Torrential rains alleviate drought but cause wastewater discharges • Iowa Capital Dispatch

Drought conditions in Iowa have improved to their least severe in about two years thanks to abundant rainfall in recent weeks, according to the U.S. Drought Monitor.

In a Thursday report, all “severe” drought in the northeast part of the state was downgraded to “moderate,” the lowest drought classification.

The last time there was no severe drought in Iowa was March 2022.

About a third of the state is still at least abnormally dry, and about 21% has moderate drought. The latest Drought Monitor report did not take into consideration all of the precipitation from severe weather that swept the state on Tuesday.

Heavy rain leads to wastewater bypasses

About 40 cities reported wastewater bypasses from their collection systems that day, according to the Iowa Department of Natural Resources.

“The city received 5 inches of rain and was forced to bypass from manholes,” a report about Newton in central Iowa said.

Old or poorly maintained sewer pipes — along with antiquated systems that purposefully carry wastewater and stormwater together — can be inundated by heavy rain.

Some cities deliberately pumped wastewater out of their systems to avoid sewer backups into basements, DNR records show. In others, the wastewater overflowed from their treatment systems.

Those bypasses can result in untreated or partially treated wastewater going into the state’s streams. On Wednesday, the DNR warned people to avoid floodwater that could be contaminated.

The department said it has received more than 130 reports of bypasses since the start of April.

The statewide average precipitation was 4.16 inches that month, which is about a half inch more than normal. Average rainfall so far in May totals more than 6 inches, according to Iowa State University data.