(Des Moines, IA) -- Des Moines Water Works has turned on it's nitrate removal facility, due to a higher-than-normal concentration of nitrates in the both Des Moines and Raccoon River levels. CEO Ted Corrigan tells WHO Radio News it's the first time they've had to use the system since 2017. He says a dry summer and fall of 2021,followed by a wet spring this year, has resulted in higher levels.
The system costs up to $10,000 per day to run, but Corrigan says it's factored into their budget so customers will not see an increase in bills.
He says, however, they'd prefer not to run it, and continue to advocate for more agricultural practices which encourage improved water quality.
He says he's heard that there are less than four million acres of cover crops planted in Iowa. Corrigan says in order for such practices to really make a difference for watersheds, the cover crop acreage should be closer to 15 million acres, which is nearly half the state's tillable crop land in Iowa.
The U.S. Environmental Protection Agency’s Safe Drinking Water Standard for nitrate is 10 milligrams per liter (mg/L). Nitrate levels in the rivers and the shallow alluvial groundwater Des Moines Water Works uses are above 9 mg/L. After deploying other strategies, the nitrate removal facility has been activated .
“This is a delicate time – we are at that point where we are monitoring the nitrate level closely, and it is an hour-by-hour decision on which sources of water to use and how to blend the water source in order to reduce nitrate levels,” said Corrigan.
The nitrate removal facility captures the nitrate ions in the water, similar to how a home water softener removes calcium and magnesium ions. Nitrate removal waste is diverted to Des Moines Metropolitan Wastewater Reclamation Authority (WRA) where is treated through controlled biological environments within the WRA facility. In addition, a beneficial reuse product called biosolids is produced for land application on agricultural fields in the Des Moines River Watershed (Polk and Jasper Counties).
“While we are able to do the work downstream to remove nitrate to comply with drinking water standards, there is a financial cost to our ratepayers to do so,” Corrigan said. “The real solution is upstream. The landowners there are the solution-holders. They have the ability to make changes to the way they use their land in order to keep nutrients on the land and in the soil, which is where they belong.”