Skip to main content
King County logo

Marine Environment

Trends

2017 Rating Red
2016 Rating Red Indicator Key

About this indicator: King County's Marine Water Quality includes information about the conditions of marine waters.

Status: While, in general, the quality of open waters in Puget Sound is fair, marine water quality conditions in certain areas of King County show evidence of degradation. Waters that are in protected areas without much current are of concern. Water quality conditions have been steady for at least the last eight years.

Influencing factors: Stormwater carrying nutrients from septic systems, chemicals from motor vehicles and nitrogen from fertilizers degrade marine water quality and reduce oxygen levels for the animals that live and depend on Puget Sound habitats.

What you can do:

  • Properly dispose of harmful chemicals, including unused pharmaceuticals and latex paints.
  • Maintain, repair, or replace failing private septic systems.
  • Minimize the use of fertilizers and pesticides by practicing natural yard care.
  • Wash your car on the grass or gravel instead of on the street or driveway, or take it to a car wash.
  • Properly dispose of pet waste

More information about King County's marine waters is available by continuing below for these measures:

 


 

Marine Water Quality Index

Graph showing Percent marine offshore monitoring sites at moderate or high water quality concern levels
Map showing Marine Eutrophication
Marine water quality index
2017 Findings
Download the PDF version.

About this indicator: King County conducts semi-monthly (monthly in January and December) water quality monitoring at 14 offshore locations in Puget Sound, which includes 8 stations located at wastewater treatment plant and CSO outfall pipes. Offshore marine waters in King County are monitored for temperature, salinity, density, dissolved oxygen (DO), light transmittance, nutrients, and chlorophyll. A biological sampling component (both phytoplankton and zooplankton community structure) was added to the marine sampling program in 2014. These variables can be used to assess eutrophication, (the process by which dissolved oxygen concentrations are depressed due to algae growth primarily caused by nutrients), sewage waste (ammonia), food availability to secondary producers (chlorophyll), and marine water habitat quality (dissolved oxygen, temperature, salinity).

Status: 2017 findings indicate that the water quality at 11 of the 14 stations is at a low level of concern. The number of stations at a low level of concern was 12 in 2016, 11 in 2015, and 8 in 2014. The station in Elliott Bay was at a moderate level of concern in 2017 due to two consecutive months of low DO values ( <5.0 mg/L) and strong and intermittent density stratification. This site was also at a high or moderate level of concern several times between 2009 and 2016 due to low DO values and strong stratification. Rainfall in 2017 was well above average in February and March and also above normal for several other months during the year, including October and November. The rainfall pattern caused a large amount of freshwater discharge to Elliott Bay via the Duwamish River, resulting in strong density stratification in Elliott Bay for half the year.

Both the inner and outer Quartermaster Harbor stations were at a high level of concern in 2017. The station in outer Quartermaster Harbor was at a low level of concern in 2016 but at a moderate or high level of concern between 2009 and 2015, primarily due to low DO values. For 2017, the outer station had consecutive months of <5 mg/L DO and five consecutive months of very low surface dissolved inorganic nitrogen (DIN),The inner station was at a moderate level of concern in 2016 and generally at a high level of concern between 2009 and 2015, primarily due to very low DO. The inner, shallower station, was at a high level of concern in 2017 due to very DO values <3 mg/L in the fall as well as six consecutive months of very low surface DIN. The two Quartermaster Harbor sites are currently monitored with in situ water quality monitoring equipment due to the high level of concern for these waters, particularly in regards to low DO values observed during the late summer and early fall months.

The percentage of stations of Moderate or High Concern is 21.4%, which is similar to 2015 but higher than 2016. The Quartermaster Harbor stations have consistently received a moderate or high concern ranking for the past several years.

Influencing factors: Nutrients and vertical water density patterns can be indicators of an area's potential sensitivity to developing low dissolved oxygen conditions. Low oxygen conditions are harmful to fish and other aquatic life and may occur as a result of the natural flow of low oxygenated Pacific Ocean water into the deep main basin of Puget Sound, in addition to processes such as eutrophication. Persistently low nitrate concentrations in surface water can indicate a potential sensitivity to nutrient-rich input such as stormwater runoff, industrial waste discharges, septic systems, and flow from rivers. Ammonia can be found at elevated concentrations as a byproduct of sewage, agricultural practices, and fertilizer use in urban areas. Elevated ammonia values are also seen following large phytoplankton (microscopic marine algae) blooms as part of the degradation process.

Existing DNRP response: DNRP will continue to operate its wastewater treatment plants and conveyance system effectively to maintain low levels of nutrients discharged into marine waters. The new Brightwater Treatment System uses state of the art technology to reduce nutrients and other pollutants. King County, along with other monitoring partners, is currently involved in a four-year study to assess the role of nitrogen, if any, on dissolved oxygen levels in Quartermaster Harbor. Nutrient levels are also addressed by the agency through stormwater control management practices. Additionally, DNRP will continue to play an active role in the Puget Sound Partnership toward improving water quality throughout the entire Puget Sound.

Priority new actions: Stratification intensity and its persistence is beyond King County's influence, but should be monitored as it is an important indicator of areas sensitive to possible water quality problems.

Data source: The data source for this indicator comes from the King County DNRP/WLR Division's Marine and Sediment Assessment Group.

Collection frequency: The King County DNRP/WLR Division's Marine and Sediment Assessment Group conducts monthly sampling at 14 offshore locations. Three in situ monitoring systems are deployed off piers and collect water quality data at 15-minute intervals.

Methods for analysis: Four indicators are integrated into a modified version of the water quality index developed by the Washington State Department of Ecology to assess overall water quality. The determination of water quality concern is based upon dissolved oxygen, dissolved inorganic nitrogen, ammonia, and stratification strength and persistence. To rank these attributes for the index, two thresholds for each of the indicators has been identified as follows: 1) occurrence of low DO concentrations (<5 mg/L for 2 consecutive months, < 3 mg/L for one month); 2) consecutive months with very low surface DIN concentrations (3 months, 5 months); and 3) elevated ammonia concentrations (>0.8 mg/L, >1.6 mg/L); and 4) presence of strong density stratification (Strong-Intermittent, Strong-Persistent). If numerical values are attached to the two threshold indicator levels, then rankings of relative water quality concern can be derived. A value of "1" is assigned to the first threshold in all categories, and a value of "5" is assigned to the second threshold. A water quality level of concern based upon total points is then assigned to each station. Three water quality levels designations exist and are defined as "Lower Concern" (zero to one point), "Moderate Concern" (two to four points), and "High Concern" (five or more points).

Data Reference: King County, Water and Land Resources Division, Science, Monitoring and Data Management Section

King County DNRP/WLRD Routine and Offshore Water Column Monitoring Program



Fecal Bacteria in Offshore Marine Waters (ambient and outfall)

About this indicator: The presence of fecal bacteria in water bodies indicates contamination with the fecal material of humans, birds, or other warm-blooded animals. Although these bacteria are usually not harmful themselves, they can occur in conjunction with other disease-causing pathogens, and their presence at high levels indicates an increased possibility that people might get sick if they come into contact with the water.

Washington State has a marine surface water quality bacteria standard based upon fecal coliforms. This standard was derived for the protection of human health and addresses water quality requirements for both primary contact recreational uses (e.g., swimming and SCUBA diving) as well as the consumption of shellfish. This fecal coliform standard is a geometric mean of 14 colony forming units /100ml, calculated over a 12-month sampling period.

King County conducted monthly or semi-monthly water quality monitoring in 2017 at 14 offshore locations in Puget Sound. From March until early June of 2017 samples at four of the routine stations were sampled weekly in response to the flooding and restoration of the West Point Treatment Plant. Routinely sampled offshore monitoring locations are divided into two categories, ambient and outfall stations. Ambient stations are chosen to reflect general, or ambient, environmental conditions, while outfall stations are located at King County wastewater treatment plant outfalls and county-operated combined sewer overflow outfalls. Monitoring occurred at eight outfall stations and six ambient stations in 2017. Ambient stations were located in the Central Basin of Puget Sound as well as Elliott Bay and Quartermaster Harbor.

The status of this indicator is based upon the geometric mean of the fecal coliform bacteria counts over the 12-month period of calendar year 2017 in samples collected from the 14 monitoring stations at a depth of one meter below the surface. While bacteria samples may be taken from multiple depths, the one meter (near surface) samples are used for this indicator because human contact is mostly limited to surface waters where bacteria concentrations tend to be the highest.

Status: All ambient and outfall stations met the fecal coliform bacteria geometric mean standard in 2017. Fecal coliform bacteria counts do not appear to be an ongoing concern in marine offshore surface waters within King County.

Influencing factors: Fecal coliform bacteria can enter Puget Sound from domestic animals, wildlife, storm water runoff, wastewater discharges, and failing septic systems. Non-point source pollution (e.g., storm water runoff and agriculture) are often a major cause of marine water bacterial contamination.

Existing DNRP response: DNRP will continue to manage its wastewater treatment plants and conveyance system effectively. The county is working with the Puget Sound Partnership effort toward protecting and restoring the health of marine waters.

Priority new actions: No major changes to the offshore marine water quality monitoring program are planned for 2018. Sites will continue to be monitored twice a month from February through November and once a month in December and January.

Map showing fecal bacteria at ambient monitoring sites
Fecal bacteria at ambient monitoring sites
2017 Findings
Download the PDF version.
Map showing fecal bacteria at wastewater outfall sites
Fecal bacteria at wastewater outfall sites
2017 Findings
Download the PDF version.

 

Data source: The data source for this indicator comes from the King County DNRP/WLR Division's Marine and Sediment Assessment Group.

Collection frequency: The King County DNRP/WLR Division's Marine and Sediment Assessment Group conducted semi-monthly sampling from February thru November and monthly sampling from December to January at 14 offshore locations. Offshore monitoring stations are divided into two categories: ambient stations are chosen to reflect general, or ambient, environmental conditions; outfall sites are located at King County wastewater treatment plant outfalls and county-operated combined sewer overflow outfalls. The term "offshore" in this indicator refers to sites that are not classified as beach sites.

Methods for analysis: Fecal coliform results are compared to the current marine water fecal coliform standard, a geometric mean of 14 colony forming units/100 ml. Samples either meet or do not meet the marine water fecal coliform standard. Note that previously, bacteria data were compared to standards on a monthly basis (e.g., rolling geomean) and any failures during that year were indicated. 2017 data were compared to standards as a discrete 12-month period to better illustrate the status of water quality during the year.

Data Reference: King County, Water and Land Resources Division, Science and Technical Support Section, Marine and Sediment Assessment Group

King County DNRP/WLRD Routine and Offshore Water Column Monitoring Program