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King County Water Quality Monitoring

King County monitors the ecological health of Ebright Creek in a variety of ways, including collecting and analyzing water, sediment, and benthic invertebrate samples. Water quality samples are collected monthly from Station A685, located downstream at East Lake Sammamish Parkway SE. Sampling at this site began in 1996 and continued to 2008 when budget cutbacks forced King County to reduce the breadth of its water quality monitoring program. Monthly sampling resumed at this station in February 2013. Sediment samples have been collected from Ebright Creek as part of the Streams Sediment Monitoring Program starting in 1987. King County began collecting benthic macroinvertebrate samples in Ebright Creek in 2002.

From time to time, additional studies have been conducted on Ebright Creek. Click here for more information about Special Studies.

Watershed

Water Shed Image

Ebright Creek is located in the Monohan subbasin on the northeast end of Lake Sammamish in the City of Sammamish. Ebright Creek Park, a 12-acre neighborhood park, features two play structures, a sports court, a picnic shelter, a open grass area, a bathroom facility, and trails.

More than half of total land use in the basin is developed, followed by forest. Developed land is mostly open space and low intensity. However, there is some medium intensity development. Forest is a combination of mixed, evergreen, and deciduous forest. There are no agricultural lands in the basin, and grassland and wetlands make up less than 5% of the basin. Other land uses (grassland) also make up a very small portion of the basin. See Table 1 below for more details on land use.

Table 1. Total land use in the basin

Developed Forest Scrub Wetlands Other
Total 64% 32% <1% 4% <1%

Fisheries

From 1996 to 2015, volunteers with the Salmon Watcher Program observed sockeye and kokanee salmon in Ebright Creek "Stream List," 2016). Coho salmon were also observed, but sightings were rare.

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 (FC) bacteria. 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. Ebright Creek is now categorized as “Core Summer Salmonid Habitat” for aquatic life use, and “Extraordinary Contact” for recreational use. State water quality standards were revised in 2003. Ebright Creek is now categorized as "Core Summer Salmonid Habitat" for aquatic life use and "Extraordinary Contact" for recreational use. As part of the updated water quality standards, portions of Ebright Creek have been assigned additional "Supplemental Spawning and Incubation Protection" temperature criteria of 13 ºC. Ebright Creek is on the Washington State Department of Ecology’s (Ecology) 303(d) list for bioassessment scores that indicate that biological integrity is degraded (Category 5).

See Table 2 below for routine monitoring summary statistics of water quality data collected to date. If stormwater data is available for this site, it will be shown as Table 3. Historical data reviews can be found in the annual reports produced by METRO/King County DNRP.

To view charts of current water quality data, please visit the Data Download webpage.

Water Quality Index

A Water Quality Index (WQI) rating system was developed by Ecology that evaluates several water quality parameters and gives a single rating of “high,” “moderate,” or “low” water quality concern. To see how Ebright Creek ratings compare with other stream sites, please visit the Water Quality Index webpage.

Table 1. Routine monitoring summary statistics for this station from 1996 to 2018
ParameterNumber of SamplesMeanMinimumMaxmiumMedianStandard Deviation
Dissolved Oxygen (mg/L)22711.27.813.111.10.7
Temperature (°C)2439.03.012.69.62.0
Turbidity (NTU)2432.170.3826.001.482.68
pH2417.636.698.107.670.24
Conductivity (mSIEMS/cm)207148.787.0188.0153.022.9
Total Suspended Solids (mg/L)2435.210.8089.202.908.03
Ortho-Phosphorus (mg/L)2430.03090.01070.05640.03280.0092
Total Phosphorus (mg/L)2430.04500.02700.11200.04310.0112
Ammonia (mg/L)2430.01210.00250.04500.00870.0100
Nitrate (mg/L)2431.29110.42902.09001.35000.3176
Total Nitrogen (mg/L)2431.47430.77001.92001.54000.2230
Fecal Coliform(CFU/100ML)242941680024448

Table 2. Storm water monitoring summary statistics for this station from 1996 to 2018
ParameterNumber of SamplesMeanMinimumMaxmiumMedianStandard Deviation
Dissolved Oxygen (mg/L)3711.28.513.910.91.0
Temperature (°C)408.84.712.09.31.9
Turbidity (NTU)4022.280.84272.004.3555.26
pH387.496.807.907.600.27
Conductivity (mSIEMS/cm)33120.964.0172.0128.035.8
Total Suspended Solids (mg/L)4061.521.60629.0012.05132.97
Ortho-Phosphorus (mg/L)400.03460.01230.06720.03960.0138
Total Phosphorus (mg/L)400.10670.03700.58500.06290.1244
Ammonia (mg/L)400.02530.01000.07540.02190.0162
Nitrate (mg/L)401.18360.50301.73001.19500.3265
Total Nitrogen (mg/L)401.57990.87702.84001.63500.3553
Fecal Coliform(CFU/100ML)4036292400175489

Hydrology

King County operates one stream gage on Ebright Creek: Ebright Creek (15h).

Stream Sediment

Sediment data were collected from Ebright 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. Results indicate that Ebright Creek sediments did not exceed any sediment quality guidelines. Of the 27 streams monitored in King County, Ebright Creek had the lowest metals concentration.

Benthic Invertebrates

Benthic macroinvertebrates are small animals visible to the naked eye (macro) that lack a backbone (invertebrate) and live in or around the streambed (benthic). This group includes aquatic insects (such as mayflies and dragonflies), crustaceans, clams, snails, and worms. Benthic macroinvertebrates are of interest to scientists and water resource managers because they are an excellent indicator of the biological health of stream ecosystems and are a critical component of the food web in aquatic communities. Scientists quantify the composition and diversity of benthic macroinvertebrate populations in a stream to compare the biologic integrity of different streams. King County has utilized benthic macroinvertebrate sampling to assess biological health of numerous creeks across the county (see map).

For more information about benthic macroinvertebrates and King County’s Benthic Macroinvertebrate Program, please visit the King County Stream Bug Monitoring webpage. To see the benthic macroinvertebrate data for Ebright Creek, please visit the Puget Sound Stream Benthos webpage.

Special Studies

Lake Sammamish Kokanee Salmon Supplementation Program

The U.S. Fish and Wildlife Service Washington Fish and Wildlife Office, King County, and Washington Department of Fish and Wildlife collaborated on a study to develop and monitor hatchery supplementation strategies to recover native kokanee salmon in Lake Sammamish. Adult kokanee were collected from their natal tributaries, Laughing Jacobs, Ebright Creek, and Lewis Creek and brought to Issaquah State Fish Hatchery where they spawned. Once eggs reached the "eyed-egg" stage, they were placed in three experimental rearing systems using water from the natal tributaries. After the fry emerged from their eggs, they were released in their natal creeks where they could migrate back to Lake Sammamish. In 2010, 14,000 kokanee fry were released. In 2012, more than 18,000 kokanee returned to spawn. In 2018, however, only 19 kokanee returned. The most likely cause for this dramatic decrease is warm water temperatures in the summers of 2014-16 (Kunkler, 2018).

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.