About 4.7 million gallons of untreated sewage was diverted into the Stillwater River in a 20-hour span after the Memorial Day tornadoes, Montgomery County officials told the Dayton Daily News.
County sewer officials had to divert wastewater directly into the Stillwater River after two lift stations lost power on Memorial Day.
The existing river water and additional rainfall diluted the sewage and moved it downstream through the Great Miami River, said Dina Pierce, an Ohio Environmental Protection Agency spokeswoman.
For that reason, the river was not sampled for contamination, she said. Ohio EPA officials might require sampling for water quality depending on the severity of a given overflow, size of the receiving stream and utilization of the water downstream, she said.
The entire wastewater system handles an average of 35 million gallons per day, equivalent to about 53 Olympic-sized swimming pools. The total number can vary with heavy rain, which can increase overall flow, said Brianna Wooten, Montgomery County spokeswoman.
Pierce said that because the last discharges from the county were on May 30, enough time had elapsed by Wednesday to lift the precautionary advisory recommending people avoid recreational activities on the rivers.
Sewage discharges contain bacteria, viruses and other microbes, the Ohio EPA said. These organisms can be a public health risk, which led to the advisory to stay out of the rivers following last week’s storms.
The state prohibits sanitary sewer overflows. But in emergency situations, Pierce said, “there are times when a discharge from a sewer to a stream may be necessary to prevent raw sewage backups into homes and businesses.”
A local water expert told the Dayton Daily News the sewage dump could potentially kill fish and other wildlife. David Rager, a former director of the Greater Cincinnati Water Works, said the overflow also could increase bacteria and algae downstream.
“There will be impacts,” said Rager, the current American Water Works Association president who last week advised Dayton City Manager Shelley Dickstein during the city’s water outage and boil advisory.
Wooten said the county could not address Rager’s concerns, but said she believes Public Health — Dayton & Montgomery County and the Ohio EPA “have made it clear that the risk (is) over in our area.”
Springboro City Manager Chris Pozzuto said he was not concerned by the sewage dump. Springboro’s water is drawn from the aquifer and “is not subject to surface water,” he said.
Wooten said all lift stations are back to normal operations except for the Stillwater facility. Sewage there is being pumped directly into the sanitary sewers using bypass pumping.
The Dayton Daily News has partnered with the Dayton Foodbank to deliver food and water throughout the community in coming days. To donate to the effort, visit daytondailynews.com/tornadorelief.