For years, local authorities have treated combined sewer overflows (CSOs) with chlorine to kill bacteria in preparation for diverting the overflow following heavy rains away from wastewater treatment plants and into natural water bodies.
The U.S. Environmental Protection Agency has been urging state and local officials to convert combined sewer systems into separate sanitary and stormwater sewer systems.
“Oakland County dumped 2 billion gallons of sewage into Macomb in August storm”“Several hours after the Aug. 11  storm, the polluted Red Run Drain in Warren was still about 20 feet above its normal level.”
Thereafter, pathogens, toxins and nutrients originating in household wastewater would go to a wastewater treatment plant for removal while the heavy volume of rainwater would flow separately, directly into lakes and streams. Cities like Lansing and Grand Rapids have undertaken such conversions.
Presently, Nash sends combined storm and sanitary effluent from the giant Kuhn Retention Basin in Madison Heights to a wastewater treatment plant in Detroit.
If heavy rainfall threatens to overwhelm the treatment plant, Nash partially treats the combined fluids with chlorine to control pathogens such as bacteria and sends the deluge into Red Run, through Macomb County to the Clinton River and Lake St. Clair.
But the sanitary sewage component contains the nutrients like phosphorus that are found in human waste. Those nutrients generate algal blooms, some with toxic potential, that contribute to the degradation of Lake St. Clair.
In other words, Nash seems content to pass on to Lake St. Clair the pollutants in the waste of hundreds of thousands of people rather than the separated stormwater running off roofs and pavements.