Answer:
A. when a permit has been issued.
Explanation:
The Clean Water Act refers to the primary federal act in the United States administering water pollution. The chief objective of this act is to preserve and rebuild the physical, chemical, and biological honor of the water of the nation.
According to the Clean Water Act, it is legal to release point source of pollution only in case of permission has been issued by the National Pollutant Discharge Elimination System (NPDES) which is introduced by Clean Water Act (CWA).
