Sanitary Survey

The Shellfish Sanitation Program is conducted in accordance with the guidelines set by the Interstate Shellfish Sanitation Conference contained in the National Shellfish Sanitation Program Guide For The Control Of Molluscan Shellfish Model Ordinance. The NSSP is administered by the U.S. Food and Drug Administration.

Classifications of coastal waters for shellfish harvesting are done by means of a sanitary survey, which includes: a shoreline survey of sources of pollution, a hydrographic and meteorological survey and a bacteriological survey of growing waters. Sanitary surveys are conducted of all potential shellfish growing areas in coastal North Carolina and recommendations are made to the Division of Marine Fisheries of which areas should be closed for shellfish harvesting. These areas are available in map version.

A written sanitary survey report is required every three years from each shellfish growing area. This report summarizes and analyzes the data from the water sampling survey, the pollution source survey and the hydrographic and meteorological surveys. From the analysis of the sanitary survey data, the appropriate classification of the waters of the growing area are determined.

Shoreline Survey

In order to correctly evaluate coastal waters for shellfish harvesting, an evaluation of the pollution sources that may affect the area is required. The shoreline survey is conducted of the shellfish growing area shoreline and watershed to locate pollution sources that could have an effect on area water quality. Every three years, shoreline survey staff walk the shoreline of all coastal shellfish growing areas in North Carolina looking for existing and potential sources of pollution. This shoreline survey is conducted as part of a federally mandated triennial sanitary survey to assess the proper classification of shellfish growing waters. Potential sources of pollution such as marinas, multi-slip docks, agricultural areas, subdivisions, septic tanks, wastewater treatment plants and ditching are all evaluated. These shoreline surveys are coupled with water quality sampling to provide a comprehensive look at the health of a given growing area and to assure proper classification. On a yearly basis, these surveys are updated to include any new pollution sources so that any changes can be accounted for within the management plan.

In 2002, the Shellfish Sanitation Program was awarded one of the largest grants in the 14-year history of the Environmental Protection Agency's Wetlands Program to refine the methodology used to conduct shellfish growing area shoreline surveys. The initial pilot project has been completed; it focused on four shellfish growing areas in Carteret County. The survey methodology uses both GIS and GPS mapping technology to identify and spatially map potential sources of pollution, including stormwater outfalls, marinas, slip docks, agriculture and new subdivisions.

In the 2006 legislative session, the section was enhanced with three new positions to expand the new shoreline methodology coastwide. The new shoreline survey methodology has been redesigned to meet the information needs of many different local, state and federal organizations, while at the same time fulfilling the guidelines required to be met by the NSSP. The new methodology includes extensive GIS mapping of pollution sources, compliance information regarding issued permits and other key pieces of data requested by the various agencies involved.

Bacteriological Survey

Bacteriological surveys are the collection of water samples from all shellfish growing areas. A minimum of six sets of water samples are collected from each sampling station in each growing area on a random schedule to access the overall quality of the waters for classification. Waters are classified as either Approved, Conditionally Approved or Prohibited based on the analysis of the data collected from each sampling station.

Approved shellfishing waters must meet a bacteriological standard over the survey period of a median or geometric mean of not more than 14 MPN/100ml and a 90th percentile not to exceed 43 MPN/100ml.

Hydrographic and Meteorological Survey

A summary of the meteorological conditions that have an effect on a growing area must be made within the sanitary survey report. Rainfall and the resultant runoff can cause fecal coliform counts to increase within shellfish growing waters. Climate and weather can affect the distribution of pollutants or can be the cause of pollutant delivery to a growing area. Prevailing winds can determine the distribution of pollutants in a growing area. Rainfall patterns and intensity can affect water quality through pollutant delivery in runoff or cause flooding which can affect the volume and duration of pollutant delivery. All of these factors must be evaluated as part of the overall sanitary survey and classification of shellfish growing areas.

An evaluation of the hydrographic factors that may affect the distribution of pollutants throughout the area must be made. Examples of hydrographic factors are tidal amplitude and type, water circulation patterns, and the amount of fresh water. These factors, along with water depths and stratification caused by density (salinity and temperature) differences, and wastewater and other waste flow rates are used to determine dilution and time of transport.

Tracer dye studies provide site-specific dilution, dispersion and time of travel information. These are required at each wastewater treatment plant that has a direct discharge into shellfishing waters to determine the proper "closed safety zone" around each outfall pipe.

For more information about the shellfish growing water shoreline surveys,
contact the Shellfish Sanitation Office at (252) 726-6827.