Article courtesy of The Des Moines Register | Shared as educational materials | November 24, 2014 |
Treatment processes at Des Moines Water Works have switched into high gear to keep up with water nitrate levels that climbed over the weekend in the Raccoon River.
Nitrate levels in the Des Moines and Raccoon rivers have reached recent historic highs for this time of year, according to Bill Stowe, CEO and general manager of Des Moines Water Works.
Numbers from the waterworks show nitrate levels peaked in the Raccoon River for the month of November on Saturday at 14.47 parts per million. That number dropped to 13.73 Monday. Nitrate levels in the Des Moines River dropped from 11.9 Friday to 11.39 Monday.
Health risks can begin once nitrate levels exceed 10 parts per million, according to the U.S. Environmental Protection Agency.
Higher concentrations of nitrates are more common in the spring when excessive rain washes unused fertilizer from farm fields into streams.
Stowe said the contamination levels this month could require waterworks to operate a costly de-nitrification process for water purification later this week.
“We’ve never seen this big of concentrations this late in the season,” Stowe said Monday morning.
He said treated water is currently safe to drink because it is undergoing more extensive treatment with a “gallery system” that utilizes river banks and other natural processes.