At low tide, the waters of Puget Sound reveal an amazing abundance of oysters, clams, mussels, and more—a bounty unparalleled elsewhere. Gathering shellfish is a time-honored tradition for the public, and today it is an industry that supports thousands of jobs and brings millions of dollars into the region.
Around Puget Sound, there are an estimated 190,000 acres of classified commercial and recreational shellfish beds. However, about 36,000 acres of shellfish beds—approximately 19%—are closed due to pollution, most of which comes from fecal bacteria from humans, livestock, and pets. When fecal bacteria and other contaminants get into the water, they threaten the areas where these prized oysters, clams, and other bivalve shellfish grow.
Acres of harvestable shellfish beds
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. A minimum of 30 of the most recent samples from each marine water station are used to classify each shellfish harvesting area. 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.
A net increase of 10,800 harvestable shellfish acres, including 7,000 acres where harvest had been Prohibited, between 2007 and 2020.
Yes, there is progress toward the 2020 target.
Any shellfish bed whose status is upgraded results in newly harvestable acres that are counted toward the 2020 target. Between 2007 and April 2013, more acres of shellfish beds were upgraded than downgraded across all classifications, resulting in a net increase of 2,888 acres of harvestable shellfish beds. A net 3,879 acres of shellfish beds were upgraded from the Prohibited classification (4,026 acres upgraded minus 147 acres downgraded to Prohibited).
However, these upgrades in growing area classifications from 2007 through April 2013 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.
Since 2007, some shellfish harvest areas were upgraded while others were downgraded. The net result was a net increase of 2,888 acres. A classification downgrade in April 2011 within the Samish Bay shellfish growing area (4,037 acres) dramatically impacted the net acreage gained since 2007.
Of the total harvest area classified in 2013, 154,190 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 April 2013 sanitary conditions improved resulting in net upgrades in classifications totaling 2,888 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 most recent Department of Health prediction indicates that 8,186 acres could potentially be upgraded between 2013 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 April 2013 net acreage increase of 2,888 acres, results in a predicted increase of 11,074 acres by 2020, just above the 10,800 acres target value. However, downgrades are almost certain to occur during the same timeframe, counteracting the projected upgrades and potentially impacting the ability to meet the target value.
Although the Sound-wide trend in improvement is positive, many factors affect the long-term ability to reach the target. Unless there are aggressive actions to improve farm management, wastewater treatment plant outfall locations, and on-site septic system operation and maintenance the 2020 target may not be met.
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. Areas where harvest is not allowed are also distributed across all sub-basins of Puget Sound.
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