National causes of water impairment

Table: Center for American Progress Source: Source: S.A. Dressing and others, “Monitoring and Evaluating Nonpoint Source Watershed Projects” (Washington: U.S. Environmental Protection Agency, 2016), available at https://www.epa.gov/sites/production/files/2016-06/documents/nps_monitoring_guide_may_2016-combined_plain.pdf.