The Clean Water Act becomes law on October 18, 1972. After centuries of reckless treatment of American rivers, streams, lakes and bays, the landmark act institutes strict regulations on pollution and quality controls for the nation’s waters for the first time in its history.

The '60s had been marked by some truly horrific revelations regarding water pollution. A 1968 survey revealed that pollution in the Chesapeake Bay resulted in millions of dollars of lost revenue for fisherman, while a 1969 study found that bacteria levels in the Hudson River to be at 170 times the legal limit. The same year, pollution from local food processing plants killed 26 million fish in one lake in Florida, the largest fish kill on record, and an oil slick resulted in an infamous fire on the Cuyahoga River near Cleveland. When President Richard Nixon established the Environmental Protection Agency in 1970, it was clear that water pollution would be one of its top priorities.

Though Nixon was generally very proactive on environmental issues, he vetoed the Clean Water Act, even after it sailed through both houses of Congress, on the grounds that its price tag was too high. The legislature overruled his veto the following morning, and the bill became law on October 18, 1972. The CWA mandated the protection of any waters in the country with a “significant nexus” to navigable waters. It established a framework for identifying, licensing, and enforcing standards on originators of “point source pollution,” contamination stemming from a single point like a factory or sewage treatment plant. It also contained many other provisions for finding, regulating and cleaning up water pollution, giving most of these responsibilities to the recently-created EPA.

Since the CWA took effect, levels of pollution have greatly decreased, although many environmentalists believe it did not do enough to control non-point source pollution, the kind of contamination that cannot be traced back to a single origin. Though the CWA clearly had a positive impact, a high percentage of American waterways still do not meet the water quality standards it set forth.