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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 special studies have been conducted in the King County streams. Special studies on the creek are listed at the bottom of this page.


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, 12-acre neighborhood park, is planned for construction in 2006 that will feature a play lawn, sports court, climbing rock, picnic area and children's play area.


Coho salmon, cutthroat and rainbow trout are found in the Monohan subbasin (Kerwin 2001). Volunteers with the Salmon Watcher Program have observed Kokanee, sockeye, and chum salmon in Ebright Creek (King County WLRD April 2005). Coho salmon have also been observed but less commonly.

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. Ebright Creek is now categorized as “Core Summer Salmonid Habitat” for aquatic life use, and “Extraordinary Contact” for recreational use. Ebright Creek is on the Washington Department of Ecology’s (Ecology) 303(d) list (Category 5) for bioassessment scores that indicate that biological integrity is degraded. 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 (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 Ebright 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 1996 to 2018
ParameterNumber of SamplesMeanMinimumMaxmiumMedianStandard Deviation
Dissolved Oxygen (mg/L)22011.27.813.111.10.7
Temperature (°C)2369.
Turbidity (NTU)2362.180.3826.001.462.71
Conductivity (mSIEMS/cm)200148.287.0187.0152.522.4
Total Suspended Solids (mg/L)2365.240.8089.202.958.12
Ortho-Phosphorus (mg/L)2360.03100.01070.05640.03280.0092
Total Phosphorus (mg/L)2360.04490.02700.11200.04300.0113
Ammonia (mg/L)2360.01240.00250.04500.01000.0103
Nitrate (mg/L)2361.29200.42902.09001.34500.3164
Total Nitrogen (mg/L)2361.47420.77001.92001.53000.2210
Fecal Coliform(CFU/100ML)235961680024455

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
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


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

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 web page. To see the benthic macroinvertebrate data for Ebright Creek, please visit the Puget Sound Benthos webpage.

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 Ebright Creek is part of this WRIA 8 planning process.

Ebright Creek Restoration

In 1998 King County completed a project on Ebright Creek to improve fish-passage and enhance habitat on about 300 feet of the creek. The project involved laying back incised streambanks and stabilizing them using bioengineering techniques, and in one area, a rock wall. In-stream log and boulder habitat structures were installed, native riparian vegetation was planted, and a footbridge was replaced.