Sammamish River Site 0450

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King County Water Quality Monitoring

King County monitors the ecological health of the Sammamish River in a variety of ways including collecting and analyzing water, sediment, and benthic invertebrate samples. Station 0486 is located at the Marymoor Park Bridge where Lake Sammamish drains into the Sammamish River. Station 0450 is located at the bridge on 68th Avenue Northeast in Kenmore where the river drains into Lake Washington. Water quality samples have been collected monthly at these stations since 1971. The County also has stations along the major tributaries to the Sammamish River - Swamp Creek, North Creek, Bear Creek, and Little Bear Creek.

From time to time additional studies have been conducted at various streams in King County. (Click here for information about Special Studies of Sammamish River.)

Sammamish River Watershed

The Sammamish River basin drains a watershed composed of approximately 153,600 acres that includes 62,080 acres in the Lake Sammamish basin, 32,000 acres in the Bear Creek basin, and 42,880 acres that are the combined Little Bear, Swamp, and North creek basins. The remaining 16,640 acres comprise the Sammamish River subbasin.

Historically, the Sammamish River was approximately twice as long as it is today with abundant “swampy” areas that were filled with peat and diatomaceous earth (Kerwin 2002). The river corridor was heavily logged from the 1870s through the early 20th century. Throughout the 20th century, the river went through dramatic changes that reduced the complexity of the floodplain including the lowering of the Lake Washington, the channelization of the river, and the construction of drainage ditches in the river valley. The elevation of Lake Washington was lowered about 9 feet with the opening of the Chittenden Locks in 1916, and this elevation change drained much of the swampy Sammamish River corridor (Stickney and McDonald 1977; Martz, et.al. 1999). Around the same time period, farmers in the Sammamish River Valley formed a drainage district that began to straighten the upper reach of the river dramatically (King County 1911; Kerwin 2002). The Corps of Engineers began in 1962 to systematically dredge and channelize the river, primarily as a flood control project, thus deepening the river 5 feet throughout most its length, hardening the river’s banks, and dramatically decreasing its remaining connection with the floodplain and cutting off most of the smaller tributaries to the river (Martz, et.al. 1999; Kerwin 2002).

The Sammamish River is now 15.3 miles long. The upper river corridor extends from the head of the river at River Mile (RM) 15.3 north to RM 4.9 through a floodplain valley that is more than a mile wide in places. Land use in this upper reach includes open space and recreational areas at Marymoor Park, urban commercial and residential development in the City of Redmond, the Willows Run Golf Course, the Sammamish Valley Agricultural Production District and urban development again in the City of Woodinville (Kerwin 2002). The lower reach extends from R.M. 4.9 to the mouth of the river (R.M. 0) at Lake Washington. This reach has a much narrower drainage area, which includes the downtown cores of Bothell and Kenmore but also some open space areas, including the Wayne and Inglemoor Country club golf courses, Bothell parkland along the Sammamish River Trail, and King County-owned parcels at the mouth of Swamp Creek and the mouth of the river. A major King County sewer line runs underneath the Sammamish River Trail, which is adjacent to most of the river.

Fisheries

Chinook, coho, sockeye, kokanee, steelhead, and coastal cutthroat are known salmonid species to currently inhabit the Sammamish River system (Kerwin 2002). The United States Fish and Wildlife Service has identified the river and its tributaries as potential foraging habitat for bull trout on the assumption that they are found in the watershed. Volunteers with the Salmon Watcher Program have been making observations at various locations within the Sammamish River basin since 1997.

Two salmon-bearing tributary systems are located in the upper reach: Bear Creek and Little Bear Creek. The lower reach includes two large salmon-bearing tributaries: Swamp Creek and North Creek (Kerwin 2002).

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. The Sammamish River was considered a “Class AA” water body under the 1997 rules. As the 2003 rules become effective the Sammamish River is categorized as “Core Salmon Migration and Rearing Habitat” for aquatic life use and “Primary Contact” for recreational use. The river is on the 2004 Washington Department of Ecology’s (Ecology) 303(d) list for violation of fecal coliform and water temperature standards. The river is also listed for violations of the dissolved oxygen standards (shall exceed 9.5 mg/L). Dissolved oxygen levels decrease when the temperatures increase. In addition, high nutrient (phosphorus and nitrogen) concentrations can exacerbate low oxygen conditions by increasing vegetative growth. Decaying vegetation consumes oxygen in the water.

Diazinon and other chemicals have been found in one irrigation and drainage ditch feeding the river at levels that are of concern (Wilson 2001). King County has done additional toxicity studies of the river (see Special Studies section below).

Long-term Trends

A 28-year (1979 – 2007) trend analysis was conducted with water quality data from both Sammamish River stations. Results indicated that water quality might have declined over this 28-year period with significant increases in water temperatures and conductivity, and decreasing dissolved oxygen concentrations. High conductivity can suggest the presence of unidentified dissolved charged substances in the water. Water at the mouth of the river is becoming less acidic as indicated by the significant increase in pH. (The pH remains within acceptable range relative to the state standards.) Decreased total suspended solids (TSS), turbidity, nutrients (ortho- and total phosphorus, ammonia and total nitrogen), and bacteria levels indicate some improvements in water quality in the same 28-year period.

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. Station 0450 was rated “high” concern for the last six water years, while Station 0486 was rated “moderate” concern until 2006-07 then its rating decreased to “high” concern. High concern ratings were due primarily to high temperatures and low dissolved oxygen concentrations. To see how these ratings compare with other stream sites, visit the Water Quality Index page.

A review of the water year 2007 data shows the following violations of State water quality standards:

 

Hydrology

King County maintains five streamflow gauges on the Sammamish River: Sammamish River Tributary 0057C , Norway Creek (51a) , Sammamish River Tributary 0096D off NE 145th ST (51c), Sammamish River Tributary 0090 at NE 145th ST (51d), Sammamish River Tributary 0095B at NE 124th ST (51e), and Sammamish River Trib 0141 (51G ),

King County also maintains five temperature gauges on the Sammamish River: Sammamish River east side attached to upper Redmond RR bridge support (51L), Sammamish River at Marymoor Weir (51m), Sammamish River at Powerlines (51n), Sammamish River at West Park Entrance (51p), and Sammamish River south side in middle support of lower Woodinville RR bridge (just above Little Bear Creek) (51R)

Special Studies

• Sammamish River Diurnal Dissolved Oxygen and pH Study

The study was designed to provide adequate spatial and temporal resolution of DO and pH along the river for use in modeling the Sammamish River. Stations at seven locations along the Sammamish River (including the upstream boundary) as well as one station on Big Bear Creek near the mouth were monitored.

• Endocrine Disrupting Chemicals (EDCs) Survey

New information is emerging about the natural and synthetic chemicals people dispose of every day in their sinks and toilets. The purpose of this survey was to determine if EDCs would be found at detectable levels within the Elliott Bay/ Central Puget Sound/ Duwamish estuary and the lakes, major rivers, and some tributaries in the Green, Cedar, and Sammamish rivers. Samples were collected at each location once per quarter in 2003; this method generated 4 samples per site collected throughout all seasons.

• Sammamish River Sediment and Water Quality Assessment

The primary purpose of this assessment was to obtain baseline information and evaluate the concentration and distribution of potential contaminants of concern in Sammamish River surface water and sediment. Water sampling was conducted in early September 2001, and sediment sampling was conducted in early October 2001. Samples were analyzed for metals, organic compounds (including pesticides), and conventional parameters. In addition, water samples were analyzed for a number of parameters using USGS's wastewater method that included analysis for chemicals classified as endocrine disrupters. Water quality monitoring was also conducted in the fall of 2002. Sediment chemistry and benthic community structure was conducted in 2003.

• Sammamish River Corridor Action Plan

King County Department of Natural Resources and the US Army Corps of Engineers were partners in the preparation of the Sammamish River Action Plan. The report was prepared in close coordination with local municipalities and stakeholders and provides guidance on restoration needs and projects for the Sammamish River Corridor. The plan focuses on the Sammamish River's role as a necessary migratory corridor for anadromous salmon in the Sammamish Watershed. The fundamental goal of the Plan is to make the Sammamish River Corridor a strong link, rather than a weak one, in this larger ecosystem.

• Sammamish River Restoration at NE 124th

The goal of this project was to enhance riparian habitat by clearing invasive plant species and replacing them with natives. Contact: Doug Chin for more information.

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 today and for future generations. Visit the WRIA 8 Web page to see how this creek is part of this WRIA 8 planning process.