EPA: North Shore 'sheen' possibly linked to Superfund site

An oily substance found earlier this month on the shore of Flathead Lake’s Somers Bay has tested positive for chemicals associated with a former Superfund site located nearby, Environmental Protection Agency officials announced Friday.

Naphthalene and acenaphthene were detected at levels exceeding EPA site-specific standards, according to finalized test results released by the agency Friday. The closely related compounds are associated with the manufacturing processes previously employed at a former BNSF Railway railroad-tie plant in the vicinity of the shoreline “sheen.”

“While there is no indication of widespread contamination along the shoreline or in the lake that would represent a public health risk, these findings underscore the importance of ongoing efforts at the site,” agency spokeswoman Katherine Jenkins said in an email Friday. “EPA has made no conclusions about potential sources, however, these contaminants are potentially associated with former wood treating activities and known contaminants at the BN Somers site.”

Jenkins referred follow-up questions about the extent of the chemicals’ presence to the agency’s Helena-based site manager, who did not immediately return phone calls Friday.

The finding appears to contradict earlier indications that the substance was naturally occurring, per the agency’s preliminary test results.

“The fact that they’re getting those two compounds is, I think, a little more indicative that it probably is coming from that plume from the Superfund site,” Shawn Devlin, an assistant research professor with the Flathead Lake Biological Station, said Friday afternoon. He added, “I think you could take out the ‘potentially.’ I think they are associated with activities on the site. It doesn’t make sense that these two aren’t connected in some way.”

Devlin hesitated to draw any further conclusions without data to indicate the degree to which the two compounds exceeded the standards established under the site’s 1989 Superfund cleanup plan. But he said their presence is consistent with that of contaminants that have been documented in the soils and groundwater at the site.

The tie plant, which operated between 1901 and 1986, was listed as a Superfund site in the 1980s due to the presence of creosote and petroleum-related chemicals in the soil and groundwater beneath the site. It was later removed from the National Priorities List, but is still managed in accordance with the Superfund program through an agreement between the EPA and BNSF Railway, which owns the former tie plant and surrounding properties.

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 Superfund site.

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