Coal ash ponds near the Cape Fear River, in North Carolina. Click image to enlarge. The Clean Water Act, the landmark environmental statue that Congress passed in 1972, does not explicitly regulate the pollution of groundwater. That could change. Lawsuits before federal courts in three states argue that the federal government does have the power to hold polluters accountable — if the groundwater eventually flows into a river, lake, ocean, or stream already under Clean Water Act jurisdiction.