On January 8, 2013, the U.S. Supreme Court held that a discharge of polluted water from an improved (concrete lined) portion of a waterway into an unimproved (natural condition) portion of the same waterway does not require an NPDES permit. Los Angeles County Flood Control District v. NRDC. The Supreme Court followed its prior ruling in South Fla. Water Management Dist. v. Miccosukee Tribe, 541 U.S. 95 (2004) wherein it held the transfer of polluted water between two parts of the same water body does not constitute a discharge of pollutants. The United States agreed with this decision via an Amicus Curiae brief.
