Mystery sludge rings Miller Bay on Lake Osakis and residents aren't happy

OSAKIS, Minn. — Along a half-moon of cabins lining Miller Bay on Lake Osakis, a gloopy dark sludge covers the waterfront, preventing swimming and boating.

Residents are trying to figure out where the sludge came from.

“There’s 10-15 cabins in that little stretch that just had their lakeshore destroyed,” said Janice Hauri, one of the cabin owners. “It was so thick we couldn’t walk through it. The muck was so deep that you would sink up to a foot.”

Hauri gave pictures to Forum News Service showing her dog running along a sandy beach in a previous year. In 2019, she said, the water level was so high that it splashed muck over the rocks in front of her cabin. In 2020, the water level dropped, exposing muck like she’d never seen in the decades she has spent summers there.

She was a child when her parents bought the place in 1985.

“It used to be a great place to be,” she said. “Now it’s more like a swamp.”

She also said she noticed that the zebra mussels that once clung to her dock are no longer present, and wonders if the sludge killed them.

Interviews with several experts and neighbors reveal a variety of possible reasons for the sludge. Experts say the problem could stem from one or several causes.

Six doors down from Hauri’s cabin, Judicial Ditch No. 2, or JD2, empties into Miller Bay on the north side of the lake, which sits in Todd and Douglas counties in west-central Minnesota.

The ditch leads upstream to two sediment ponds built to keep pollutants and sediment from entering the lake.

In March 2019, the Sauk River Watershed District dredged those ponds, hauling 22,000 tons of sediment, or more than 1,700 dump truck loads to a farm field a half-mile to the southwest of the ponds, said district administrator Scott Henderson. He said the sludge was surrounded by blockades to prevent it from leaking out until the farmer could plow it in, and that two inspections, one in February 2019 and the other in March 2019, found no erosion.

"We never saw sediment leaving the site," he said. "If we would have observed it, we would have corrected any issues out there. We are an agency with a mission of improving water quality. We would not do something to impair the water of Lake Osakis or any other lake within our boundary."

Neighbors point to the timing of the work on the ponds, and say they suspect the blockades around the sludge didn’t work, and that a subsequent rain ended up washing it back into their bay.

“They did something to try to prevent the stuff from washing back in but it went right underneath it,” Hauri said.

Steve Malz, whose cabin sits two doors down from Hauri’s, said he’s been on the lake for 28 or 29 years. He used to duck hunt on the water and put waders on for fly fishing. Bulrushes once covered the bay, he said, but they started slowly diminishing after the sediment ponds were built.

DNR area hydrologist Mark Anderson visited the bay this summer and hasn’t yet started looking at possible causes and doesn’t know if the dredging is to blame.

“If they let water out, if that’s causing some type of sedimentation in the basin, then we can probably justify extrication or removal of that sediment,” he said. “If we can’t be certain, then it gets really difficult to go in and start digging out lake bottom.”

Long-time residents say bulrushes once proliferated in Miller Bay. These tall, native plants grow in shallow water and keep waves from washing sediment up on shore.

But they have largely vanished in recent years, and the residents say they don’t know why.

Jerry Wendlandt, DNR aquatic plant management specialist for the region that includes Lake Osakis, said bulrushes are sensitive. They can die off from repeated boat traffic, even at trolling speeds, from glyphosate applications, and when water levels are too high.

Landowners can request permits to clear a 15-foot wide swath through cattails and bulrushes, and he will usually approve them. He chooses swaths with care, figuring out which path which will least disrupt water quality, fish habitat and shoreline integrity.

The DNR hasn’t received a permit request for those swaths in at least 10 years on Miller Bay, he said, which could mean the bulrushes had dwindled to the point where they didn’t pose an obstacle, or that boaters crossed over them wherever was most convenient. It’s completely legal to do that, as long as it’s not done intentionally to destroy native plants.

The fact is, Wendlandt said, is that bulrush roots bind up sediment on the lake bottoms, and also blunt the force of the waves.

Without them, landowners will see more shoreline degradation.

“They are very hard to get reestablished once they’re destroyed,” he said.

In a May 24, 2020, letter published in the fall Osakis Lake Association newsletter, Todd County Soil and Water Conservation District manager Deja Anton reported that she has received water quality complaints from people living on four lakes in Todd County.

“I have received many calls over the past two weeks regarding lack of lake transparency, murky waters, little fish action, brown foam and muck washing up on shores, and large amounts of slime and varying algae types showing up in the lake,” she wrote. “People are fearing for their lake’s health and want to know what is causing this issue!”

The problem was not isolated to Todd County, she said, as she has discovered that lakeshore owners in Pope County and in the Twin Cities also had the same concerns.

She said the problems appeared to be caused by the wet fall in 2019, when wetlands and soil were brimming with water. This spring, ditches were filled with water, and an early, rapid ice-out led to waters carrying a variety of diverse, nutrient rich organic material and sediment.

However, Hauri said she believes the Miller Bay problem is different.

“I'm confident our muck came from the dredging project for many reasons,” she said. “No one else on the entire lake has this issue except us. We have friends in many different areas of the lake, none of which had this issue.”

She added, “We get high water a lot in the spring, many times worse than it was two years ago, and this did not happen any of those times.”

The Miller Bay neighbors say they have not been able to find answers to their questions, and that often, people in local and state agencies won’t return their calls.

“We’ve had low water before and not like this year,” Malz said. “They’ll say it’s the lowest it’s been since 1935. They got all kinds of excuses.”

They would like to be able to use their bay again.

“I just want them to remove the muck,” Hauri said. “I want my sandy beach back.”

Bryan Van Den Einde, a St. Cloud resident, and his family bought a cabin on Miller Bay in 2017 because they liked the level lot, the location and the fishing. It was their first lake home. The first summer was fine, he said. They had to take their boat out in July because the water levels were getting so low. The problem worsened in the following year, as thick weeds sprang up in the bay. He would like to see the state take care of the problem, maybe even raising funds through user fees on the lakes.

“The kids didn’t want to go to the lake. Nobody wanted to go to the lake,” he said. “What’s the point of having a lake place where you can’t use the lake?”