As filter feeders, bivalve shellfish are a useful indicator of water quality as they can accumulate biotoxins and pollutants present in the water or sediment. As they are easily affected by surrounding water quality conditions, shellfish must be consistently monitored to ensure safe consumption by humans.
Shellfish growing areas are classified by the Washington State Department of Health (DOH) using guidelines from the National Shellfish Sanitation Program (NSSP). DOH uses five classifications: approved, conditionally approved, restricted, prohibited, and unclassified. Shellfish growing area classifications are determined by an evaluation process that includes shoreline surveys to identify pollution sources and marine water sampling for fecal coliform bacteria. DOH regularly monitors all active growing areas and compiles annual reports including updated classifications. For more information on Snohomish County water quality monitoring, visit the Water Quality in the Stillaguamish River basin page.
See map for shellfish harvesting area classifications in Snohomish County (PDF).
View map (PDF) of shellfish growing area classifications throughout Washington State.
National Shellfish Sanitation Program
The purpose of the NSSP is to promote and improve sanitation of shellfish moving in interstate commerce and uniformity of state shellfish programs. The NSSP guide ensures that shellfish produced in states in compliance with the guidelines are safe and sanitary. The guide includes adoptable standards and administrative practices for sanitary control of shellfish.
Commercial Shellfish Growing Area Status
Growing area status is continuously monitored by DOH. Significant changes in Port Susan and South Skagit Bay status are listed below:
- 1987: DOH closed 18,000 acres of tidelands in South Skagit Bay and Port Susan to commercial shellfish harvest primarily due to fecal bacteria pollution from the Stillaguamish River.
- 1993: The South Skagit Bay commercial shellfish harvest area was re-opened for 2,280 acres.
- 2006: The South Skagit Bay growing area is upgraded from Conditionally Approved to
Approved, but reduced to 1,344 acres.
- 2009: The South Skagit Bay commercial shellfish harvest area was expanded to 2,200 acres.
- 2010: The Port Susan commercial shellfish harvest area was re-opened for 1,800 acres.
- 2014: Commercial shellfish harvest at previously unclassified areas of McKees Beach and Warm Beach were upgraded to approved after a study encouraged by the Stillaguamish Tribe.
Commercial Shellfish Harvest
Eastern Softshell clams are commercially harvested in the South Skagit Bay growing area. This species is highly sought after on the east coast of the United States but has a smaller recreational harvest on the west coast. The graph (PDF) below shows harvest from 2001-2015.