Clean Water Act (Cwa)
The law that defines the United States Environmental Protection Agency's (EPA's) responsibility to protect and improve the nation's water quality. Among other things, the EPA regulates the discharge of pollutants and sets quality standards for surface waters. The Clean Water Act began as the Federal Water Pollution Control Act of 1948, which was the first major federal law to address water pollution. That law was significantly amended in 1972 and then again in 1977, when it became commonly known as the Clean Water Act.