Final answer:
The Clean Water Act of 1972 significantly improved U.S. water quality by setting pollution standards and regulating point sources.
Explanation:
The Clean Water Act (CWA) of 1972 has had the greatest impact on water quality in the United States. This regulation made it illegal to dump pollution into surface water without formal permission, setting pollution standards for point sources like industries and sewage treatment plants. The CWA led to significant improvement in U.S. water quality, making water swimmable and fishable.
Learn more about Clean Water Act here:
https://brainly.com/question/40365152
