On Tuesday, December 4, the U.S. Supreme Court is scheduled to hear oral arguments in a case of utmost importance to local water management agencies.  At issue is a July 2011 opinion by the U.S. Court of Appeals for the 9th Circuit that potentially subjects these entities to a new regime of National Pollutant Discharge Elimination System (NPDES) permitting.  The 9th Circuit’s opinion marked a defeat for the Los Angeles County Flood Control District, which was defending itself against a claim by environmental groups that the county was obligated to treat municipal stormwater runoff that entered the county’s municipal separate storm sewer systems (MSs4) and eventually polluted navigable rivers in Southern California.

Four rivers        

In Natural Resources Defense Council v. the County of Los Angeles (NRDC v. LA County), the plaintiffs argued that between 2002 and 2008, polluted water conveyed by the county’s MS4s caused hundreds of water quality exceedances in four rivers–the Santa Clara River, the Los Angeles River, the San Gabriel River, and Malibu Creek.  Detected pollutants included aluminum, copper, cyanide, fecal coliform bacteria, and zinc.  The NRDC and its co-plaintiff, Santa Monica Baykeeper, contended that the county’s NPDES permit makes it responsible for controlling all pollutants that are conveyed into the rivers via its MS4, which comprises 2,800 miles of storm drains and 500 miles of open channels. 

While admitting that it conveys pollutants via the MS4, the county contended that its infrastructure alone does not generate or discharge pollutants. According to the defendants, the MS4 conveys the collective discharges of the numerous “up-sewer” municipalities.  A district court agreed and dismissed the complaint because the plaintiffs were attempting to establish liability without presenting evidence as to precisely who was responsible for the polluted discharges–that is, which of 84 municipalities in the LA County water district were responsible for discharging pollution into the county’s MS4s.

County bears responsibility

But the 9th Circuit saw merit in the plaintiffs’ contention that it is irrelevant which of the thousands of storm drains were the source of polluted stormwater since, as holders of the permit, the defendants bear responsibility for detected exceedances.  The 9th Circuit was somewhat disturbed that the plaintiffs did not present evidence for certain claims, assuming that it was “obvious to anyone how stormwater makes its way from a parking lot in Pasadena into the MS4, through a mass-emissions station, and then to a Watershed River.”  Accordingly, the court elected not to rule on the county’s responsibility for pollutant exceedances in two of the four rivers named in the complaint.

On the other hand, the 9th Circuit noted that the county has ignored its role as controllers of the MS4 and the stormwater it conveys by demanding that the plaintiffs engage in the “Sisyphean task of testing particular storm drains in the County for the source of each pollutant.”  The court also stated that the Clean Water Act (CWA) does not distinguish between those who add pollutants to regulated waters and those who convey what is added.  The 9th Circuit concluded that it is beyond dispute that the county was discharging pollutants from the MS4 to the Los Angeles River and San Gabriel River in violation of its permit.

Miccosukee defense

In its brief to the Supreme Court, the defendants elected to base its defense on a previous Supreme Court ruling (South Florida Water Management District v. Miccosukee Tribe of Indians) in which the justices held that the flow of water from one portion of a river through an engineered improvement and to a downstream portion of the same river does not constitute a regulated discharge of pollutants under the CWA.  The environmental groups regard the Miccosukee defense being employed by the county as irrelevant to liability because the county “does not simply transfer water within a single river.”

In an amici brief, five of the nation’s major organizations representing municipal water districts stated that a ruling against the defendants would be “devastating” to water suppliers and local governmental water managers who would be subjected to NPDES permitting for the first time. 

The Supreme Court is expected to rule in the case this summer.

Click here to read the 9th Circuit’s opinion in NRDC v. LA County.