(The Center Square) – Drought conditions in Iowa expanded in June, with streamflow conditions in the Des Moines and Raccoon rivers continuing to decrease, the Iowa Department of Natural Resources reported.
Remedial projects may cost up to $30 million, a cost that will impact consumers’ water rates.
Des Moines Water Works uses the rivers to provide drinking water to about 500,000 people living in the Greater Des Moines area. Last month, it launched its Water Shortage Plan when drought-induced low river levels and “record-breaking customer demand for water” led to a 90% demand on its production capacity.
The record water shortages can amplify water quality problems and water treatment costs, DMWW Chief Operating Officer Kyle Danley told The Center Square.
“It may not be as obvious, but during water shortage conditions there is simply less water in the river system,” Danley said. “The ability of a smaller volume of water to buffer pollutants that may enter the river is diminished. Especially during the summer months, when Harmful Algal Blooms develop, water quantity and water quality issues intersect and make treatment more difficult.”
DMWW is working with the United States Geological Survey to explore the feasibility of drilling wells to use high-quality alluvial groundwater that may be available along the Des Moines River between Hickman Road in Des Moines and Saylorville Lake Dam to address water quality issues.
“Agricultural intensity [in the two rivers’ watershed] aids in creating ammonia, nitrate, algae, cyanobacteria, and cyanotoxins at elevated concentrations in both rivers in Des Moines,” Danley said. “Many times the water treatment plants in Des Moines can handle the pollution. At other times, the concentrations are substantially high and the water treatment plants are barely able to produce safe water for Des Moines residents.”
DMWW reported that nitrate levels in 2020 reached 8.39 mg/L at its L.D. McMullen Water Treatment Plant and 7.7 mg/L at the Fleur Drive Treatment Plant. The EPA’s maximum contaminant level is 10 mg/L. The utility uses source water blending and removal of nitrate through ion exchange to treated water to ensure levels remain below the 10 ppm standard, which it has been able to do since it began nitrate removal in 1992, the report said.
“DMWW vigilantly monitors each river and deploys ‘avoidance’ as a first step in treatment. Once ‘avoidance’ has been deployed, DMWW is forced to treat what we receive in the river,” Danley said. “Again, the margins between successfully treating the water and not are becoming more narrow and more frequent.”
The alluvial wells project will likely cost about $30 million and impact customers’ water rates, Danley said.
“If quality and quantity are found to be favorable, DMWW will apply for regulatory permits and acquire any required easements which will likely take a year or more,” a fact sheet from the utility said.
After the regulatory permitting process, design, bidding, construction, and testing could take another two or three years.
Through the Iowa Nutrient Reduction Strategy, a project of the Iowa State University College of Agriculture and Life Sciences, Iowa Department of Natural Resources (DNR), and Iowa Department of Agriculture and Land Stewardship, aims to reduce Iowa’s annual nitrogen and phosphorus loads by 45%. The team said in the 2018-2019 annual progress report practices to reduce nutrient loss (from land into Iowa rivers) includes planting cover crops, applying fertilizer “at efficient rates,” using animal manure as fertilizer, and installing buffers.