In 1970, a series of public policies were created to help reduce the effects of air and water pollution on the environment. One policy was the Clean Water Act.

The Clean Water Act (CWA) establishes the basic structure for regulating discharges of pollutants into the waters of the United States and regulating quality standards for surface waters. . .

Under the CWA, the Environmental Protection Agency (EPA) has implemented pollution control programs such as setting wastewater standards for industry. We have also set water quality standards for all contaminants in surface waters.

The CWA made it unlawful to discharge any pollutant from a point source into navigable waters, unless a permit was obtained. . . . Point sources are discrete conveyances such as pipes or man-made ditches.

– “Summary of the Clean Water Act,” US Environmental Protection Agency (EPA)

According to this passage, which scenario would be in violation of the CWA?

An oil refinery directly channels chemical wastewater into surrounding man-made ditches.
Builders construct a landfill that uses liners to reduce wastewater from seeping into the ground.
A water quality expert at a lake records the level of a toxic chemical below current standards.
A paper mill factory gets permission to release an approved amount of discharge into a stream.