue dots to signify the sampling locations


One of the most surprising findings was the existence of cadmium, Bain said.

We’ve got a lot of samples from across the nation in urban systems. And very rarely do you get hits of cadmium,” he said.

Most of the cadmium in the water was found near two historical coking sites: on Neville Island, which was home to the now-shuttered Shenango Coke Works, and near U.S. Steel’s Clairton Coke Works, which is the largest active coke production facility in the United States. Cadmium is toxic in high doses and can weaken bones, though the levels found in this study didn’t exceed the Environmental Protection Agency’s limit for drinking water. Bain said the cadmium can build up to higher concentrations in the flesh of fish eaten from these streams.

During May 2022 — one of the four testing periods — the study found cadmium in streams all over the city, not just near industrial coke facilities. Part of the reason for the variation may have been the unusually dry weather during that time, Bain said. Dry weather can impact how pollutants are absorbed in the water as well as increase their concentration.

How to clean up pollution

Bain said that it would help if the many local governments in Allegheny County coordinated more. For example, he said, streams in the South Hills still suffer acid mine runoff from the many historical mines in the area.

“But if Mt. Lebanon, Bethel Park, Whitehall, Baldwin, West Mifflin got together and dealt with those mine pools, we’re going to start pulling iron and manganese out of those systems. Once you remove that, that stream has a much better chance of sort of reestablishing some of the natural processes that make it look like the stream that we expect [it] to be.”

The quality of the water in the streams could take on increased importance in the coming years, Bain said. The Allegheny County Sanitary Authority has plans over the next 13 years to remove billions of gallons of sewage runoff from the area’s sanitary system by expanding its plant and building large underground storage tunnels. Once that sewage is removed, according to Bain, the threat to waterways posed by many of the legacy pollutants identified in this study will become increasingly apparent.

Vantassel said that Pennsylvania’s Department of Environmental Protection will need additional resources in order to clean up Allegheny County’s streams, more than half of which are designated as in need of remediation. Right now, she said, the DEP doesn’t have the resources to issue fines every time a company exceeds its water pollution limits.

“What often happens is there’s just a notice of violation and it doesn’t come with any actual penalty to the company,” Vantassel said. “But if there was a true penalty for exceeding these limits that these industries have, they would start operating within their limits.”

A spokesperson for the DEP said they would reach out to their experts for comment on the report but didn’t send a response prior to publication.

Some aspects of cleaning up the region’s streams could be more complicated. The study found high levels of phosphorus and nitrogen — common ingredients in agricultural fertilizers, pet waste and raw sewage that can make their way into waterways via runoff or overflows — which can lead to algae blooms. The Ohio River has been plagued by these blooms during the last decade, most of which have started near the Ohio border, Bain said. Those blooms can be dangerous and are expensive to filter out of local water supplies.

But some of the existing pollution in the streams is making the water more acidic, which prevents algal blooms from forming. But if the metals contributing to higher acidity were removed from local streams, Bain said, then attention might need to shift to also reducing the amount of nitrogen and phosphorus.

Vantassel said it’s important to put the current stream pollution in perspective. The area’s streams and rivers used to be much more polluted with industrial runoff 50 years ago, but new environmental laws and regulations have improved the region’s overall water quality.

“We’ve come a long way so we know we can improve our waterways,” she said. “We know when we find our sources and we hold polluters accountable, we can clean our waters.”