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Indicator: Marine Sediment Quality

Data and Data Discussion provided by King County DNRP

Marine Ambient Sediment Quality

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Upstream Indicators
  •   Urbanization and Impervious Surface Changes --- The number of acres of urban land, clear-cut, and regenerating forest have increased in King County since 1986. Acres of grass and deciduous, mixed and coniferous forest have decreased. Acres of rural forests and privately owned working forests have declined in recent years  (view data graph)
  •   Consumer Environmental Index --- Through their purchasing decisions, Washington consumers have increased their total environmental impacts by 24% since 2000. Even on a per capita basis consumption impacts have gone up 17%.   (view data graph)
  •   Organic Farm Trends --- The number of certified organic farms in King County has more than tripled from 7 in 1995 to 23 in 2002, and remained relatively constant since then. The amount of acreage in organic production increased substantially in 2007.   (view data graph)
  •   Air Releases of All Reported Toxic Chemicals --- Overall, there has been a substantial decrease in toxic air emissions since the late 1980s in King County, particularly in the South Region. Since 2000 the total toxic emissions have decreased by about half. However, some communities are at greater risk of toxic exposures.  (view data graph)
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Downstream Indicators
  •   Pollution in Neighborhoods --- It appears that some neighborhoods, particularly those with lower income levels and greater racial diveristy, are more at risk of pollution from Toxic Release Facilities, hazardous waste sites, and other sources.  (view data graph)
  •   Toxins Found in Bodies --- The data we have at this time is a snapshot of the level of some toxins people are carrying around in their bodies. We don’t yet have the research to tell us if these numbers are going up or down or even what the current levels might signify in terms of human health. 
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Related Goals

Sustainability Snapshot:

Contaminated sediments can affect large areas of an ecosystem. When organisms live in or eat in these areas of contamination, not only are they directly harmed but they also accumulate contaminants in their tissues and transfer them throughout the food web. Many of the most of contaminated areas in Puget Sound are in or around urban developments as well as sensitive estuarine areas that are critical to the food supply of many fish and wildlife.

Sustainability Trend:

Marine sediment quality is fairly steady in Puget Sound. Sediment contamination increases and are reduced only over many years.

Data Discussion

The Indicator Defined

Percent of marine sediment sites that met state standards for sediment quality in King County.

Data Interpretation/Evaluation

This indicator is based on Washington State's Sediment Management Standards which identifies and seeks to reduce and ultimately eliminate adverse effects on biological resources and any significant human health risk from surface sediments in marine, low salinity or estuarine and freshwater environments. The Sediment Quality Standard, or "no adverse effects level," is the most protective chemical standard for marine sediments. The Cleanup Screening Level, or the "minor adverse effects level," helps identify areas of potential concern that may be designated cleanup sites.

Based on 2001 sampling data, two ambient sites do not meet sediment quality standards, but do not exceed the cleanup screening levels. Both sites are located within the Duwamish waterway, and there are no specific plans to address them at this time. As such, the ambient target is considered a "non-degradation" target such that conditions should not get worse.

Of the 15 point source-related sites that exceed the Sediment Quality Standard, eight do not require clean up or monitoring. Six of the remaining seven point source sites are associated with combined sewer overflow outfalls, and one is associated with an emergency overflow.

Influencing factors: Many pollutants found in the environment are not detected in water, but are attached to sediment particles. Once in the sediments, these pollutants can directly harm marine organisms or be reintroduced to the food chain through the organisms found in marine sediments.

Data Source and Limitations

The Sediment Quality Standard has been selected as the indicator because it is the more sensitive of the two criteria for environmental protection. Data from 2001 are used because they represent the most recent comprehensive survey of sediment quality in King County. In 2001, sediment sites were divided into two categories. Ambient sites were chosen to reflect general, or ambient, environmental conditions. Point source stations are located near King County wastewater treatment plant outfalls and combined sewer overflow outfalls.

Data from 2001 is still relevant for analysis because sediments (particularly those that are polluted) move slowly and don't change much over five years unless clean up efforts have been taken.

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