This week the U.S. Supreme Court agreed to hear a Clean Water Act (CWA) case that began in Maui and involves a question never definitively resolved about the scope of the CWA; do federal CWA regulatory controls extend to pollutants that move through groundwater before reaching a federal Waters of the U.S. (WOTUS)? While this case does not specifically involve agriculture, the decision will have critical implications for how the CWA deals with nutrients and pesticides that are in tile drainage water that enters jurisdictional ditches and tributaries.

The case revolves around Maui’s practice of injecting treated municipal wastewater into deep wells.  That treated wastewater has been shown to seep through groundwater and then into the Pacific.

Environmentalists argued before the 9th Circuit Court of Appeals that the groundwater is a “conduit” under the CWA through which discharges can be regulated.  Maui opposed this position, but the Court sided with the environmentalists.  Different federal circuit courts have reached the exact opposite conclusion and such “circuit splits” are often the reason why these cases end up at the Supreme Court.

U.S. EPA under the Obama Administration filed a brief with the 9^th Circuit supporting the environmentalists' position.  The Trump EPA is expected to oppose the 9^th Circuit decision before the Supreme Court, but doing so will require careful legal reasoning.

Some observers believe this is the most significant CWA case to come along in many years, perhaps even more important than the challenges to WOTUS.  This could prove to be important to agriculture as well.  If the CWA regulates the movement of pollutants that reach surface water through groundwater, the next arguments will be that the CWA applies to pollutants that get to WOTUS by almost any means, and after any length of time.

Agriculture is expected to file substantial briefs with the Supreme Court opposing the legal reasoning in the 9^th Circuit’s decision, as will most every other U.S. business sector.  UEP will be monitoring these developments and will keep its members informed.