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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 and sediment samples. From 1975 - 2008 water quality samples were 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.

Watershed

Water Shed Image

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.

Fisheries

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 now categorized as “Core Summer Salmonid Habitat” for aquatic life use, and “Extraordinary Contact” for recreational use. The creek is on the 2012 Washington Department of Ecology’s (Ecology) 303(d) list for violation of dissolved oxygen, temperature, and fecal coliform bacteria standards (Category 5). 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 33-year (1975 – 2007) trend analysis was conduced with baseflow data collected from Fairweather Creek. The analysis showed some improvements in water quality since 1975 with significant decreases in nitrogen, and fecal coliform. However, as with most streams in the County monitoring program, a significant increase in water temperatures occurred and significant decrease in dissolved oxygen were observed during this same time period. In addition, total phosphorus concentrations increased significantly between 1975 and 2007.

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. 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. Routine monitoring summary statistics for this station from 1975 to 2008
ParameterNumber of SamplesMeanMinimumMaxmiumMedianStandard Deviation
Dissolved Oxygen (mg/L)1599.55.512.39.41.6
Temperature (°C)29713.10.923.913.15.0
Turbidity (NTU)3018.510.50470.004.2028.66
pH2117.596.248.507.600.33
Conductivity (mSIEMS/cm)124250.3112.0502.0256.044.8
Total Suspended Solids (mg/L)3009.840.80103.005.8013.85
Ortho-Phosphorus (mg/L)3000.08690.00680.75800.07010.0681
Total Phosphorus (mg/L)3000.14280.01800.79100.12900.0808
Ammonia (mg/L)3010.06900.00700.96300.04560.0934
Nitrate (mg/L)3010.99860.11102.90000.96000.3441
Total Nitrogen (mg/L)2161.51960.77603.73001.44000.4022
Fecal Coliform(CFU/100ML)296685099002201395

Table 2. Storm water monitoring summary statistics for this station from 1975 to 2008
ParameterNumber of SamplesMeanMinimumMaxmiumMedianStandard Deviation
Dissolved Oxygen (mg/L)359.76.512.810.01.7
Temperature (°C)5011.34.220.010.94.0
Turbidity (NTU)5313.192.9337.0011.008.96
pH467.176.508.007.200.33
Conductivity (mSIEMS/cm)21169.981.1228.0167.041.6
Total Suspended Solids (mg/L)5325.213.90160.0015.9027.06
Ortho-Phosphorus (mg/L)530.08580.02450.16300.08340.0341
Total Phosphorus (mg/L)530.18170.09070.52200.17000.0724
Ammonia (mg/L)530.08100.01600.42500.06470.0636
Nitrate (mg/L)530.78440.37901.75000.71800.2982
Total Nitrogen (mg/L)511.58180.85402.72001.52000.4404
Fecal Coliform(CFU/100ML)5319931001000012002190

Hydrology

King County is not currently operating any stream, rain, or temperature gages in Fairweather Creek.

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.

Benthic Invertebrates

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.