A more thorough explanation:

The Clean Water Act (CWA) is a law in the United States that aims to prevent and fix water pollution. It is a significant piece of environmental legislation that gives the Environmental Protection Agency (EPA) the power to protect water quality by monitoring standards and controlling discharge from point sources.

The EPA and states work together to regulate water quality standards. States must classify bodies of water by their designated use, such as swimming, fishing, water supply, navigation, or industrial waste disposal. They must then create a plan to ensure the water meets the standards for that use. The EPA must approve these plans, which require pollution limits to ensure the water is of high enough quality for its designated use and that the designated uses will not result in further degradation of waterways.

For example, if a river is designated for fishing, the state must ensure that the water quality is good enough for fish to live in and be safe for people to eat. The state must also make sure that the river's water quality does not get worse over time.

The CWA also requires the regulation of point sources, which are stationary locations that discharge pollution into water. Discharge of a pollutant from a point source into waters of the United States is illegal without a National Pollution Discharge Elimination System (NPDES) Permit. NPDES permits are issued by the EPA or states that obtain EPA approval. These permits include limits on how much pollution can be discharged and require mandatory reporting and monitoring procedures.

For example, a factory that discharges wastewater into a river must obtain an NPDES permit that limits the amount of pollutants it can discharge. The permit also requires the factory to monitor and report its discharges to ensure it is not exceeding the limits.

The CWA applies to the "navigable waters" of the United States, which includes wetlands and areas directly adjacent to navigable waters. However, it does not apply to unconnected ponds or areas that are not directly connected to navigable waters.

For example, a small pond in the middle of a field that is not connected to any other waterway is not covered by the CWA. However, a wetland that is connected to a river is covered by the CWA.

The CWA is an important law that helps protect our water resources and ensure that they are safe for people and wildlife.