A project to remove contaminated sediments from a harbor on Lake Superior in northern Wisconsin is underway after years of planning and legal battles.
Contractors have started to dredge the bottom of the Ashland harbor, which long has been tainted with cancer-causing pollutants and clogged with wood from shuttered lumber mills as well as cast-off docks, the Milwaukee Journal Sentinel reported.
State and federal regulators have identified Northern States Power Co. of Wisconsin as responsible for cleaning up the pollution.
Officials at the utility, which is a unit of Minneapolis-based Xcel Energy Inc., say the effort could cost as much as $97 million and are asking natural gas customers in its service territory to help pay for it.
The goal of the cleanup is to rid the harbor of polycyclic aromatic hydrocarbons, volatile organic compounds, oil and tar.
A majority of the pollutants cling to wood or have lodged in the sediments.
Lake Superior’s waves can also act like a giant washing machine, re-suspending the oil and tar in a way that can create big plumes of petroleum slicks.
Much of the lake’s pollution can be traced back to a former plant that discharged a tar-like substance while using coal to produce lighting and electricity in Ashland.
“It had a big round tank and this heavy coal tar was dumped into the lake,” said Ed Monroe, a local historian who specializes in the city’s lakefront history.
Jamie Dunn, project manager at the Wisconsin Department of Natural Resources, said there were areas where the tar was “bubbling to the surface — clearly a direct contact risk and a significant groundwater risk.”
Natural Resources Department officials say the pollutants present a health risk to humans, fish and the aquatic life living on the floor of the harbor.
Crews removed contaminated soil on land and captured and cleaned polluted groundwater last year.