The Des Moines Water Works (DMWW) recently issued a notice of intent (NOI) to sue three County Board of Supervisors that oversee several drainage districts reportedly responsible for excessive nitrate pollution being discharged from groundwater in subsurface agricultural drainage systems into the Raccoon and Des Moines Rivers.

Recent sampling efforts by DMWW have indicated nitrate levels in the groundwater discharged from these drainage districts as high as 39.2 milligram per liter (mg/L), well in excess of US EPA’s 10 mg/L maximum contaminant level (MCL) for nitrate.  When needed, DMWW operates a nitrate removal facility that was built in the early 1990s to treat excess nitrate loading in raw water from the Raccoon and Des Moines Rivers that is used to supply drinking water to approximately half a million Iowans.  According to the NOI, DMWW expended close to $900,000 to operate its nitrate removal facility during the spring and summer of 2013.  DMWW also reports that it had to employ its costly denitrification facility just this past December in order to address unusually high nitrate concentrations.  In addition, DMWW has invested a large amount of capital in projects aimed at natural nitrate removal and avoidance.

Faced with climbing nitrate treatment costs, DMWW’s NOI outlines its intention to hold upstream agricultural drainage districts accountable for addressing nitrate pollution, primarily through permitting requirements under the Clean Water Act (CWA) and analogous state law.  Under the CWA, stormwater runoff from farming operations is typically exempted from CWA point source permitting requirements as “agricultural stormwater discharge and return flow from irrigated agriculture.”  33 U.S.C. § 1362(14).  However, DMWW argues that these exemptions do not apply because nitrate pollution from these subsurface drainage districts is conveyed by artificially drained groundwater, not surficial stormwater.  This novel argument is largely untested, although a recent California district court decision did allow plaintiff fishermen to move forward with their CWA claim against administrators of a California subsurface tile drainage system on the grounds that “contaminated groundwater originating in parcels where no farming occurs” cannot be exempt as a discharge composed “entirely of return flows from irrigated agriculture.”

The threatened lawsuit could have potential ramifications for artificial subsurface drainage systems employed extensively throughout the Midwest.  Indeed, DMWW’s NOI takes direct aim at perceived inadequacies with the proposed voluntary nutrient reduction efforts of agricultural sources included in Iowa’s Nutrient Reduction Strategy, which are similar to nutrient strategies being pursued by a number of Mississippi River Basin states.  Given the increased focus on agricultural nutrient pollution, as evidenced by the ongoing litigation regarding the regulation of agricultural pollution under the Chesapeake Bay TMDL (summarized here) and the recent drinking water ban imposed by the City of Toledo as a result of an unprecedented algae bloom, novel efforts to address nutrient pollution such as DMWW’s are likely to persist.