MONROE (AP) – Efforts in Michigan to cut down on the pollutants feeding algae in Lake Erie have been showing signs of success, state officials say.

This includes changes to reduce farm runoff and the amount of phosphorus that comes out of Detroit’s wastewater plant and makes its way into the lake, officials said this past week.

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The phosphorus going into the lake from the River Raisin, a tributary in southeastern Michigan, has been cut in half over the last seven years, said Jamie Clover Adams, director of the Michigan Department of Agriculture and Rural Development.

She credited new farming practices such as buffer strips and drainage controls for the change.

“I think that shows voluntary practices work,” Clover-Adams said. “Most of the conversation you’ll hear is that you can’t do this with voluntary measures; you have to regulate agriculture.”

Algae blooms that are linked to phosphorus from farm fertilizers, livestock manure and sewage treatment plants have become an annual problem in the western third of the lake. Toxins from the algae contaminated the water supply in Ohio for Toledo and its suburbs, including those in southeastern Michigan, just over ago.

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Ohio, along with Michigan and the Canadian province of Ontario, agreed in June to sharply reduce the amount of phosphorus flowing into western Lake Erie within the next 10 years.

Some researchers have questioned whether that can happen without strict new rules on farmers, wastewater plants and septic systems.

Wastewater discharge limits put in place by Michigan in 2011 have lowered the phosphorus amounts released by Detroit’s treatment plant by half or more, said William Creal, water resources chief for the Michigan Department of Environmental Quality.

He said he’d like to see Ohio lower phosphorus limits for normal operating discharges from wastewater treatment plants to the same level Michigan has set.

Heidi Griesmer, a spokeswoman with the Ohio Environmental Protection Agency, said the state has tougher restrictions on certain plants “on a case-by-case basis, based on data.”

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