Why Ottumwa has avoided water restrictions
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Ottumwa Water Works general manager Tim Albert and a gauge showing the nitrate levels from the Des Moines River in Ottumwa. Photos: Courtesy of Albert
Hi! Welcome to our "Water Cooler Talk" series, where we answer your water quality questions.
A Des Moines resident asks: "Is CIWW/the Des Moines metro the only utility-serviced region that is going on restrictions due to high nitrate levels?"
- "I believe Ottumwa pulls its water from the Des Moines River, too. Are they seeing the same nitrate levels as Des Moines/CIWW? If so, why are they not placing restrictions on users? If they are not, what's happening downstream to make Ottumwa better off than Des Moines?"
Answer: Ottumwa's raw water has averaged slightly fewer nitrates this year than Des Moines', thanks in part to geography.
- The Des Moines and Raccoon rivers, Des Moines' main sources, converge downtown, and then flow into Lake Red Rock before reaching Ottumwa, which is 90 minutes southwest of the capital city, Ottumwa Water Works general manager Tim Albert tells Axios.
- That reservoir acts like a buffer, smoothing out nitrate spikes rather than passing them straight through.
- Ottumwa is also farther downstream, diluting the water from the higher nitrate sources in northwest Iowa, says Michael Schmidt of the Iowa Environmental Council.
By the numbers: Ottumwa's river water has averaged around 10 mg/L nitrate this year, Albert says. The average level coming out to customers has been 7.83 mg/L. The EPA's maximum allowable level for drinking water is 10 mg/L.
- The average source water levels this year for the Raccoon River are 13.27 mg/l, and Des Moines River is 10.75 mg/L, per Central Iowa Water Works.
Plus: Albert says that municipality runs completely differently — Ottumwa has no nitrate removal facility. Instead, it blends river water with a separate, nearly nitrate-free supply from old sand mining pits west of the city.
- The city's treatment plant was also built in the 1960s, when leaders expected much bigger population growth that never happened.
- That left Ottumwa with more capacity than it needs. The 12-million-gallon-a-day plant peaked at just 7.6 million gallons on its busiest day in 2025.
- Most of Ottumwa's water use goes to industry, not residents, which also helps ease the irrigation pressure.
Yes, but: Ottumwa isn't immune to nitrate problems, Albert says. He would like the state to help pay for newer filtration technology, similar to the $25 million Iowa Gov. Kim Reynolds gave to improve Central Iowa Water Works' filtration system.