Department of Health classifies 91 different shellfish growing areas in Puget Sound, covering roughly 190,000 acres. Sites are classified as “approved,” “conditionally approved,” “restricted,” or “prohibited” (Table 1). Upgrades in classification mean that water quality has improved, allowing for fewer restrictions on shellfish harvest. Downgrades mean there are either more restrictions on when shellfish may be harvested or no harvest is allowed at any time. Downgrades are generally caused by fecal bacteria or other pollutants in the water that make the shellfish unsafe to eat.

The shellfish harvest area classification process is defined in federal rules and adopted in state regulations. The Department of Health implements the rules at the state level. The purpose of the Department of Health program is to assure that harvested shellfish are safe to consume. This also includes making certain that pollution sources are continually assessed and marine water quality monitored around every classified harvest area. The data collected for the classification process not only represent the conditions that dictate shellfish harvest, but their trends can also indicate a healthier Puget Sound.

Department of Health samples more than 1,200 marine water stations between six and 12 times each year for fecal coliform bacteria, salinity, and temperature. Between 2.5 to five years of bacteria sampling data are used in the classification of each marine water station. In addition, shoreline pollution sources, including wastewater treatment plants, individual on-site sewage systems, marinas, farms, and any other activity with the potential to impact the shellfish area, are evaluated periodically and results are integrated in the classification process.

Shellfish beds are considered harvestable when their status is upgraded. Between 2007 and 2011, more acres of shellfish beds were upgraded than downgraded across all classifications, resulting in a net increase of 1,384 acres of harvestable shellfish beds. A net 3,290 acres of shellfish beds were upgraded from the Prohibited classification (3,437 acres upgraded minus 147 acres downgraded to Prohibited).

However, these upgrades in growing area classifications from 2007 through 2011 were dramatically offset by the recent downgrade of the Samish Bay shellfish growing area (4,037 acres), impacting the overall net acreage gained since 2007 and slowing progress toward the 2020 goal.

Of the total harvest area classified in 2011, 152,465 acres or 81% was approved or conditionally approved for harvest (see Table 1 in Is there Progress? section). Thus, shellfish harvest is possible in most of the areas under Department of Health jurisdiction, and these areas are distributed across all sub-basins of Puget Sound (Figure 2).

In contrast, more than 35,000 acres (19%) of shellfish harvest areas were classified as Prohibited due to the proximity of pollution sources or poor water quality (see Table under Is there Progress?). More than 60% of this acreage is prohibited because of a nearby wastewater treatment plant outfall, 29% because of nonpoint pollution sources, 8% because of marinas, and 2% because of other factors that could impact public health.

From 2007 through 2011 improved sanitary conditions resulted in net upgrades in classifications totaling 1,384 acres (Figure 1). A classification downgrade in April 2011 within the Samish Bay shellfish growing area (4,037 acres) dramatically impacted the net acreage gained since 2007.

The Department of Health predicted that 8,738 acres could potentially be upgraded between 2012 and 2020. This analysis incorporates information about the known or suspected causes of harvest restrictions and an area-by-area evaluation of the current activities and water quality trends. These projections, coupled with the current 2007 through 2011 net acreage increase of 1,384 acres, results in a predicted increase of 10,122 acres by 2020, just short of the 10,800 acres target value. However, downgrades are almost certain to occur during the same timeframe, thereby counteracting the upgrades and further widening the gap to the target value.

Although the Sound-wide trend in improvement is positive, many factors affect the long-term ability to reach the target. Intensive efforts to restore growing areas, such as in the Samish harvest area, are counter-balanced by shoreline development and polluted stormwater runoff, on-site septic systems, and farms near existing open areas. Unless there are aggressive actions to improve wastewater treatment plant outfall locations, on-site septic system operation and maintenance, and agricultural best management practices, the 2020 target will likely not be met.