Municipal Guide To Clean Water: Conducting Sanitary Surveys to Improve Coastal Water Quality
What are the sources of fecal contamination?6,17
Potentially harmful microbes arrive at beaches and shorelines from various sources in the watershed. Sources may be point (e.g., straightpipe) or non-point (e.g., stormwater runoff). Point sources of fecal contamination are generally direct conduits of pollution and are consid- ered to impact the beach, even where they discharge to upstream waters. Examples of point or direct sources of contamination include sewer cross-connections to storm drains, wastewater treatment plant outfalls, industrial wastewater outfalls, illegal sewage pipe, combined sewer overflows (CSOs) and overboard discharge units (OBDs).
Non-point source pollution—runoff draining from urban, suburban, and agricultural land—is the leading cause of water quality impairment in the US.1 Rain washes the land surface, transporting pollutants to rivers, streams, and storm drains, and eventually to coastal wa- ters. These dispersed, diffuse sources of bacteria generally are difficult to identify. Contaminated runoff is linked to the duration, intensity, and frequency of rainfall and storm events, as well as watershed characteristics such as land use and topography. Boaters discharging waste at sea also can be considered non-point sources of pollution at beaches and shellfish growing areas.
These sources are described in more detail in Part III of this guide.
LaMarr Cannon, Maine NEMO