After Midland floods, a question: Where did waters carry toxic chemicals?

Terry Miller is worried but hopeful.

The longtime mid-Michigan environmental activist, who chairs the Bay County-based Lone Tree Council, has been waiting for flood waters to recede from Midland and surrounding areas following recent historic flooding, so he could get an up-close look at the damage. 

The sediment beneath the Tittabawassee River and soil in its floodplain are tainted with toxic chemicals — legacy pollution from Dow chemical company’s long history in the area — and Miller and other area activists have spent years watchdogging efforts to clean up the contamination.

He worries the floodwaters may have kicked up contaminated particles and deposited them in new places, or stripped recently-placed clean soil from lawns and parks, exposing the contamination underneath.

But during a recent drive past a cleanup site in Freeland, trees planted along the Tittabawassee to prevent erosion appeared to have done their job, holding clean soil in place. And Miller said flood control measures his group pushed to have adopted at Dow’s Midland headquarters seem to have been mostly successful at keeping water out of the compound while locking chemicals in. 

Still, he said, the water was too high to tell for sure and “I’m realistic enough to know that we need sampling to know whether recontamination has occurred.” 

As the floodwaters recede from mid-Michigan after the worst flood in the area’s history and probes begin into the dam failure that exacerbated Midland’s drowning, scientists and environmental activists are in the midst of a different investigation: What toxic chemicals did the floodwaters leave behind? 

A toxic legacy

The stakes are high. 

Dow Chemical has been a consistent presence over more than a century in Midland, where the company maintains its global headquarters and employs some 4,000 people. Since its founding in 1897, Dow has produced more than 1,000 chemicals used in everything from agricultural products to cosmetics. In the process, the company’s chemical manufacturing processes have emitted toxic chemicals in and around the city of 41,700 people, including dioxins and furans that still linger in the soil today from emissions decades ago.

The two substances may cause cancer, immune system problems and other health issues, according to the U.S. Agency for Toxic Substances and Disease Registry. 

The high concentrations of dioxins in river sediments, soils and even the tissue of animals living near the river prompted the federal Environmental Protection Agency to designate the lower 24 miles of the Tittabawassee River as a federal Superfund site. Contamination also extends downstream into the Saginaw River and Saginaw Bay, creating a total contamination footprint of some 50 miles.

Since cleanup work began in 2007, said Mary Logan, a project manager in the EPA’s Chicago office, the agency and Dow have cleaned up 18 contaminated sites in the Tittabawassee river and 33 areas along the riverbank. Efforts have ranged from dredging or capping contaminated river sediment to capping contaminated household lawns with a layer of clean soil. Work completed so far stretches nearly to the Tittabawasee’s confluence with the Saginaw River, and additional downstream projects are slated for years into the future.

Parties on all sides of the cleanup — Dow, regulators and environmentalists — say the effort has so far been a success. But they worry the high-velocity floodwaters that rushed through Midland and surrounding areas may have undermined years of work. 

Testing underway, results to come

Scientists with the Michigan Department of Environment, Great Lakes & Energy and, separately, Dow itself, have begun sampling sediment at key sites in the river’s floodplain, hoping to get a sense for what the floodwaters left behind.

Al Taylor, who manages EGLE’s hazardous waste section, said test results from initial samples taken last week at four so-called “trend locations” along the floodplain are expected back within a couple of weeks, and state scientists have plans to collect additional samples at four more sites this week.

Dioxin levels in those samples will be compared against past samples taken at the same sites to determine whether the floodwaters worsened contamination. While the locations were set up mainly to track dioxins and furans from Dow, Taylor said EGLE will also analyze the samples for other pollutants that could have been released in the floodwaters. 

“We had the river basically running through houses and garages and other things along the river system,” Taylor said. So in addition to dioxins and furans, “we also have a whole lot of other types of contamination that we need to worry about,” from heavy metals to pesticides and herbicides.

In the days immediately following the flood, I joined Miller and fellow Lone Tree Council member Michelle Hurd Riddick in a flyover of the Midland area that revealed widespread flooding at industrial compounds, junkyards and other locations with the potential to release pollutants. 

Taylor and a spokesman for Dow said scientists are waiting for floodwaters to recede further so they can get into still-wet areas to collect additional samples and survey already-completed cleanup sites for possible damage.

Sampling of floodplain soil began last week, Dow spokesman Kyle Bandlow said, and “will continue to be completed as areas continue to dry up and as it is safe to do so.” 

Bandlow said Dow plans to perform more “detailed inspections” of areas along the riverbank that have received cleanup treatments, but water levels are still too high to do so safely. All findings will be shared with EPA, he said.

EGLE scientists will also take tissue samples from the river’s fish, which would reveal any spikes in dioxin levels after the flood. 

In addition, said EPA’s Logan, additional targeted sampling and “more rigorous inspection” will likely be needed to determine whether the floodwaters carried contaminated soil to other areas along the Tittabawassee and Saginaw.

Initial results of visual inspections, though, she said, look promising. 

“It looks very similar to the flood of 2017,” she said. In that event — the third-worst flood in Midland’s history — contaminated riverbed sediments seemed to remain largely undisturbed, and soil caps placed on top of highly contaminated soils as part of the Superfund clean up effort held fast against the floodwaters.

While Miller, of Lone Tree Council, is pleased by the early impressions, he said it’s too early to draw hard conclusions.

“I would like to believe that the past 13 years have been a success,” Miller said. “But the sampling will be the proof in the pudding.”

‘The reality is, no one knows’

Fred Yanoski, director of the Midland County Health Department, said health officials are “considering all debris from the flood potentially contaminated.” 

Residents should take safety precautions when returning to flooded homes, wear gloves and boots to clean up debris, avoid contact with floodwaters and wash their hands if contact occurs, Yanoski said. 

For now, health officials are focused on near-term health threats, including potential spikes of bacterial diseases such as e-coli and tetanus, and viruses such as hepatitis A, that can spread on floodwaters or during cleanup. But chronic health concerns from chemical contamination in soils remain among “a bevy of concerns” on Yanoski’s mind.

Because the flooding originated upstream of Midland, where dioxin contamination is not a concern, scientists who spoke to Bridge for this article said they’re hopeful that clean sediment from upstream may have actually mixed with contaminated sediment downstream, diluting it and reducing overall dioxin levels in the Midland area.

Allen Burton, a professor of earth and environmental sciences at the University of Michigan who specializes in aquatic toxicology, said that’s a reasonable hope. But a worsening of existing contamination is also possible.

“The reality is, no one knows where the contaminated sediments are now,” he said. “It was such a huge flood, the currents were so large … it undoubtedly moved some of the contamination.”

While scientists await sampling results, work is underway to address potential contamination in public areas along the river, such as boat launches and parks where floodwaters deposited sediment. As part of Superfund cleanup responsibilities, Logan said, Dow is required to conduct annual clean-up in those areas after floods. 

Environmentalists and scientists are hopeful that the Superfund cleanup project’s design may have helped avoid worse effects from the flood.

Recognizing that the Tittabawassee is a “flashy” river that floods nearly every year, Logan said the EPA designed the cleanup plan to start upstream and work gradually downstream. That way, seasonal floods that uproot dirty sediments are less likely to recontaminate already-cleaned sites with dioxins from upstream. In addition, she said, upland cleanup sites in the river’s floodplain were designed to withstand flooding.

Another facet of the cleanup plan acknowledges that despite efforts to design cleanup with flooding in mind, recontamination remains a constant concern: Dow is permanently responsible for monitoring the condition of cleanup sites, and addressing any shortcomings.

“This was never going to be one of those sites,” Taylor said, “where Dow gets to walk away from it, because it’s all cleaned up.”