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Salish Sea

Freshwater Quality


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Of the seventeen rivers we assessed, none showed statistically significant declining trends over the ten year period from 2000 to 2010. Though twelve of the rivers either regularly or occasionally exceeded water quality guidelines, improving trends were observed in three of the rivers (Samish, Nisqually, and Deschutes).

Clean water from streams and rivers that flow into the Salish Sea is essential for maintaining a healthy ecosystem. Excess nutrients, warmer temperatures, and other factors can create water quality problems in lakes and streams that impact the entire ecosystem.

A Freshwater Quality Index (WQI) is tool developed by scientists to help evaluate the quality of water in these streams and rivers. It summarizes large amounts of water quality data into a single "score" from 1 to 100. Higher scores reflect cleaner water.

  • Learn more about Freshwater Quality Indexes

    A Freshwater Quality Index is based on established water quality guidelines and criteria for certain physical and chemical properties of water (e.g., sediments, nutrients, temperature, dissolved oxygen).

    In this report, we used two Water Quality Indexes to evaluate freshwater ecosystems that flow into the Salish Sea. Streams in the Georgia Basin were evaluated by Environment Canada using the Canadian Council of Ministers of the Environment Water Quality Index (CCME WQI). In Puget Sound, we used the Washington Department of Ecology's Water Quality Index.

    Water quality index scores are placed into ranges that help define the quality of the water. These are the ranges we established for this report:

    • WQI scores from 80-100 indicate high water quality, meaning that water quality rarely exceeds guidelines, and if so, only by a narrow margin.
    • WQI scores from 70-79 indicates fair or marginal water quality that sometimes exceeds guidelines, possibly by a wide margin.
    • WQI scores below 69 indicate poor water quality that often exceeds guidelines by a wide margin.

    Note that these ranges may differ from the ranges established for either of the individual water quality indexes referenced. They have been combined here for easier comparison.

What's happening?

The average Freshwater Quality Index scores for 17 major rivers in the Salish Sea watershed from 2000 to 2010 show that:

  • Five rivers have good to excellent water quality (80-100).
  • Seven rivers have marginal to fair water quality (70-80).
  • Five rivers have poor water quality (below 69).
Chart showing average Water Quality Index Scores for 17 rivers in the Salish Sea from 2000-2010.

Why is it important?

Clean, cold water is critical for streams and rivers where salmon spawn. Even small changes in stream temperature can impact salmon populations.

Poor stream quality can also impact marine water quality by introducing chemical and pathogenHelppathogenA disease-causing microorganism.  pollution, nutrients that can result in algal blooms, and lowering oxygen levels in areas where these streams empty into the sea.

Drinking water, irrigation, recreation, and other uses can also be affected by poor stream quality.

Why is it happening?

Three major factors that affect freshwater are:

  • Stormwater runoff due to increasing development of roads, traffic, parking lots, and other paved areas.
  • Loss of riparian and wetland areas along streams due to development and agricultural operations.
  • Loss of forested areas in the upper watersheds due to timber harvesting.

Recent studies have shown that stream quality can be affected if as little as 7% of the total watershed area is covered by impervious surfaces (e.g. paved areas).

Likewise, the amount of vegetation also plays a role in stream quality. Impacts to stream quality can be observed when vegetative cover (e.g. forested areas) has been reduced to less than 65% of the total watershed area.

What are we doing about it?

Governments, industries, and non-profits are working together to help reduce stormwater runoff from developed land, plant trees along streams, restore wetlands, upgrade aging wastewater treatment plants, and adopt best management practices for agriculture and forestry.

  • Learn more about what we're doing

    Below are examples of the type of work being done by agencies and organizations to help improve stream quality:

    • Environment Canada developed new regulations that establish national standards for sewage treatment. The Canadian Government is also investing in infrastructure so that municipalities can upgrade aging wastewater treatment facilities.

    • British Columbia's Living Water Smart vision for sustainable water stewardship includes actions such as ensuring wetlands and waterways will be protected and rehabilitated, and land activities will not negatively impact our water.

    • Local governments such as MetroVancouver are working with municipalities to develop integrated stormwater management plans and best management in the Georgia Basin. In Puget Sound, local governments are beginning to implement new stormwater permit requirements including the use of Low Impact Development (LID) Stormwater techniques to reduce the impact of stormwater on fresh waters.

    • The Washington Department of Transportation is implementing new stormwater permit requirements to reduce the impacts of stormwater from state highways on fresh water streams.

    • The Washington Department of Ecology is working with regional partners to establish Low Impact Development requirements and providing financial assistance to local governments to implement these new requirements.

    • Washington's Puget Sound Partnership is working with local partners to increase awareness about stormwater runoff, including issues related to pet waste, yard care, vehicle maintenance, and other pollution sources.

Five things you can do to help

  1. Keep streams shaded. Trees and bushes keep the water cool for fish and help stabilize the banks from erosion. Watch for stream restoration projects in your community.
  2. Use techniques such as natural landscaping, rain gardens, rain barrels, green roofs and permeable paving to help reduce the need for chemical fertilizers and reduce runoff.
  3. Never dump unused medicine and chemicals into household toilets and sinks or outside where they can get into ditches or storm drains. See if your community has a household hazardous waste collection facility that will take your old or unused chemicals.
  4. Scoop your pet's poop. Pet waste is full of bacteria that can get washed into waterways during rain storms. Bag it and place it in the trash.
  5. If you keep livestock, follow manure management practices to help reduce agricultural runoff. Contact your local conservation agency for technical assistance.

Learn more about this topic

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Scientific references

  1. Environment Canada. 2011. Freshwater Quality Indicator: Data Sources and Methods. Catalogue Number En4-144/1-2011E-pdf. ISBN 978-1-100-17976-6.
  2. Canadian Council of Ministers of the Environment. 2001. Canadian Water Quality Guidelines for the Protection of Aquatic Life: CCME Water Quality Index 1.0 User's Manual. Winnipeg, Manitoba.
  3. Canadian Council of Ministers of the Environment. 2001. Canadian Water Quality Guidelines for the Protection of Aquatic Life: CCME Water Quality Index 1.0 Technical Report. Winnipeg, Manitoba.
  4. Washington Department of Ecology. 2010. River and Stream Water Quality Monitoring Report: Water Year 2009. Publication Number 10-03-046.
  5. Hallock, D., 2002. A Water Quality Index for Ecology's Stream Monitoring Program. Washington State Department of Ecology, Olympia, WA. 17 pp. + appendices. Publication No. 02-03-052.
  • More references
    1. Hallock, Dave. 2011. Puget Sound Partnership- Setting Targets for Dashboard Indicators: Freshwater Quality Index. Tacoma, Washington.
    2. Environment Canada. 2001. Threats to Sources of Drinking Water and Aquatic Ecosystem Health in Canada. National Water Research Institute, Burlington, Ontario. NWRI Scientific Assessment Report Series Number 1. 72 p.
    3. Northwest Indian Fisheries Commission, 2012. State of Our Watersheds Report. 336 p.
    4. Carlson, K.T. 2001. A Sto:lo Coast Salish Historical Atlas. Published by Sto:lo Nation, Chilliwack, BC and Douglas and McIntyre Ltd., Vancouver, BC. 208p.