What act established that the EPA must assist in reducing silvicultural water pollution?

The correct option is the Water Pollution Control Act. This act was a foundational piece of legislation in the United States aimed at regulating the discharge of pollutants into the waters of the United States, thereby protecting water quality. It mandated that various federal and state agencies, including the Environmental Protection Agency (EPA), take action to address both point and nonpoint sources of pollution.

Specifically, the Water Pollution Control Act empowers the EPA to develop programs that aim to manage and mitigate pollution from different sources, including silvicultural operations, which can impact waterways through sediment runoff, chemical application, and other practices. This act provides the legal framework for the EPA to assist in reducing pollution from various sectors, including forestry timber production.

Other acts mentioned do address water issues but in different contexts: the Clean Water Act is essentially the updated version of the Water Pollution Control Act focused specifically on water quality standards; the National Environmental Policy Act pertains to the environmental impact assessment process before federal projects proceed; and the Safe Drinking Water Act specifically targets drinking water quality standards rather than silvicultural impacts.