Don’t Forget to Read the Fish Advisory
The Black Butte Mine Superfund site outside of Cottage Grove has been contaminating the waterway with mercury for decades. How do we keep the public informed on the risks?
The Willamette Valley is a hot spot for year-round fishing opportunities. Cottage Grove Reservoir, nestled at the southern tip of the valley, is a popular destination. Before casting their rods, anglers need to be aware of the many weathered fishing advisories that dot the shoreline. Less than 10 miles up the river sits an abandoned mine. It’s peaceful now, but operating from the 1890s to the late 1960s, Black Butte Mine was one of Oregon’s most productive mercury mines. Its legacy still bleeds into the ecosystem today.
Until 2008, elevated mercury levels in the Coast Fork Willamette River and Cottage Grove Reservoir were thought to come from natural volcanic rock and geothermal activity in upper drainage areas. We now know that one of the feeder streams, Furnace Creek, had been running through one of the mine’s abandoned waste material piles for decades. According to the Oregon Health Authority, 50% to 75% of the mercury contamination in the watershed originated from Black Butte Mine.
“The tailings pile was the stream bed for a segment of Furnace Creek. It was amazing that, back in the day when people were running the mine, no one thought that it would be a problem to dump all of the tailings in the middle of the creek and let it erode through,” said David Farrer, a public health toxicologist with the Oregon Health Authority.
In the late 1990s, the Oregon Health Authority identified Black Butte Mine as a site of interest for environmental contamination. Then, in 2010, the EPA added the site to its National Priorities List and stepped in to help with the cleanup, designating the area a Superfund site. A Superfund designation means an area is prioritized by the EPA because hazardous substances pose a significant risk to human health and the environment. There are seven Superfund sites in Oregon, six of which are in the Willamette Valley.
In the mining process, rocks were split into pieces and heated to extract mercury. The contaminated dust and waste particles created entered the watershed. However, mercury being in the water isn’t the public health concern; it’s the fish.
Inorganic mercury from upstream gets deposited and settles into sediments at the bottom of the reservoir. Certain microbes convert inorganic mercury into the toxic form of mercury, methylmercury. Small organisms like plankton absorb this methylmercury, and as larger fish eat smaller ones, the chemical concentrates build up in their tissues. Over time, top predatory fish, such as bass, accumulate the highest levels, creating health risks for both people and wildlife that consume them.
“Cottage Grove Reservoir has some of the highest mercury fish concentrations in the state,” said Bryn Thoms, a hydrologist at the Oregon Department of Environmental Quality.
Extensive cleanup efforts of the tangible materials have been done. The tailing pile at the head of Furnace Creek has been cleaned up and tailings used on roads and driveways have been paved over. However, the problem of removing the mercury remains.
“Mercury is an element, so it doesn’t become anything else. It just sort of stays in the system, cycling around between the fish and the sediment. And even though there’s less input now, there’s not really a way to subtract mercury out of the reservoir at this point,” said Farrer.
“I think that if it was a smaller reservoir, you probably could do a certain amount of sediment excavation. Or you could somehow change the regime of methylation so that you’re not getting as much,” said Thoms. “But it’s pretty difficult and it’s pretty costly.”
With no clear end date for full site cleanup or confirmation that mercury can ever be removed, public education is necessary to keep health risks low.
“For so long, we were told diseases are genetic. And that’s not actually the case. One of the interesting and important things is helping people understand that there are things that can modify disease,” said Diana Rohlman, an associate professor and senior researcher in the Department of Environmental and Molecular Toxicology at Oregon State University and director of the Community Engagement Core at the OSU Superfund Research Center.
“We also don’t want people to feel like they’re to blame if they get a disease. But should people be aware of the fact that they live next to Superfund sites? Yes, they should,” said Rohlman.
Focused on educating the public, Rohlman’s curriculum explained how mercury moves through the environment and its potential impact on public health. But funding dried up and the initial teachers who partnered with the program moved to different schools.
Currently, fishing advisories are the main remaining avenue for public health communication, and they aren’t super effective. There are several reasons for this. Signs may be posted along the reservoir in areas where people don’t fish, there may be a language barrier to understanding, or individuals may simply choose to ignore them.
Sarah Rothenberg runs the Methylmercury Lab at Oregon State University and recently published a paper looking at how recreational female fishers respond to mercury fish consumption warnings at the Cottage Grove Reservoir.
“I think what was most important to me was that women who are fishing in these contaminated water bodies are fishing in not just one, but in two or three,” said Rothenberg.
Licensed female fishers who fish at contaminated water bodies don’t realize that the advisories don’t “reset” at each lake or river. The limits accumulate, so even if women were only taking one fish from Cottage Grove Reservoir, they may still be fishing at several locations and consuming more fish than is safe.
Rothenberg also found that some of the highest-risk populations weren’t represented in her data because they are unlicensed. Those include individuals who cannot afford a license, migrant workers unfamiliar with licensing rules, and Native fishers who are exempt from state licensing requirements.
“The agencies need to partner together,” said Rothenberg.
To improve fish warnings, she argues that Oregon’s Health Authority and Department of Fish and Wildlife should partner to ensure that advisory information is automatically included with fishing licenses and communicated in a unified, easy-to-understand manner.
“The risk is constant. It’s the same risk since the report came out. But awareness about it is hard to keep going,” said Farrer.
Even decades after Black Butte Mine shut down, its mercury still winds through the Willamette Valley’s waterways, silently accumulating in the fish people catch for dinner. Cleanup has removed the piles of tailings, but the real work now is to keep the community informed and educated about the persistent risk.
