Marine Water Quality
As dissolved oxygen decreases, it becomes harder for animals to get the oxygen they need to survive.
Indicator Lead: Christopher Krembs, Washington State Department of Ecology
Data last updated on March 21, 2014
Photo Credit: Duane Fagergren, Puget Sound Partnership

Importance to Puget Sound recovery

Every time we visit the beach, fish, or dig clams in Puget Sound, we rely on good water quality. Marine water quality in much of Puget Sound is poorer than we would like, especially in areas where the circulation of water is restricted.

The marine waters of Puget Sound are affected by many different factors including weather and climate, inflow from rivers and streams, discharges from wastewater treatment plants and industries, off-shore ocean conditions, storm-water runoff, and even ground water.

Excess pollution can force beach closures and shellfish harvesting restrictions, and may cause algae blooms that eventually deplete oxygen levels leading to fish kills.

Is there progress? Indicators and targets

What is the indicator?

There are two indicators for the Marine Water Quality Vital Sign: the Marine Water Condition Index and dissolved oxygen.

Marine Water Condition Index

The Washington State Department of Ecology developed the Marine Water Condition Index to better address the large amount of variability inherent in marine water quality measures, in order to detect subtle and persistent changes over time. The Marine Water Condition Index integrates 12 variables that describe an important aspect of water quality conditions (e.g. temperature, salinity, nutrient balance, algae biomass, dissolved oxygen, etc.).

The goal of the Marine Water Condition Index is to provide a framework that links changes in local water quality and physical conditions to a larger context of oceanic water quality and natural variability. The Marine Water Condition Index can detect subtle changes in water conditions relevant to eutrophication and physical conditions against site and seasonal-specific baseline conditions measured from 1999 to 2008.

The index is reported on a scale of -50 to 50 indicating a complete change from baseline conditions, with zero indicating unchanged conditions relative to the baseline. The index is reported for 12 regions (Figure 1 in Latest data and maps sections).

Dissolved oxygen

Low dissolved oxygen has been observed in a number of locations in Puget Sound and can create significant problems, such as extensive fish kills. Human inputs, especially of nitrogen, are often suspected of creating, or exacerbating, the conditions which lead to low oxygen in Puget Sound. Low oxygen are connected to other problems such as high carbon dioxide in the water and more acidic waters. To reduce the frequency and severity of oxygen and associated problems in Puget Sound, the Leadership Council adopted a target intended to minimize any human contributions to low dissolved oxygen in Puget Sound.

The problem is, dissolved oxygen naturally exhibits a high degree of variability in marine waters, changing almost continuously with time of day, location, season, tidal cycle, depth, the mixing and movement of different water sources, and many other factors. Also, there are several main sources of nitrogen entering Puget Sound, including the ocean (generally the largest overall source), terrestrial sources (some of which are natural, and some of which are human), groundwater, and the atmosphere.

Consequently, determining the precise degree to which human inputs are responsible for a relatively small decline in dissolved oxygen, relative to the normal range of variability, is a complex issue. Addressing the issue requires a combination of good monitoring data, studies on the sources of nitrogen, and sophisticated mathematical models.

What are the targets?
2020 target

The Leadership Council has not adopted a specific target for the Marine Water Condition Index.

The Leadership Council did, however, adopt a 2020 target related to one key component of the index: Keep dissolved oxygen levels from declining more than 0.2 milligrams per liter in any part of Puget Sound as a result of human input.

Interim targets

Link to interim targets for dissolved oxygen(PDF)

Is there progress?

Marine Water Quality Target Bar

Marine Water Condition Index

Marine water quality was slightly lower in Puget Sound in 2012 relative to the 10-year, 1999-2008 baseline. However, looking more closely at water quality region by region, there was quite a bit of variability in 2012. Conditions were much better in some regions relative to the baseline (e.g. Admiralty Reach, South Sound, Elliott Bay). In other regions, conditions got worse (e.g. Bellingham Bay, Georgia Basin and Budd Inlet). Conditions were at an all time low over much of Puget Sound in 2010, and improved somewhat temporarily in 2011. (Figure 1 in Latest data and maps section).

Latest data and maps

Data

Marine Water Condition

Puget Sound Marine water condition index scores, 1999-2012

Marine Water Condition Index scores have generally declined over the past 14 years, illustrated by a shift from green to red colors and an increase in negative scores (Figure 1). These results indicate that conditions overall are shifting in the direction of lower water quality, although recent, more favorable ocean conditions have slowed the apparent decline in particular in Admiralty Reach and Georgia Basin in the last two years. The largest changes, more than 20% decline, were in, Bellingham Bay, followed by a lesser degree in Central Basin, South Hood Canal, Elliott Bay with a decline of 16% or more.

The largest driver of declining marine water quality has been increasing nitrate concentrations. This also affected the balance of nutrients in the system which can affect the marine food web at its base. Over the past 14 years, nitrate levels have increased steadily despite ocean variability. Because nitrate is an important plant nutrient, increasing nitrate loads can fuel algae blooms which, as the algae subsequently die and decay, can drive low dissolved oxygen events.

There are two dominant sources of nitrate in Puget Sound waters: input from ocean waters flowing into Puget Sound and human pollution. Recent evidence suggests that increasing nitrate but no increase in ocean minerals in Puget Sound points to a predominately non-oceanic source of nitrogen. However, as discussed earlier, the overall contribution of human inputs to low dissolved oxygen in Puget Sound remains a topic of active study.

Dissolved Oxygen

Low dissolved oxygen has been observed in a number of locations in Puget Sound and can create significant problems, such as extensive fish kills. Human inputs, especially of nitrogen, are often suspected of creating, or exacerbating, the conditions which lead to low oxygen in Puget Sound. Low oxygen are connected to other problems such as high carbon dioxide in the water and more acidic waters. To reduce the frequency and severity of oxygen and associated problems in Puget Sound, the Leadership Council adopted a target intended to minimize any human contributions to low dissolved oxygen in Puget Sound.

The problem is, dissolved oxygen naturally exhibits a high degree of variability in marine waters, changing almost continuously with time of day, location, season, tidal cycle, depth, the mixing and movement of different water sources, and many other factors. Also, there are several main sources of nitrogen entering Puget Sound, including the ocean (generally the largest overall source), terrestrial sources (some of which are natural, and some of which are human), groundwater, and the atmosphere.

Consequently, determining the precise degree to which human inputs are responsible for a relatively small decline in dissolved oxygen, relative to the normal range of variability, is a complex issue. Addressing the issue requires a combination of good monitoring data, studies on the sources of nitrogen, and sophisticated mathematical models.

Maps

no map

What you can do

  1. Try to avoid using fertilizers. If fertilizer must be used, choose organic or time-released fertilizers with low levels of phosphorus and nitrogen, and follow the directions on the label.
  2. Instead of fertilizer, use compost to augment your soil and fertilize your plants. Also, compost vegetation and other yard waste; do not throw it over the bank into a waterway or shoreline. See Washington Department of Ecology's composting site for more information.
  3. Plant and maintain native vegetation around your property. Leave a buffer of native vegetation to uptake nutrients and fertilizers before it reaches the lakes, streams of Puget Sound. For more information on native plants, visit the Dept. of Ecology's website or the Washington Native Plant Society.
  4. Use Low Impact Development (LID) techniques to manage stormwater runoff such as natural landscaping, rain gardens, rain barrels, green roofs and permeable paving where appropriate.
  5. Volunteer in your area to work with a group helping to reduce marine water pollution.
  6. Inspect and maintain your on-site sewage system - see Septic System Care at Puget Sound Starts Here.

What our partners are doing

View Near Term Actions helping to advance this Vital Sign

Links for more information

Washington Department of Ecology: Marine Water Quality Monitoring Program

Washington Department of Ecology: Marine Water Quality Monitoring – YouTube video

Hood Canal Dissolved Oxygen Program

Northwest Association of Networked Ocean Observing Systems

"Eyes over Puget Sound"