Pollution in this context is any material that is entering the river and increasing bacteria counts. The Department of Marine Resources (DMR) measures water quality throughout the year, taking samples from specific stations, and adjusting shellfish closures types from those samples.
Types of Pollution
Non-point Source
Non-point source pollution occurs as a result of runoff. Water runs through multiple spaces and picks up bacteria, chemicals, and other harmful substances. This water then ends up in rivers and estuaries, impacting clam flats. This type of pollution is particularly difficult to manage because it comes from so many different places. The amount of harmful substances may be relatively low compared to point sources.
Point Source
Point source pollution is any pollution that has an easily identifiable source. This pollution is usually easier to fix because you are able to monitor the source. Point source pollution can include drain pipes, ditches, sewer outfalls, factories, power plants, and others.
Photos depicting common types of point source dischargers to surface waters in the United States. These facilities are required to obtain discharge permits from the National Pollutant Discharge Elimination System (NPDES).
The Mudflat 