The 1972 Clean Water Act expanded federal protections for the nation’s waterways, allowing the government to regulate what corporations discharge into them, including pollutants. 

That landmark law turns 50 today, just as the U.S. Supreme Court weighs shrinking its reach. 

The years just before the Clean Water Act passed brought some pretty memorable images of polluted waterways. 

“Of pollutants floating through water bodies, rivers on fire,” said Catherine L. Kling, who studies the social costs of water pollution at Cornell. “So the Clean Water Act was a realization that the country did not want to live that way any longer.”

Kling said the law has been pretty effective at improving water quality, which comes with a host of economic benefits, like boosting property values and recreation economies. 

Right now, the Supreme Court is considering the scope of the Clean Water Act.

“What’s at stake is whether we’re going to get a legal interpretation that reflects the science of water, the idea that water is connected,” said Oday Salim with the University of Michigan School of Law. 

Or whether the justices will exclude certain kinds of wetlands and streams from federal protections.