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What We've Found

The monitoring data are used to assess marine water quality. Summary analyses show sensitivity to eutrophication (the external addition of nutrients to a system) and relative water quality concern for sites within Puget Sound. These analyses are shown below. The latest edition of the Washington State Marine Water Quality report can be viewed or downloaded for more information.

Areas Indicating or Susceptible to Eutrophication

Presented in the graphic below is a compilation of the Marine Waters Monitoring (MWM) data showing station locations where eutrophication is indicated and areas that are susceptible to eutrophication. This summary graphic compiles five water quality indicators that we measure:

1. Degree of density stratification.
2. High fecal coliform bacteria concentration.
3. High ammonium concentration.
4. Consecutive months of below limit nitrate.
5. Low dissolved oxygen (DO).

This graphic presents the best compilation of known problem areas and areas of susceptibility with respect to eutrophication in marine waters.

Eutrophication can lead to environmental problems such as low DO, noxious algal blooms, and fish kills. Thus, we use low DO as an end-point measurement of where eutrophication may have occurred. On the graphic, the MWM stations in Puget Sound that have low DO are shown by red (<3 mg/L = near-hypoxia) and yellow (<5 mg/L = biological stress) dots.  

To assess susceptibility, we use the additional indicators stated above. Eutrophication-susceptible areas are those that are permanently stratified, that indicate natural nutrient-limitation, and/or that show evidence of anthropogenic contributions (high fecal coliform or ammonium concentrations). The MWM stations in Puget Sound that indicate susceptibility to eutrophication are shown in pink. The graphic is a compilation of WY 1990-1995 data. Not all stations were monitored in all years, so classification was based on the occurrence of a condition in one or more years. Prior to Water Year 1990, data is not comparable due to refinements and changes in analytical and sampling techniques.

Results

• In all, 71 % of the stations monitored (29 out of 41) show either low DO concentrations or susceptibility to eutrophication.

• Of the 41 stations in Puget Sound, 15% show hypoxia (red) and another 20 % have DO at biological stress concentrations at some point throughout the year. Some of these stations have naturally occurring low DO, but it is strongly probable that, especially at all of the stations with red dots, humans are exacerbating the problem by adding nutrients.

• The stations that show susceptibility (36%) are areas where nutrient inputs should be carefully planned for and controlled since additions will result in increased primary production with the potential for low DO concentrations to develop. Most of the susceptibility is in South Puget Sound and Kitsap Peninsula, with implications for human population growth and development in these areas.

• MWM stations in Grays Harbor and Willapa Bay do not show low DO concentrations, but both show susceptibility.

El Nino impact on Puget Sound temperature and salinity (14-Apr-1998)

For the previous moderate El Niño event (1992-91), data from the Department of Ecology's Marine Waters Monitoring program showed that Puget Sound surface seawater temperature and salinity were warmer and saltier, respectively. The influence of warmer and drier local weather during that time likely played a large role in this signal. The data and analysis can be viewed in Newton (1995), available from the Puget Sound Water Quality Action Team's Puget Sound Research Conference '95 Proceedings.

Monitoring data for the 1997-98 El Niño event are still being verified and analyzed. However, early indications are that warmer than average sea surface temperatures were observed during winter (Dec `97-Feb `98). The surface salinity signal is less clear. Salinities were exceptionally fresher throughout 1997 due to streamflows well above normal (~150% of mean, see USGS data). Lately, however, salinities have been approaching average values.

Relative Water Quality Concern

The table and figure below show a gradient of concern for marine water quality issues based on Ecology/PSAMP monitoring data from 1994-2000. The concern level is the summed value of five indicators of environmental status listed in the table. The indicator attributes of most concern to water quality are shown in red in the table for each indicator. These were summed to generate a relative scale shaded from yellow (lower concern) to red (highest concern) for the figure.

 

 

Map of stations and relative water quality concern (see table below)

 

DO indicates when waters have had low (<5 mg/L) or very low (<3 mg/L) oxygen concentrations, which can be harmful to some marine organisms, such as fish.

FCB refers to where fecal coliform bacteria are been detected at moderate (>14 orgs/100 mL once or more), high (chronic >14 or >50 once), or very high levels (chronic and >50 orgs/100 mL), which can often be indicative of sewage or agricultural contamination.

DIN refers to where nitrogen dissolved nutrients are at presumably limiting concentrations for consecutive months (3 mo = moderate; 5 mo = low), indicating areas that would be susceptible to added nutrients from point and non-point sources, resulting in reduced water quality.

NH4 relates the finding of high (>0.14 mg/L) or moderate (0.07 mg/L) concentrations of ammonium, which is sometimes indicative of human sources of organic waste, such as sewage or agricultural runoff.

Stratif stands for the natural amount of density stratification that the location has, which influences how readily pollutants will be mixed out or low oxygen concentrations persist.

P=persistent; S=seasonal; E=episodic; W=weak.

 

Table of Marine Water Quality Throughout Puget Sound

	DO	FCB	DIN	NH4	Stratif	Concern
Budd Inlet	Very Low	High	Low	High	P	Very High
S. Hood Canal	Very Low		Low		P	Very High
Penn Cove	Very Low		Low		P	Very High
Commencement Bay	Low	Very High			P	Very High
Elliott Bay	Low	Very High			P	High
Oakland Bay		Very High	Moderate	Moderate	E	High
Grays Harbor		Very High		Moderate	P-E	High
Upper Willapa Bay		Very High	Low	Moderate	E-W	High
Possession Sound	Low	High	Moderate	High	P	High
Sinclair Inlet	Low	High	Low	Moderate	P	High
Bellingham Bay	Low	Moderate	Low	Moderate	P	High
Drayton Harbor		Moderate	Low		S	High
N. Hood Canal	Low		Low		P	High
Port Orchard		High		Moderate	S	Moderate
Case Inlet	Low	Moderate	Moderate	Moderate	S	Moderate
Carr Inlet	Low		Moderate	Moderate	S	Moderate
Quartermaster Harbor	Low			Moderate	S	Moderate
Totten Inlet			Moderate	Moderate	E	Moderate
Saratoga Passage	Low		Moderate		P	Moderate
Holmes Harbor	Low				P	Low
Skagit	Low				P	Low
Port Susan	Low				P	Low
West Point		Moderate			E	Low
Dungeness	Low				S	Low
Port Gamble	Low				S	Low
Sequim Bay	Low				S	Low
Discovery Bay			Low		S	Low
Willapa Bay			Low			Low
Dyes Inlet			Moderate		S	Low
Eld Inlet			Moderate		S	Low
East Sound				High	S	Low
Burley-Minter				Moderate	E	Low
Port Townsend	Low				W	Low
Strait of Georgia	Low				S	Low