Historic Nitrate Levels in Des Moines Water Works’ Source Water
Monday, May 13, 2013
Nitrate levels in Des Moines Water Works’ source water reached historic levels last week, at 24 milligrams per liter (mg/l) in the Raccoon River and 17.87 mg/l in the Des Moines River. Currently at Des Moines Water Works’ river intake locations, the Raccoon River is reporting 21.04 and the Des Moines River is reporting 17.56 mg/l; however, higher numbers are being seen upstream. This new record follows the continued upward trend of nitrate concentrations since fertilizer use and increased row-crop agriculture began in the mid-1960s. It has been calculated that last week’s nitrate load surpassed last year’s entire nitrate load.
Through extensive and expensive water treatment, Des Moines Water Works’ finished drinking water currently has a nitrate level of 7.5 mg/l. The Environmental Protection Agency’s (EPA) maximum contaminant level (MCL) for nitrate levels in finished drinking water is 10 mg/l.
In 1991, Des Moines Water Works built a $3.7 million Nitrate Removal Facility, which costs approximately $7,000 per day to operate. The facility has not been activated since 2007. Des Moines Water Works activated the Nitrate Removal Facility last Friday to keep finished drinking water nitrate levels below 10 mg/l. Prior to starting up the facility, Des Moines Water Works staff managed the situation through blending of various water sources, including water from the Gallery (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 changes are not occurring in the watershed, we were left with no alternative but to activate the expensive Nitrate Removal Facility,” said Bill Stowe, CEO and General Manager, Des Moines Water Works.
Nitrate from fertilizer enters our water resources through run-off and agricultural tile drainage systems.
“The optimal solution to prevent nitrate concentrations from entering our source water is through watershed protection programs and good land management practices,” said Stowe. “However, the recently published Nutrient Reduction Strategy is inadequate in that it lacks vision, goals, measurable outcomes, or timelines for agricultural (non-point) discharges. Without significant action, Des Moines Water Works will be forced to continue treating degraded source waters, and our customers will continue to pay for that extensive treatment in their rates.”
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 that will cause these health complications. If you are carrying for an infant, pregnant or have specific health concerns, you may wish to consult your doctor.
About Des Moines Water Works
Des Moines Water Works (DMWW) is a municipal water utility serving the citizens of Des Moines and surrounding communities - approximately 500,000 customers. DMWW is an independently operated public utility with a commitment to leading, advocating and investing today and in the future to deliver water you can trust for life.
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