From the Daily Iowan
An undisclosed amount of sewage bypassed the North Liberty treatment plant on the morning of Aug. 25 and entered the Iowa River, said Josh Sobaski, an environmental specialist for the Iowa Department of Natural Resources.
The news came from North Liberty wastewater-superintendent Dave Ramsey, who reported the discharge occurred at 9:17 a.m. Aug. 25, Sobaski said, adding that he had not received any indication that the spill had been stopped as of 5 p.m. Sunday.
North Liberty Mayor Tom Salm said he was also unaware of whether the discharge had been stopped as of 8:30 p.m. Sunday.
Alan Foster, a Natural Resources information specialist, attributed the spill to the heavy rain in the area, though Sobaski said that North Liberty is known "to have had challenges with bypass issues in the past."
"[Bypasses] are a necessary evil," Foster said.
Though bypassing sewage into the water supply is not a desirable option, it beats the alternative of having sewage backups in the basements of North Liberty homes, he said.
Foster said even the best sewage-treatment plants must allow bypasses when rainfall gets especially heavy, although they are expected to have a plan in place to minimize the ill effects of the release.
Sobaski said the sewage was somewhat diluted, though he did not say to what extent the discharge had been sanitized.
Salm said that the sewage was probably diluted more than halfway before it spilled into the river, although he couldn't give an exact percentage. The treatment facility has been operating at 120 percent capacity over the last several weeks, he said.
Ralph Wilmoth, the director of the Johnson County Public Health Department, said the presence of sewage in drinking water supply increases potential for "fecal oral route transmission diseases," including salmonella and E. coli.