Water Works switches to DM River to avoid nitrate
Des Moines Water Works is pulling most of the drinking water for its 500,000 customers from the Des Moines River and from shallow groundwater near the treatment plant to avoid running its nitrate-removal system, said General Manager and CEO Bill Stowe.
Stowe said he still fears the utility will have to run the nitrate-removal system this winter when the dilution from recent rains subsides. “Check with me in a week,” he said.
Last year, Water Works for the first time was forced to run the system for an extended period in winter because both the Des Moines and Raccoon had high nitrate levels. The system, which costs upwards of $7,000 a day to operate, was on from Dec. 6, 2014, through March 17 of this year.
That was unprecedented. Typically, nitrate levels fall in winter, when there is less runoff.
Nitrate can suffocate infants at certain concentrations and has been associated with a range of illnesses in adults. Des Moines has one of the world’s largest nitrate-removal plants and is studying how much it would cost to replace the 20-year-old model with a bigger one.
Water Works also is locked into a nationally prominent lawsuit in which it contends that three northwest Iowa counties should be forced to get a federal permit to control nitrate releases from their drainage districts.
The nitrate level in the Raccoon River at Sac City was 17 milligrams per liter today. “That’s pretty alarming,” Stowe said.
The Des Moines River in Des Moines was running at 6.6 milligrams per liter. The drinking water limit is 10.
The nitrate level in the Raccoon River at Sac City has been above 14 milligrams per liter for most of this year, U.S. Geological Survey measurements show. The Des Moines River nitrate level in Des Moines exceeded the drinking standard at the beginning of the year for a while, and again in summer, before falling in August. The level rose to near 10 in September before falling again.
Stowe said last winter both rivers were running well above the limit, and the utility was unable to meet standards by merely blending water from various sources.
The Des Moines River has had detectable levels of toxic algae, another challenge, but Water Works removed that pollutant by making adjustments to its chemical feed, Stowe said.
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Your guide to the Water Works lawsuit
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