Water Quality

Eutrophication

About this indicator: King County conducts monthly water quality monitoring at 12 offshore locations in Puget Sound. Offshore marine waters in King County are monitored for temperature, salinity, density, dissolved oxygen, nutrients, chlorophyll and fecal coliform bacteria. 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 (fecal coliform, ammonia), food availability to secondary producers (chlorophyll), and marine water habitat quality (temperature, salinity).

Status: 2006 findings indicate that the water quality at all of the ambient and outfall offshore stations sampled is at a level of lower concern.

The percentage of stations of Moderate or High Concern reached a maximum of 22 percent in 2000 and has declined to zero percent for the past three consecutive years.

Influencing factors: 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.

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. Nutrient levels are also addressed by the agency through storm water control management practices. Additionally, DNRP will continue to play an active role in the recently formed 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.

Eutrophication Potential 2006 Findings Click to download the PDF version.

Fecal Bacteria

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, they often occur 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.

This standard addresses water quality requirements for protecting swimming, SCUBA diving and other recreational uses. For marine surface waters, the current fecal coliform standard is a geometric mean of 14 colony forming units /100ml.

King County conducts monthly water quality monitoring at 13 offshore locations in Puget Sound. Offshore monitoring sites are divided into two categories: ambient sites are chosen to reflect general, or ambient, environmental conditions, while outfall sites are located at King County wastewater treatment plant outfalls and county-operated combined sewer overflow outfalls.

Status: Fecal bacteria are not a concern in parts of the Puget Sound that surround King County. All ambient and outfall sites met the fecal coliform bacteria geometric mean standard in 2006.

Influencing factors: Non-point source pollution is the major cause of marine water contamination. Fecal coliform can enter Puget Sound from domestic animals, wildlife, storm water runoff, wastewater discharges and failing septic systems.

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: Monitoring stations have been added in 2007 in Salmon Bay and Fauntleroy Cove.

Fecal bacteria at ambient monitoring sites
2006 Findings
Click to download the PDF version.

Fecal bacteria at wastewater outfall sites
2006 findings
Click to download the PDF version.