Shellfish Growing Area Surveys

Photo of sewage outfall into open water.  Photo credit - Yves Lamontagne, MWQM Quebec.The major program activity for EC under the Marine Water Quality Monitoring Program is the shellfish growing area (sanitary) survey which has three main components - the identification of pollution sources through a shoreline survey, meteorological and hydrographic studies and bacteriological studies.

Types of surveys

Shoreline sanitary investigations include the evaluation of all actual and potential sources of pollution. Sources of pollution can include:

  • municipal sewage discharged into the receiving water body (or inflowing rivers to the receiving water body)
  • leachate from on-site systems
  • discharges from boats
  • agricultural and wildlife run-off
  • surface runoff from polluted areas
  • industrial wastes

The purpose of hydrographic studies is to:

  • determine the effects of rain, wind, tides and currents in disseminating pollution over the growing areas
  • estimate the water available to dilute effluents to approved standards
  • estimate the time of travel of pollution from the source to the growing waters
  • determine the physical properties of the water, including salinity, temperature and turbidity

Monitoring of indicator bacteria in the growing waters is necessary to determine the extent of fecal contamination, provide quantitative data for the classification of growing waters and delineate closure boundaries. 

Frequency of surveys

Laboratory photo of water testing. Photo credit - Yves Lamontagne, MWQM Quebec.Each harvesting area must undergo a comprehensive survey to determine the sources of point and non-point pollution, the degree of contamination and the extent of area contamination. Classifications are based on the analysis of fifteen sampling runs at every station.  

The CSSP requires a complete re-evaluation of the classification of each shellfish growing area (Approved, Conditionally Approved and Restricted areas which are used for Depuration or for Short-term Container Relaying) at least once every three years. The complexity and extent of a re-evaluation survey will be specific for each area and may require some or all of the elements of a comprehensive survey. A re-evaluation of a shellfish growing area is required within one year if the annual review shows that the sanitary quality of an area is likely to be significantly altered by new or changes in the pollution sources. Remote areas may be evaluated at a lesser frequency. Annual review surveys update the classification of the area and include a minimum of 5 samples at stations in non-remote areas.

While Environment Canada does not undertake chemical testing at the growing area under the CSSP, it will advise its CSSP partners, DFO and CFIA, of its concerns of specific pollution sources as a result of its shoreline investigations. And, as it is made aware of data from other specific investigations, it will also provide that information to its CSSP partners.