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King County Water Quality Monitoring

King County has monitored the ecological health of the George Davis Creek (often called Eden Creek) basin in a variety of ways including collecting and analyzing water, sediment, and benthic invertebrate samples. From 1987 - 2008 water quality samples were collected monthly from Station A690 located at 635 East Lake Sammamish Shore Lane, downstream from the railroad tracks. Water quality sampling resumed at this site in 2014. Sediment samples were collected from the creek as part of the Streams Sediment Monitoring Program starting in 1987. King County began collecting benthic macroinvertebrate samples in George Davis (Eden) Creek in 2002.

Watershed

Water Shed Image George Davis Creek (also shown as Eden Creek on some maps) is within the City of Sammamish in the Inglewood subbasin on the northeast side of Lake Sammamish in the City of Sammamish. Land use along the inaccessible stream reaches is a mix of residential development and intact green space

Fisheries

Only about 100 feet of George Davis Creek is currently accessible to kokanee and provides potential spawning habitat as the connection between George Davis (Eden) Creek and the lake is highly altered.

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. George Davis (Eden) Creek is now categorized as “Core Summer Salmonid Habitat” for aquatic life use, and “Extraordinary Contact” for recreational use. The creek (as Eden Creek) is on the Washington Department of Ecology's (Ecology) 303(d) list, Category 5, for violation of fecal coliform bacteria standards. See Table 1 for a summary of water quality violations in the creek during the most recent water year.

Water Quality Index

A Water Quality Index rating system was developed by the State Department of Ecology that evaluates several water quality parameters and gives and overall rating of “high,” “moderate,” or “low” concern. To see how George Davis (Eden) 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 1987 to 2018
ParameterNumber of SamplesMeanMinimumMaxmiumMedianStandard Deviation
Dissolved Oxygen (mg/L)19411.28.713.011.30.8
Temperature (°C)2269.82.181.09.35.3
Turbidity (NTU)2292.900.2845.001.454.94
pH2247.596.618.607.600.26
Conductivity (mSIEMS/cm)173130.470.0166.0135.024.3
Total Suspended Solids (mg/L)2297.820.50274.002.7021.53
Ortho-Phosphorus (mg/L)2290.02060.00900.04590.02190.0070
Total Phosphorus (mg/L)2290.03360.01220.18900.03030.0191
Ammonia (mg/L)2290.01270.00200.04220.01000.0117
Nitrate (mg/L)2281.99290.90402.85002.08000.3786
Total Nitrogen (mg/L)2272.10480.68203.05002.20000.4117
Fecal Coliform(CFU/100ML)22770076024116

Table 2. Storm water monitoring summary statistics for this station from 1987 to 2018
ParameterNumber of SamplesMeanMinimumMaxmiumMedianStandard Deviation
Dissolved Oxygen (mg/L)1911.410.112.611.30.6
Temperature (°C)299.07.411.88.81.2
Turbidity (NTU)2946.790.90820.003.30158.41
pH297.446.808.007.500.28
Conductivity (mSIEMS/cm)15100.055.0135.091.024.9
Total Suspended Solids (mg/L)29152.141.702990.0010.00559.94
Ortho-Phosphorus (mg/L)290.02150.01090.05350.01520.0120
Total Phosphorus (mg/L)290.14420.01572.01000.03730.3757
Ammonia (mg/L)290.05900.02400.13300.04200.0436
Nitrate (mg/L)291.78490.90302.19001.79000.2895
Total Nitrogen (mg/L)292.08120.97503.84002.03000.5044
Fecal Coliform(CFU/100ML)292300410032758

Hydrology

King County is not currently operating any stream, rain, or temperature gages in George Davis/Eden Creek.

Stream Sediment

Sediment data were collected from George Davis (Eden) 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 State water quality standards sediment quality guidelines. No significant trends were identified during data analysis for any of the parameters tested. Results indicate that Eden Creek sediments did not exceed any sediment quality guidelines. Of the 27 streams monitored in King County, George Davis (Eden) Creek had the 10th lowest metals concentration.

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 State water quality standards WRIA 8 page to see how Eden Creek is part of this WRIA 8 planning process.