The lecture reviews water law in the United States, and highlights challenges inherent in regulating water quality. Aging water infrastructure, pesticide and herbicide application, and surface water runoff all pose challenges in maintaining a clean drinking water supply. The lecture covers pesticide management through the Safe Drinking Water Act (SDWA). The management of pesticides and herbicides in drinking water has been heavily influenced by the economic concerns of pesticide and herbicide users as well as the municipal water agencies charged with testing water regularly for regulated chemicals. The lecture concludes with the regulation history of atrazine, a commonly used herbicide that research has shown to be hormonally active.