Fairweather Creek Site 0498

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King County Water Quality Monitoring

King County monitors the ecological health of Fairweather Creek in a variety of ways including collecting and analyzing water, sediment, and benthic invertebrate samples. Since 1975 water quality samples have been collected monthly near the mouth of the creek at Station 0498 located at the mouth of the creek near the intersection of Fairweather Place and Hunts Point Place. Sediment samples have been collected from Fairweather Creek as part of the Streams Sediment Monitoring Program starting in 1987.

Fairweather Creek is relatively short, flowing only 1.4 miles before draining into Lake Washington on the east shore. The basin drains roughly 600 acres. Chinook salmon have been observed in the creek (Metro 1990).

From time to time special studies have been conducted at various streams in King County. Special studies on Fairweather Creek are listed at the bottom of this page.

Fairweather Creek Watershed

Fairweather Creek is relatively short, flowing only 1.4 miles before draining into Lake Washington on the east shore. The basin drains roughly 600 acres. Chinook salmon have been observed in the creek (Metro 1990).

Water Quality

Water quality samples are analyzed monthly for temperature, dissolved oxygen (DO), pH, conductivity, turbidity, total suspended solids, ortho-phosphorus, total phosphorus, ammonia, nitrate-nitrogen, total nitrogen, and fecal coliform bacteria (FC). Results are compared to State water quality standards. Water quality standards are designed to protect public health and aquatic life. Comparing monitoring results to water quality standards allows an understanding of how safe the creek is for recreational contact as well as for aquatic life. (See link at top of page to view current water data.)

State water quality standards were revised in 2003. Fairweather Creek is considered a Class AA water body under the 1997 rules. As the 2003 rules become effective Fairweather Creek is categorized as “Core Summer Salmonid Habitat” for aquatic life use, and “Primary Contact” for recreational use. The creek is on the 2004 Washington Department of Ecology’s (Ecology) 303(d) list for violation of dissolved oxygen, temperature, and fecal coliform bacteria standards. See Table 1 for a summary of water quality violations in the creek during the most recent water year.

Fairweather Creek has historically had poor water quality due to its flat topography, the replacement of natural riparian vegetation by residential and golf course landscaping, and enclosure in pipes for almost half its length (Metro 1990).

Long-term Trends

A 25-year (1979 – 2004) trend analysis was conduced with baseflow data collected from Fairweather Creek. The analysis showed some improvements in water quality since 1979 with significant decreases in nitrogen, fecal coliform, and conductivity. However, as with most streams in the County monitoring program, a significant increase in water temperatures occurred during this same time period. In addition, total phosphorus concentrations increased significantly between 1979 and 2004.

Water Quality Index

A Water Quality Index (WQI) rating system was developed by the State Department of Ecology that evaluates several water quality parameters and gives a single rating of “high,” “moderate,” or “low” water quality concern. During the last six water years Fairweather Creek has rated “high concern” primarily due to high FC, nutrients, and temperatures, and low summer DO. To see how Fairweather Creek ratings compare with other stream sites, visit the Water Quality Index page.

To view charts of current water quality conditions in the creek, please visit the links at the top of the page.

Table 1. A summary of violations of State water quality standards for the water year (Oct-Sept) 2007

 

Stream Sediment

Sediment data were collected from Fairweather Creek as part of the Stream Monitoring Program starting in 1987. Data were compiled and analyzed for the years 1987 through 2002. Data were analyzed for trends, correlations, and were compared to sediment quality guidelines.

No significant trends were identified during data analysis for any of the parameters tested for Fairweather Creek sediments. Results indicate that Fairweather Creek exceeded three sediment quality guidelines (lead, nickel, and zinc). It is unclear why concentrations of these metals exceed sediment quality in this creek. However, it is possible that the proximity of Highway SR520 is a source of these contaminants as these three metals have been associated with runoff from street and highways. Of the 27 streams monitored in King County, Fairweather Creek had the 4th highest metals concentrations.

Special Studies

Water Resources Inventory Area (WRIA) 8

In WRIA 8, citizens, scientists, businesses, environmentalists and governments are cooperating on protection and restoration projects and have developed a science-based plan to conserve salmon for future generations. Visit the WRIA 8 page to see how Fairweather Creek is part of this WRIA 8 planning process.