Dive summary:

• The L.A. County Flood Control District won over the Natural Resources Defense Council when the nation's highest court ruled that the district did not need a pollution discharge permit if it channels contaminated water out of a waterway, through a manmade channel and back into the same waterway.
• The Supreme Court ruling, which was made last week, was unanimous in saying the Clean Water Act did not apply, which could affect stormwater projects nationwide.
• The ruling overturned a Ninth Circuit Court of Appeals ruling that said the district did have to deal with pollution when it went back into the Los Angeles and San Gabriel rivers whence it had come.

From the article:

The Court’s decision clarifies that the flow of water through a man-made construction (such as a dam, penstock, and/or powerhouse) within the same waterway does not qualify as a discharge of pollutants and does not require an NPDES permit. ...