The Clean Water Act of 1977 passes the responsibility of approving water quality to the federal government. It also makes it illegal to release any pollutant into navigable waters, unless a permit is obtained.
This Act affects practically everyone in the United States. Because of the severity of the issue, the federal government decides to take matters into its own hands.
The Clean Waters Act of 1977, essentially, takes away power from the state governments. No longer do they have a say in how water standards should be regulated.