Bear Creek Site C484

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King County Water Quality Monitoring

King County monitors the ecological health of the Bear Creek basin in a variety of ways including collecting and analyzing water, sediment, and benthic invertebrate samples. Water quality samples have been collected monthly at since 1976 from four stations in Bear Creek. Beginning in 1987, sediment samples have been collected annually at station 0484 of Bear Creek. Benthic invertebrates have been sampled at various locations in the Bear Creek basin beginning in 1995. Station 0484 is located approximately one mile upstream of the mouth of Bear creek where it enters the Sammamish River (the first railroad bridge south of Redmond Fall City Road). Two sites are located on the mainstem of Bear Creek; station C484 is located at bridge number 119A on 95th Avenue (east of Avondale Rd), and station J484 is the furthest upstream site located at the bridge on 133rd (Seidel Rd), 100 yards east of Bear Creek Rd.

From time to time additional studies have been conducted in the Bear Crek basin. Click here for information about Special Studies of Bear Creek.

Bear Creek Watershed

The Bear-Evans Creek basin is comprised of approximately 32,100 acres that includes three sub-basins: Bear Creek at 14,300 acres, Cottage Lake Creek at 8,000 acres, and Evans Creek at 9,800 acres. All together there are over 100+ miles of streams including Bear Creek at approximately 12.4 miles, Cottage Lake Creek at approximately 6.7 miles, and Evans Creek running approximately 8.2 miles (Metro 1990; King County 1989). There are nine lakes and over 2000 acres of wetlands. Local jurisdictions within the basin include: unincorporated King County, unincorporated Snohomish County, City of Redmond, City of Sammamish , and the City of Woodinville.

The headwaters originate at elevations of 180 feet above sea level (Bear Creek) and 100 feet above sea level (Evans Creek). The confluence of the two creeks is at 50 feet above sea level. Bear Creek empties into the Sammamish River on the north side of State Route 520 in the City of Redmond. Widespread permeable gravel and sand fill the valleys of Evans and Bear creeks, allowing them to absorb much of the water from local storm events and the inflowing tributaries (King County 1990; Kerwin 2001).

Land use in the watershed has changed markedly in the past 150 years as development in the area has increased. What was once primarily forest has become a mix of forest, grass, and impervious surfaces. In 1985 the Bear-Evans basin consisted of 71 percent forest, 17 percent grass, 9 percent wetland, and 3 percent effective impervious surfaces (King County 1989).

A unique resource in the Bear-Evans basin is Cold Creek, a cold-water spring. This spring in 5 to 7 degrees centigrade colder than the rest of Bear Creek and is partially responsible for the cooler water temperatures of the Sammamish River downstream of it's confluence during summer and early fall (Kerwin 2001).

Fisheries

The Bear Creek Basin plan, completed in 1990, designated Regionally Significant Resource Areas (RSRAs) along Bear Creek (King County 1990). These areas exhibit high aquatic habitat and salmonid diversity and abundance and a demonstrated contribution to the regional fishery resource. Found in the basin are extensive freshwater mussel populations, freshwater sponges, river otters, crayfish and a good representation of aquatic insects. Because of it’s diversity, the Bear Creek basin was distinguished as one of the top six natural resource basins in King County in the Waterways 2000 program. King County and the City of Redmond have facilitated construction of numerous stream restoration projects identified in the Bear Creek Restoration Plan.

The Bear Creek basin is known to have the following salmonids: chinook, sockeye, coho, kokanee, coastal cutthroat, and steelhead (Kerwin 2001). Since 1996 volunteers with the Salmon Watcher Program have been making observations at various locations in the watershed. In Bear Creek volunteers have consistently seen chinook salmon, coho salmon, kokanee salmon, sockeye salmon and cutthroat trout.

Water Quality

Water quality samples are analyzed monthly for temperature, dissolved oxygen, pH, conductivity, turbidity, total suspended solids, ortho-phosphorus, total phosphorus, ammonia, nitrate-nitrogen, total nitrogen, and fecal coliform 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. Bear Creek was designated a “Class AA” water body under the 1997 rules. As the 2003 rules become effective, the creek is categorized as "Core Summer Salmonid Habitat" for aquatic life use and "Primary Contact" for recreational use. As part of the updated water quality standards, portions of Bear creek has been assigned an additional “Supplemental Spawning and Incubation Protection” temperature criteria of 13 ºC to be applied from September 15th to May 15th. Bear Creek is on the 2004 Washington Department of Ecology’s (Ecology) 303(d) list for violation of dissolved oxygen (DO), temperature, and fecal coliform bacteria (FC) standards. See Table 1 for a summary of water quality violations in the creek during the most recent water year.

Long-term Trends

A 25-year (1979 – 2004) trend analysis was conducted with water quality data collected from all sites in Bear creek. As with most streams in WRIA 8, there has been a significant increase in water temperatures over this 25-year period. Conductivity increased significantly at all sites. Dissolved oxygen decreased at two sites (J484, N484). There have been some improvements in water quality as evidenced by the decrease in total suspended solids (TSS), phosphorus concentrations (ortho and total), and fecal coliform bacteria. Ammonia and total-nitrogen concentrations also decreased at most of the sites. Nitrate concentrations decreased at two sites (J484 and 0484) but increased at C484.

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 Bear Creek stations have been rated “moderate” to “high” concern primarily due to high FC, high nutrients, high temperatures, and low summer DO. To see how these ratings compare with other stream sites, visit the Water Quality Index page.

A review of the 2008 data shows the following violations of State water quality standards:

 

Hydrology

King County maintains fourstreamflow gauges in the Bear-Evans basin: Bear Creek at mouth (02a), Wetland Big Bear Creek #45 Outlet (02b), Bear Creek at 133rd ST NE, near Redmond (02e), Bear Creek at Woodinville-Duvall Rd (02f). King County also maintains one water temperature gauge: Bear Creek at Mouth (02j).

Stream Sediment

Twelve samples were collected along a twelve mile reach of Bear Creek. The cadmium concentration at station Q484 was above levels that could likely cause adverse effects to sediment-dwelling animals. Concentrations of PAHs (combustion byproducts that can be found in vehicle exhaust) and additional metals at stations HH484, Q484, and WW484 suggest that effects associated with these chemicals are uncertain. However, additional data were collected (AVS/SEM ratios) that suggests that metals at these sites are not bioavailable and are unlikely to cause adverse effects at these stations.

Station Q484 is located in a slow moving marshy wetland area of the creek. The sediments at this station are 22 percent fines, indicating that fine sediments as well as contaminants can accumulate in this area. It’s not clear what sources could have contributed contaminants at this site as the upstream area is rural residential and mostly undeveloped. Other than cadmium at this station, Bear Creek exhibits low sediment chemical concentrations, which is likely the result of the lower levels of development in this basin relative to other streams monitored in this program.

Benthic Invertebrates

The County also monitors stream health by collecting samples of benthic invertebrates from selected streams as part of King County's Benthic Invertebrate Program. Benthic invertebrates are an important link in the food chain for fish in the creek and are an excellent indicator of stream health. In both 2002 and 2003, benthic invertebrate samples were collected from Bear Creek and index scores (BIBI) were calculated.

Samples were collected from the main stem of Bear Creek in the upper watershed. BIBI scores for both years characterize conditions for benthic invertebrates in Bear Creek as “fair”. Depending on the site and the year, between 30 and 50 percent of the species identified in the creek were tolerant of degraded conditions. Between 2 and 5 individuals from species that are long-lived were present, and only one individual of a species that is considered intolerant of degraded conditions was present.

Special Studies

Small Streams Toxicity/Pesticide Study

As part of King County’s Small Streams Toxicity/Pesticide Study, pesticide concentrations and toxicity were measured in Bear Creek in 2001. The County collected samples for analysis of pesticides, other organics, metals, suspended solids, and toxicity (Ceriodaphnia dubia, and Selenastrum capricornutum). For more information, visit the pesticide study web site.

Bear Creek Basin Planning

Numerous studies have been conducted in conjunction with basin planning and salmon conservation efforts. King County produced the Bear Creek Basin Current and Future Conditions Analysis Report in 1989 and the Bear Creek Basin Plan in July 1990.For more information about work in the Bear-Evans Creek Basin please visit the Sammamish Watershed page.

Freshwater Mussel Assessment of Bear and Cottage Lake Creeks in 2001.

King County conducted stream habitat assessments in 2001 in Bear Creek and Cottage Lake Creek to characterize the habitat quality, primarily for salmonids. During this habitat assessment, notations were made of freshwater mussel locations, numbers, size, and mussel-bed substrate. This report is intended as a preliminary reconnaissance of the mussel presence in the Bear Creek Basin. Additional surveys were completed in 2004. Investigation of Western Pearlshell Mussel (Margaritifera falcata) Mortality in Bear Creek, King County, Washington: A Disease Ecology Approach