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WUWM's Susan Bence reports on Wisconsin environmental issues.

Menomonee River oil spill causes concerns for Milwaukee waterways

On December 3, Komatsu reportedly discovered what the company originally thought was a minor oil spill from its Menomonee Valley plant into the river.
Susan Bence
On December 3, Komatsu reportedly discovered what the company originally thought was a minor oil spill from its Menomonee Valley plant into the river.

Editor's Note: This story was updated on Dec. 14, 2021 at 4:05 pm.

Komatsu issued an official media statement Dec. 13, 2021 stating:

“At this time, we estimate we have been able to recover about 80% of oil residue on Milwaukee’s waterways, and we are working rapidly to address the remainder.”

The oil is reported, according to the statement, ”to be a combination of spent cutting, hydraulic and lubrication oils generated from our manufacturing process.”

A company spokesperson told WUWM “our hired contractors have been out there with boats – we just don’t have Komatsu boats.”

Komatsu reports the following cleanup activity over the last several days:

- Friday, 2 boat crews deployed.
- Saturday, 3 boat crews deployed.
- Sunday, 2 boat crews deployed.
- All three days, a land crew access oil pockets and sheen at difficult locations along shorelines with a vacuum truck.
- Monday, 4 boats crews deployed.

The company said all efforts to address the spill “are being considered and aggressively implemented."

WUWM's earlier story published on Dec. 13, 2021 follows below.

Last week, word spread that a concerning amount of oil had made its way into the Menomonee River.

It was later learned that Komatsu, the mining company, had discharged 400 gallons of used oil through a stormwater outfall near the company's Menomonee Valley site.

The outfall empties directly into the river.

While Komatsu has taken responsibility for the spill and the clean up, some worry about removing the oil. There are also concerns about its potential impact on the river and the life in and around it.

That includes concerns from Milwaukee Riverkeeper Cheryl Nenn. She stood along the Menomonee River Friday, just east of the Brewers’ stadium, and looked straight into the storm sewer that delivered the equivalent of eight 50-gallon drums of oil into the river one week earlier.

"We are east of the American Family stadium and just south of the pedestrian bridge that most people use to walk to games," Nenn said. "We're a few miles upstream from the confluence with the Milwaukee River...the [spilled] oil is all the way down from this site through the lower Menomonee and has spread in a pretty large section of the Milwaukee River."

If anyone knows Milwaukee’s rivers, it’s Nenn. Her job title is riverkeeper and she coordinates ongoing water quality monitoring on the Milwaukee, Kinnickinnic and Menomonee rivers.

When people notice something weird going on, they often call Nenn. This spill was no different.

“We actually started getting calls on Monday [Dec. 6] about oil sheen on the Milwaukee River and worked with the City of Milwaukee," Nenn said. "And looking at stormwater pipes and went to look to see if oil was coming from tour boats that are still in the water...there aren’t many boats left in the water."

Nenn said it wasn’t immediately clear where the spill started, because of Lake Michigan’s influence.

"The lake is often pushing water upstream. If the wind is coming from the east or northeast, you get sort of this sloshing back and forth of the lake and based on the wind, you can get quite a significant current that pushes upstream," Nenn said.

In this case, the lake is pushing spilled oil with it.

Komatsu issued a release stating that on Friday, December 3, saying "our staff….became aware of what we thought at that time was a relatively small spill of waste oil from a container.” Clean up procedures, the statement continues, began immediately and Komatsu reported to the regional EPA office and the Wisconsin Department of Natural Resources.

An agency spokesperson said the DNR received notification on December 4 “of a petroleum sheen on the Menomonee River.“

The DNR said Komatsu has hired environmental response companies to perform cleanup on its behalf.

A Komatsu spokesperson told WUWM the company “immediately began cleanup upon becoming aware of the spill” and that clean up includes vacuuming oil.

Cheryl Nenn worries time and weather are working against cleanup.

“I had heard boats would be on the river [Thursday] and didn’t see any. But I’m guessing they’re going to need to get out onto the river with some sort of equipment that can vacuum that oil up because I don’t think absorbent pads and other things will probably work very well at this point.” Nenn said.

WUWM's Susan Bence and Nenn looked at some absorbent material incorporated into the boom that stretches across the outfall where the spill met the river.

Susan Bence
Photo taken December 10 of boom at the stormwater outfall where the oil entered the Menomonee River. Cheryl Nenn says a crew had replaced the boom one day earlier.

"I can tell here — there is oil getting past the boom, unfortunately. They did replace this yesterday, we were out here, and they put a new one in. The problem is, it's very hard to deal with these types of spills, which is why prevention is key," Nenn said.

Nenn worries about immediate impacts to birds and waterfowl.

nenn 2.jpeg
Milwaukee Riverkeeper
This oil-covered goose was found near City Lights Brewing downstream from the spill site.

“There was a story in the [Journal] Sentinel about a snowy owl that was covered in oil, which I’m fairly confident came into contact with this product and we did find a few geese yesterday that were covered with oil. I was here yesterday and there were a bunch of mallards playing in that back water, they like kind of slow water. I was trying to clap and shoo them away and they mostly ignored me,” Nenn explained.

Nenn said there’s much more to be learned, including exactly what type and how much oil was spilled. Despite the unknowns, the riverkeeper fears the ripple effects of oil that makes its way down to the river’s bottom of the food chain.

“We’re definitely concerned about long-term impacts to the macroinvertebrates, the little critters on the bottom of the river, and the fish and the birds and humans eating the fish,” Nenn said.

She said anglers love this stretch of the Menomonee.

“If you come out here in the spring and fall, there’s normally dozens of fishermen lined up in here catching salmon and trout,” Nenn said.

After the initial conversation with Nenn, a couple of things happened.

nenn 7.jpeg
Milwaukee Riverkeeper
Riverkeeper Cheryl Nenn says oil has made its way into manmade nooks and crannies along the river, places where birds and waterfowl often seek shelter during the winter.

A Komatsu representative had a lengthy conversation with Nenn’s boss, Jennifer Bolger Breceda, inviting Milwaukee Riverkeeper to provide input throughout the cleanup process. The company pledged to cover damage costs and increase monitoring efforts.

Later, wind and rain buffeted the region, thwarting clean up efforts some believe should have come sooner.

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Susan Bence entered broadcasting in an untraditional way. After years of avid public radio listening, Susan returned to school and earned a bachelor's degree in Journalism from the University of Wisconsin-Milwaukee. She interned for WUWM News and worked with the Lake Effect team, before being hired full-time as a WUWM News reporter / producer.
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