We’ve made some changes to EPA.gov. If the information you are looking for is not here, you may be able to find it on the EPA Web Archive or the January 19, 2017 Web Snapshot.

Polluted Runoff: Nonpoint Source Pollution

Nonpoint Source Monitoring

Our nation's waters are monitored by state, federal, and local agencies,  tribes, universities and volunteers. Water quality data are used to characterize waters, identify trends over time, identify emerging problems, determine whether pollution control programs are working, help direct pollution control efforts to where they are most needed and respond to emergencies such as floods and spills.

Nonpoint sources of water pollution are both diffuse in nature and difficult to define. Water quality monitoring for nonpoint sources of pollution includes the important element of relating the physical, chemical and biological characteristics of receiving waters to land use characteristics. Without current information, water quality and the effects of land-based activities on water quality cannot be assessed, effective management and remediation programs cannot be implemented, and program success cannot be evaluated.