Continued high nitrate levels in the Des Moines and Raccoon Rivers have forced Des Moines Water Works to activate its nitrate removal facility in order to keep finished drinking water safe for consumption. Nitrate levels in September, October and November were the highest ever experienced in those months and have required extraordinary efforts by Des Moines Water Works staff. Activation of the nitrate removal facility is the last step available to maintain safe drinking water.
Current nitrate levels are 12.62 milligrams per liter (mg/L) in the Raccoon River and 11.63 mg/L in the Des Moines River. By means of extensive and expensive water treatment, Des Moines Water Works’ finished drinking water currently has a nitrate level of 8.79 mg/L. The Environmental Protection Agency’s (EPA) maximum contaminant level (MCL) for nitrate in finished drinking water is 10 mg/L. Despite the high levels of nitrate in the source waters, Des Moines Water Works’ finished drinking water remains safe for consumption, due to the activation and operation of the costly nitrate removal facility.
Des Moines Water Works began using the nitrate removal facility today to keep finished drinking water nitrate levels below the Safe Drinking Water standard. Prior to starting up the facility, Des Moines Water Works staff managed the fall/early winter high nitrate situation through blending of various water sources, including water from the gallery system at the Fleur Drive Treatment Plant (shallow ground water collector system), Maffitt Reservoir, Crystal Lake and Aquifer Storage and Recovery (ASR) wells.
“Des Moines Water Works staff has employed extensive efforts to mitigate nitrate levels, but because nitrate continues to be introduced in the watershed at high levels, we were left with no alternative but to activate the nitrate removal facility,” said Bill Stowe, CEO and General Manager, Des Moines Water Works.
According to the Iowa Nutrient Reduction Strategy, approximately 92% of nitrate loads enter our water resources through sources that are not currently being subject to any mandatory regulations, despite longstanding legal mandates to address such pollution.
“Continued but unfounded insistence from state leaders that the voluntary approach of the Iowa Nutrient Reduction Strategy is working does not give solace to the 500,000 central Iowans who must now pay to remove pollution from their drinking water,” said Stowe. “Further, the persistent argument that ‘weather is to blame’ for this situation is wrong. Science proves weather and other natural conditions do not create excessive nitrate concentrations. Intensive land use and extensive agricultural drainage systems are the source of the high nitrate in our source waters.”
Raccoon River Des Moines River
September 2014 11.61 mg/L 7.20 mg/L
October 2014 13.23 mg/L 11.15 mg/L
November 2014 13.25 mg/L 11.88 mg/L
Record nitrate levels were reached in 2013, when the Raccoon River reported 24 mg/L and the Des Moines River reported 17.87 mg/L. Throughout the spring and summer of 2013, Des Moines Water Works operated the nitrate removal facility for 74 days, at approximately $900,000 in treatment costs and lost revenues passed on to ratepayers.
In order to ensure that tap water is safe to drink, the EPA prescribes regulations limiting the amount of nitrate levels in water provided by public water systems. The greatest health risk posed by high nitrate concentrations is for infants under six months of age. Nitrate can transform into nitrite in the infant’s body, reducing the ability of the baby’s blood to carry oxygen. This may result in Blue Baby Syndrome. Des Moines Water Works’ finished drinking water nitrate concentration is currently below the level which is indicated to cause these health implications. If you are caring for an infant, you may wish to seek advice from your healthcare provider.