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Watershed Management Bureau
Shellfish Program
Monitoring Programs: Pollution Sources
Sanitary Surveys: Decisions on whether or not a particular growing area is safe for harvesting are made by conducting sanitary surveys of the area. There are three basic components to a sanitary survey:
Shoreline Survey of Pollution Sources: this is a lot-by-lot inspection of all properties which may affect the sanitary quality of a growing area. Information such as land use, sewage disposal facilities, and potential pollution sources is documented for each lot. Multiple water samples from suspected pollution sources are collected to confirm the presence of high bacterial levels and the need for remedial action. Other techniques (e.g., dye testing sewage disposal systems) may be employed to document the effects of particular pollution sources.
Ambient Water Quality Monitoring: water samples in the vicinity of the growing areas, and in the vicinity of pollution sources, are collected on a regular basis to document water quality and the effects of pollution sources on the growing area. Statistical tests of the results help determine the nature of bacterial pollution (chronic or intermittent), and the degree to which harvesting should be restricted in order to protect
public health.
Hydrographic, Meteorologic, and Other Studies: a variety of studies may be initiated to better understand how identified pollution sources affect the water quality of a growing area. Examples of such studies include dilution/dispersion studies of wastewater treatment plant effluent, rainfall impact studies, documentation of water column stratification and current patterns, and others.
Once a sanitary survey is completed, the area can be properly classified for harvesting. For each growing area, a full sanitary survey is done every 12 years. Classifications are kept current through annual reviews of water quality data and other information, as well as by a formal re-evaluation of the sanitary survey every three years.
DES intends to complete sanitary surveys on all tidal waters by 2005.
Updated: January 30, 2003
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