Dams may power a stop harmful algal blooms in urban lakes, expert says

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Jim and Melinda O’Neill’s property overlooks the east end of Belleville Lake. They don’t boat or fish on the lake, but enjoy the view.

Elinor Epperson

Jim and Melinda O’Neill’s property overlooks the east end of Belleville Lake. They don’t boat or fish on the lake, but enjoy the view.

Capital News Service

LANSING — Like clockwork, Ford Lake and its downstream neighbor, Belleville Lake, turn bright green every summer due to harmful algal blooms.

The lakes, near Ypsilanti, have struggled for decades with phosphorus pollution that spurs algae growth. The quest for a solution is familiar to urban lake communities across the Great Lakes region.

But a hydroelectric dam that separates the two lakes can be used to stop the algal blooms in their tracks, one expert says.

“Maybe it’s not pristine, but it’s certainly a heck of a lot better than it used to be,” said John Lehman, a professor of ecology and limnology at the University of Michigan. He found that the Ford Lake Dam can mix the eutrophic water to prevent the oxygen depletion that causes algal blooms.

Preventing blooms before they start

The Environmental Protection Agency says that neither lake is suitable for swimming and fish from both are unsafe to eat. Excessive phosphorus keeps oxygen levels lower than needed to support the ecosystem.

Lehman recommended that Ypsilanti Township periodically open the floodgates at the bottom of the dam. With enough water flowing through those gates, the water in the lake will mix and provide a steady dose of oxygen to the lake’s sediment, he said.

Lehman and the township tried the method in 2008.

“We wound up being able to improve the condition of the lake really measurably,” he said. But both lakes continue to bloom each year due to persistent high levels of phosphorus.

For decades, state and local agencies studying the lakes have argued that high phosphorus loads come from external sources, such as Ann Arbor’s wastewater treatment plant upstream, and surrounding lawns fertilized with phosphorus.

Lehman disagrees. He says it’s already trapped in the sediments.

“There’s times when the lake exports more phosphorus than it takes in,” he said.

The usual suspects

Lehman has studied Ford Lake’s phosphorus levels for decades. He found that levels dropped after local and state regulations restricted phosphorus in lawn fertilizer.

Those regulations grew out of rising awareness of the harm from excess phosphorus. Stormwater collects phosphorus-rich fertilizer used on residential and commercial lawns, taking it to the nearest water body. The extra phosphorus can lead to harmful algal blooms in the summer.

Belleville Lake benefits from changes to Ford Lake, as a good portion of its phosphorus comes from the other lake directly upstream, Lehman said.

Jim O’Neill, who lives on Belleville Lake, said he suspects other residents still use fertilizer with phosphorus. The township has posted reminders about fertilizer bans, but the regulations are difficult to enforce.

“Sometimes you’ll see stuff going into the lake that shouldn’t be in there,” O’Neill said. 

But Lehman maintains that the amount of phosphorus entering the lakes isn’t the main culprit.

What about wastewater?

The other external source of excess phosphorus is Ann Arbor’s wastewater treatment plant. 

The state dictates the maximum amount of a contaminant that can enter a water body without decreasing its water quality, and the Department of Environment, Great Lakes and Energy reports that the plant’s phosphorus output has consistently fallen below those limits.

Lehman said he doubts sewage overflows are a major factor in Ford Lake’s phosphorus. The largest spill in recent history at Ann Arbor’s plant – a 13-million-gallon release of partially treated sewage during the August 2003 blackout – didn’t induce an algal bloom.

“That was like 10 times the amount of phosphorus that came down [the river] in three days,” he said. That’s “more than you would ordinarily get in the whole month.”

Despite these findings, phosphorus in both lakes exceed the state’s limits every year.

Lehman found that most of the phosphorus causing harmful algal blooms is released from sediment already present in the lake, not external sources.

“It doesn’t matter how much is coming down the river,” he said. “It’s just what happens in the internal dynamics.”

Midwest soil is already rich in phosphorus, which releases from lake sediment when there’s insufficient oxygen in the water, he said. The excess phosphorus feeds the growth of toxic cyanobacteria, which bloom to create a thin green layer on top of the water.

Algal blooms are a routine part of summer for residents on both lakes, said O’Neill’s wife, Melinda O’Neill.

“We get to see a lot of the green [blooms]…it looks like [an] oil slick on top,” she said.

Between 2022 and 2023, residents reported 23 green algae slicks on Ford and Belleville lakes to the Department of Health and Human Services. Testing found toxic byproducts of the bloom at only four locations. Blue-green algae was verified at all but one location.

But the O’Neills haven’t noticed much contamination in nine years living on Belleville Lake. Melinda said other residents complain about the lake’s water quality on Facebook, but the O’Neills only notice an occasional “fishy” smell during the summer. Otherwise, the family enjoys the view of the water and lakeside living.

“It’s like decompressing after a hard day’s work,” Jim O’Neill said.

Ypsilanti Township has continued to use Lehman’s recommended method to mix Ford Lake’s water. But it comes at a cost.

Ford Lake Dam generates electricity that the township sells to Detroit Edison, the area’s power company. Opening the floodgates diminishes how much electricity the dam generates, resulting in a revenue loss of $10,000 to $30,000 per year for the township.

Ann Arbor and Ypsilanti Township recently agreed to update how they manage phosphorus from wastewater in the river, including Ford and Belleville lakes. Officials representing both municipalities said the agreement is not yet finalized but is moving forward.

Robert Kellar, a communications specialist for Ann Arbor’s public services administration, said the city hopes to address the “difference of opinion” about the source of excess phosphorus.

Lehman has documented the debate in his research papers over the years. Disagreements about the lakes’ management “suggest that acceptable recreational water quality can come at a quantifiable price,” Lehman wrote in 2014. 

Residents and local governments have to decide what price they want to put on better water quality in their lakes, he said.

Elinor Epperson and Daniel Schoenherr write for Great Lakes Echo

The Ford Lake Dam was built in the 1930s to produce hydroelectricity for a nearby Ford auto plant. Ypsilanti Township now sells the electricity it generates to DTE Energy

Elinor Epperson

The Ford Lake Dam was built in the 1930s to produce hydroelectricity for a nearby Ford auto plant. Ypsilanti Township now sells the electricity it generates to DTE Energy

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