South Sound Strategy: Water Quality

Water Quality

Attribute(s) Common to this Focus Area

  • Freshwater Quality
  • Benthic Macroinvertebrate Populations
  • Marine Water Quality


AHSS is interested in improving water quality in freshwater and marine systems over time. Clean freshwater is vital to people and to fish and wildlife populations. When rivers and streams pick up pollutants, toxic contaminants, or excessive sediments and nutrients, the health of watersheds, salmon habitat, and recreational opportunities are adversely affected. Similarly, the opportunity to swim, fish, or dig clams in the South Sound relies on good marine water quality. Marine waters are affected by many different factors including weather and climate, inflow from rivers and streams, stormwater runoff, and discharges from wastewater treatment plants and industries. Excess pollution can force beach closures, shellfish harvesting restrictions, and harmful algae blooms (HAB) that produce toxins that can be dangerous to people, pets and livestock. HAB’s will eventually deplete oxygen levels leading to fish kills.

Status Snapshot

  • Freshwater Quality: The statewide monitoring network has only two stations on waterbodies in the South Sound: (1) Nisqually River at Nisqually, and (2) Deschutes River at East St. Bridge. In 2013, the Nisqually River station scored 83 points on the index and the Deschutes scored 78 points. Water quality scores for both stations have steadily improved between 2000 and 2013. Both stations have averaged 75 points over the period indicating relatively good water quality.
  • Benthic Macroinvertebrate Populations: Based on a review of all available data, stream conditions reported by B-IBI scores range widely throughout the South Sound. B-IBI scores since the late 1990s show improvement of stream conditions for locations in the Upper Nisqually watershed, Goldsborough Creek, Key Peninsula, and Burley Creek areas. Kennedy Creek, Lower Deschutes, and McAllister Creek also show increasing trends in B-IBI scores. However, several areas show decreasing trends in B-IBI scores including Woodland Creek, lower and middle Nisqually watershed, lower Chambers-Clover.
  • Marine Water Quality: In 2014, a composite score of all the South Sound stations received a MWCI score of -2. For individual stations, both Oakland Bay and Budd Inlet received a -12 score. Over time, MWCI scores for the South Sound between 1999 and 2014 indicate the area has experienced a negative change and suggest that marine water quality has gone from good to fair in the past 15 years. Both the Budd Inlet and Oakland Bay stations show negative trends over the period. However the six stations in the Sound show an “improving tendency” as defined by the MWCI. The chart below shows the index scores over the last 15 years.

Key Pressures

  • Changing land cover from natural covers such as forests to more developed status
  • Increasing the amount of impervious surfaces, which leads to changes in stormwater flow and increases pollution in stormwater
  • Pollution from improperly maintained septic systems
  • Pollution from point sources such as wastewater treatment plants, stormwater outfall, and industry sources
  • Pollution from nonpoint sources such as forestry, agriculture, and livestock management
  • Increasing temperatures and precipitation changes related to climate change
  • Pet waste
  • Boating
  • Transportation spills (trucks, trains and ships)
  • Invasive species
  • Residential use of pesticides and fertilizers
  • Emerging contaminants (medicines and home care products not removed by wastewater treatment plants or septic systems)


Freshwater Quality: No new targets at being set at this time; however, AHSS supports local county level targets for water quality improvement and may set a South Sound target in the future.

Benthic Macroinvertebrate Populations: Not at this time.

Marine Water Quality: Not at this time. Maintain or improve the MWCI score for the South Sound monitoring stations.

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