DNR: 2 million gallons of diluted wastewater went into Des Moines River

By: - March 23, 2022 2:14 pm

About 3,500 gallons of diluted wastewater poured per minute from a Des Moines pump station overflow pipe into the Des Moines River on Tuesday. (Photo by Tom Atkinson/Iowa DNR)

A wastewater pipe break near Birdland Park in Des Moines caused about 2 million gallons of untreated wastewater — diluted by stormwater that is transported by the same system — to leak into the Des Moines River on Tuesday, according to the Iowa Department of Natural Resources.

The break was first noted in the underground, pressurized pipe about 9:45 a.m.

“When that pipe split, it was like a water main break, so it shot water out of the ground,” said Tom Atkinson, a senior environmental specialist for the DNR.

City workers halted the flow through the pipe within the hour to repair it, he said, but that caused a pump station several blocks away to overflow into the river until about 9:15 p.m. when the pipe had been mended.

The station has an overflow pipe that discharges directly into the river. An estimated 3,500 gallons of diluted wastewater flowed through it each minute.

The leak created a murky plume in the river just north of downtown Des Moines, Atkinson said, but the environmental effects were muted because the river is so large. He did not notice any dead fish.

The DNR advised people who had contact with the river Tuesday to wash their hands and any fish they might have caught from it.

The leak happened downstream from a Des Moines Water Works intake, so it did not affect the metro area’s drinking water.

Des Moines is among a handful of cities in Iowa with combined sewer systems, meaning they transport wastewater and stormwater runoff in the same pipes. Such systems are prone to leaking untreated wastewater into waterways during periods of excessive rainfall or melting snow, when the influx of stormwater overwhelms their capacities.

Excessive stormwater was not the cause of the leak near Birdland Park, Atkinson said. Less than an inch of rain fell in Des Moines on Tuesday, according to the National Weather Service. It’s most likely the pipe failed because it is old, he said.

Des Moines has been working for more than a decade to separate the combined systems. A DNR report from 2008 estimated it would cost hundreds of millions of dollars to do so. City officials did not immediately respond to a request to comment about the projects.

A project to separate the systems southwest of Drake University, stretching down to Ingersoll Avenue, is expected to finish this year, according to the city’s website.

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Jared Strong
Jared Strong

Senior reporter Jared Strong has written about Iowans and the important issues that affect them for more than 15 years, previously for the Carroll Times Herald and the Des Moines Register. His investigative work exposing police misconduct has notched several state and national awards. He is a longtime trustee of the Iowa Freedom of Information Council, which fights for open records and open government. He is a lifelong Iowan and has lived mostly in rural western parts of the state.