The Ninth Circuit held that Los Angeles County Flood Control District (LACFCD) was responsible for the polluted water that flowed out of the concrete-lined portions of the rivers because LACFCD controlled the concrete channels, regardless of the fact that thousands of other dischargers discharged into the rivers upstream of the concrete channels.  In Los Angeles County Flood Control District v. Natural Resources Defense Council the Supreme Court disagreed with the Ninth Circuit.  It held that a “discharge of pollutants,” which creates liability under the Clean Water Act, does not occur when polluted water flows from an improved portion of a navigable waterway into an unimproved portion of the same waterway.  ICMA joined the State and Local Legal Center’s amicus brief in this case.   The significance of this case is that the Court did not expand the definition of “discharge of pollutants,” a key term in the CWA.  Read more about on the SLLC’s website.