Drainage blamed for nitrate woes in Iowa
Dec. 17, 2014, Des Moines – A dense network of subsurface drainage tile, installed to make soil tillable in Iowa’s Des Moines Lobe, is among the factors being blamed for the high levels of nitrates entering local waterways.
KCRG-TV9 reports a surge in nitrate levels forced the Des Moines Water Works to activate its nitrate removal facility on Dec. 4. High concentrations of nitrates usually occur in the spring and early summer, when rains wash nutrients from farm fields. But this year, from September through November, levels in the two rivers that supply Des Moines’ drinking water have been among the highest ever recorded.
As of Dec. 16, nitrate levels remained above the 10-parts-per-million considered safe in drinking water.