Unfortunately, even with the improvement of treatment systems, in the 1960s,
water pollution of American rivers was six times greater than in 1900 and
contained acid mine drainage, viruses, pesticides and industrial wastes. Water
pollution became a big issue in the late 1960’s when thousands of dead fish were
being found washed up on shores and some lakes even caught on fire. Pollution
was readily observable by the public and many lakes were closed to swimming.
The release of pollutants into rivers and lakes was a growing concern. Incidents
such as the Cuyahoga River catching fire in 1969 drew attention to water pollution
issues. Articles discussed the contamination of water sources and the impact on
ecosystems.
https://www.fedcenter.gov/Bookmarks/index.cfm?id=2431
