Puget Sound Basin NAWQA

Science Center Objects

The Puget Sound Basin (PUGT) study unit of the National Water Quality Assessment (NAWQA) program encompasses a 13,700-square-mile area that drains to Puget Sound and adjacent marine waters. Included in this region are all or part of 13 counties in western Washington, as well as the headwaters of the Skagit River and part of the Nooksack River in British Columbia, Canada. The Puget Sound Basin contains surface- and ground-water resources of economic and ecological importance. These resources provide water for a large and expanding population, hydroelectric power, recreational opportunities, and an ecosystem that supports an economically important fishery. Surface and ground waters also have the potential to transport nutrients and contaminants to the Puget Sound.

Water-quality issues in the region’s surface waters include loss of aquatic habitat through forestry, agricultural, and land-development practices; contamination of streams and marine waters by point-source discharges and storm washoff of metals, pesticides, and petroleum products from urban and suburban areas; and nutrient enrichment of lakes and Puget Sound embayments.

Map of Puget Sound
Map of Puget Sound(Public domain.)


The U.S. Geological Survey’s National Water Quality Assessment (NAWQA) program provides an understanding of water-quality conditions and how those conditions might vary locally, regionally, and nationally; whether conditions are getting better or worse over time; and how natural features and human activities affect those conditions. The program is designed to take a long-term view of water-quality issues and therefore, study-unit assessments are designed as multiphase water-quality investigations over several years in order to meet this long-term study objective. Click here to read more about the NAWQA Program.

Cycle I

The first cycle of the Puget Sound Basin study-unit assessment was carried out from 1994 – 2003. During those 10 years, the study team identified water-quality issues; accumulated and evaluated existing, historical water-quality data; collected surface- and ground-water quality data; and conducted aquatic ecological surveys. Data analyses and publications of findings were completed in 1999 and 2000. In 2001, the assessment shifted into a low-level data-collection phase with the purpose of tracking long-term trends and identifying emerging water-quality issues prior to beginning a second high-intensity phase in 2004.

1994-1995 Planning, and analysis of existing data

Puget Sound NAWQA Study
Puget Sound NAWQA Study(Public domain.)

1996-1998 Intensive data collection and analysis

1999-2000 Completion of primary reports

2001-2003 Low-level assessment activities

For a summary of Cycle I studies on the quality of ground water and surface water, and studies of aquatic ecosystems, see Circular 1216.

Cycle II

Water-year 2004 marked the beginning of the second cycle of intensive water-quality assessments in the Puget Sound Basin. The intent of NAWQA’s second decade of study is to build on initial water-quality assessments and increase investigations of long-term trends and factors affecting water quality. Cycle II efforts in surface water of the Puget Sound Basin focus on urbanization effects on stream ecosystems in the Puget Lowland ecoregion. Data from 21 streams will be analyzed to determine the magnitude and pattern of hydrologic, chemical, and biological community responses to urbanization and if thresholds exist at which stream ecosystems degrade more rapidly with varying levels of urbanization. In ground water, efforts focus on a second round of data collection from wells in the urban and agricultural land-use study areas. After a 10-year period, approximately 20 wells in the 2 study areas will be re-sampled to build on data for long-term trend analyses.

Tacoma Tide Flats
Tacoma Tide Flats
(Public domain.)

2004-2005 Planning and establishment of study sites

2006-2009 Intensive data collection and analysis

2010 Completion of reports

2011-2013 Low-level assessment activities

For a synopsis of what was learned about streams during Cycle I and future plans for studies during Cycle II, see: Quality of Streamwater in the Puget Sound Basin—A Decade of Study and Beyond


Highlights of Research Conducted by Study-Unit Scientists in the Puget Sound Basin

Highlighs of Ananyses at Regional and National Scales That Include the Puget Sound Basin Study Unit