Wayne County's wastewater treatment plant will soon have to reduce the amount of phosphorus it dumps into the Detroit River.
It's part of the state's plan to lower phosphorus levels in Lake Erie to control cyanobacteria blooms.
Bill Creal is with the Michigan Department of Environmental Quality. He says the new permit for Wayne County will be the same as the permit given to Detroit Water and Sewerage last year, which was more successful at reducing phosphorus than anyone envisioned.
Detroit's new permit is for .6 milligram of phosphorus per liter, down from 1 milligram per liter.
The permit is in place in the spring and summer, which is when cyanobacteria grows.
Creal says Detroit's water system has actually been discharging about .2 to .3 milligrams phosphorus since making the change. Controls put in place include increases in the use of chemicals that precipitate phosphorus out of water before it goes into the river.
Wayne County's treatment plant discharges much less water into Lake Erie, but Creal says it's still a significant amount. The new permit could go into effect as soon as the spring of 2016.
Michigan is also looking at what it can do to reduce phosphorus flowing into Lake Erie from the Maumee River, although Ohio has much more land along the river and will have to do most of the heavy lifting there.