Initial tests show no human-health risk from lake 'sheen'

An oil-like substance that produced an unusual sheen along a stretch of Flathead Lake’s Somers Bay shoreline earlier this month does not pose any immediate human-health risk, according to preliminary test results by the Environmental Protection Agency.

Katherine Jenkins, a spokeswoman for the EPA’s regional office in Denver, said the agency expects to finalize those results this week. Neither those results nor samples tested by BNSF Railway indicate where the substance originated, although both the agency and the company say it is likely naturally occurring.

First reported by a Somers resident on May 2, the EPA and BNSF began investigating the “sheen” due to concerns that it could be related to the nearby Somers Tie Plant Site, a former Superfund site on land owned by the rail company. The site was taken off the National Priorities List in 1992, but is still managed in accordance with the federal Superfund program under an agreement between the EPA and BNSF.

In an emailed statement sent last Friday, Jenkins said the federal agency’s analysis indicates “low-level detections of volatile organic compounds and semi-volatile organic compounds” in the samples.

“They can be naturally forming or they can be from a chemical” contaminant, she added in an interview Monday. “Basically, it just tells us that it’s not an immediate threat, and that obviously it’s still a safe area.”

Volatile organic compounds, commonly referred to as VOCs, cover a range of chemicals including natural aromatics found in essential oils, as well as toxic pollutants, said Shawn Devlin, an assistant research professor at the University of Montana’s Flathead Lake Biological Station.

“It’s a broad group of compounds that essentially could be really bad, or could be completely inert,” Devlin said Friday. “It could be that it’s just a natural byproduct of the microbial community that’s in those sediments around where they’re finding it.”

BNSF also released a statement regarding its own sample testing last week, with similar results.

“Very low levels of fuel-related or constituents from sources that could be plant- or petroleum-derived were detected,” company spokesman Ross Lane said in a May 9 email. “The source of those contaminants is unknown.”

Neither test results shed any light on what type of volatile organic compounds were present, or whether they are consistent with the contamination plume beneath the former railroad tie plant. Jenkins said the agency has not decided whether it will conduct additional testing to determine the source of the material.

The tie plant, which operated between 1901 and 1986, was listed as a Superfund site in the ‘80s due to the presence of creosote and petroleum-related chemicals in the soil and groundwater beneath the site.

A cleanup plan for the site was finalized in 1989, and the site was de-listed in 1992 following the start of remediation of contaminated groundwater and removal of soil where tie plant operators historically dumped creosote and other waste from the manufacturing process.

While that underground pollution plume still exists, the agency’s project manager for the Somers site, Roger Hoogerheide, said the past three decades of hydrological studies at the site show the groundwater moving in a northeast direction.

“Given how the lake is managed, with that raising and lowering of the lake, we don’t see groundwater migrate toward the lake, we actually see it migrate away from the lake,” he said.

Given where the sludge ponds were located, he said it’s unlikely the contamination is related to the oily material observed on the lakeshore, which he theorized could be due to a combination of biological processes and an “abnormally high” water table.

“I think additional investigations need to be done to confirm that, but that’s kind of what’s in the back of my head, I’m thinking,” he said.

There are no immediate plans to expand those investigations, but EPA officials said they’re still evaluating possible next steps with BNSF and the state Department of Environmental Quality.

Hoogerheide asked that residents contact him at 406-457-5031 to report any more unusual substances reappearing along the shore.

Reporter Sam Wilson can be reached at 758-4407 or by email at swilson@dailyinterlake.com.