Swamp Creek Site 0470

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King County Water Quality Monitoring

King County monitors the ecological health of Swamp Creek in a variety of ways including collecting and analyzing water, sediment, and benthic invertebrate samples. Station 0470 is located at the USGS Gaging station near Bothell Way and 80th Ave North. Water quality samples have been collected monthly at this station since 1976. In 1999 the county began monitoring another site on Swamp Creek (BB474) located at Carter Road. Beginning in 1987, sediment quality samples have been collected from Swamp Creek. In 2002 King County began a benthic invertebrate monitoring program that included samples collected from Swamp Creek.

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

Swamp Creek Watershed

Swamp Creek originates in the Paine Field and West Casino Road area of South Everett. Extensive wetlands once dominated the headwaters of Swamp Creek. The upper reaches still have some large good-quality wetlands and high-quality salmonid spawning and rearing habitat, as well as one of the largest populations of freshwater mussels found in the Puget Sound Lowlands (King County WLRD, May 2001). The creek flows roughly 10.9 miles southward into King County, where it empties into the Sammamish River just upstream of its outlet into Lake Washington.

The Swamp Creek basin is approximately 15,000 acres, and roughly 52 percent of the drainage is impervious and 19 percent forested cover. The drainage basin includes Scriber Lake, Martha Lake, and Lake Stickney and drains portions of Lynnwood, Everett, Brier, Bothell, Mountlake Terrace, Kenmore and unincorporated Snohomish County.

Streambank stability was found to be generally poor throughout Swamp Creek during a recent habitat survey (King County WLRD, May 2001a). Streambank stability ratings in many segments were related to the riparian corridor condition. Segments in the upper reaches of the watershed tended to have more stable streambanks than the middle and lower reaches.

Increased urbanization has resulted in peak flows of greater intensity and duration, lower summer flows, increased flashiness, over-widening of the stream channel, bank erosion, and scour of the streambed (Kerwin, 2002). Increased frequency of flood flows from 1964 - 1990 were found to coincide with urbanization over the same period.

Fisheries

Since 1997 volunteers with the Salmon Watcher Program have been recording salmon observations at various locations in Swamp Creek. Volunteers have consistently seen coho in the creek. Less commonly spotted are kokanee and sockeye salmon. Observers have not seen chinook salmon.

The salmonid habitat quality of Swamp Creek was evaluated by King County from August to November 1999 (see Special Studies section below). The middle stream reaches tended to be higher quality than the upper and lower segments. Most segments fell primarily in the low and medium-low habitat quality categories, although three segments were rated medium-high. Chinook redds were not found in Swamp Creek during the 1999 King County assessment ((King County WLRD. 2000a); however, juvenile salmonids, including coho and cutthroat, were observed in many segments during the 1999 habitat surveys ((King County WLRD. 2001a).

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. Swamp Creek was considered a “Class AA” water body under the 1997 rules and categorized as “Core Salmon Migration and Rearing Habitat” for aquatic life use and “Primary Contact” for recreational use under the 2003 rules. As part of the updated water quality standards, the creek has been assigned an additional “Supplemental Spawning and Incubation Protection” temperature criteria of 13 ºC to be applied from September 15th through May 15th. Swamp Creek is on the 2004 Washington Department of Ecology’s (Ecology) 303(d) list for violation of dissolved oxygen and temperature standards. See Table 1 for a summary of water quality violations in the creek during the most recent water year.

Long-term Trends

A 28-year (1979 – 2007) trend analysis was conducted with water quality data from station 0470 in Swamp Creek. Results indicated that water quality might have declined over this 28-year period with significant increases in water temperatures, total phosphorus, and conductivity. High conductivity can suggest the presence of unidentified dissolved charged substances in the water. Dissolved oxygen concentrations have also decreased significantly. Water at the mouth of Swamp Creek is becoming more acidic as indicated by the significant decrease in pH. (The pH remains within acceptable range relative to the state standards.) Decreased total suspended solids (TSS), nutrients (ortho-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. During the last seven water years station 0470 at the mouth of Swamp Creek were rated “high” concern, while upstream at BB474 ratings were “moderate” to “high” concern. High concern ratings were due primarily to high fecal coliform bacteria levels and high nitrogen concentrations. 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 two water temperature gauges: Swamp Creek located on north-east side of creek underneath bridge near Burke-Gilman trail at RM 0.44 ( 56A), and Swamp Creek located on north-west side of creek west of Locust Rd. bridge at RM 5 (56C) and one streamflow gauge: Swamp Creek (56b) on Swamp Creek.

Stream Sediment

Sediment data were collected from Swamp Creek as part of the Streams Sediment 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 sediments in Swamp Creek did not exceed any sediment quality guidelines. Of the 27 streams monitored in King County, Swamp Creek had the 8th lowest metals concentration.

Benthic Invertebrates

The county monitors stream health by collecting samples of benthic invertebrates from selected streams as part of King County's Benthic Macroinvertebrate 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 2002, 2003, and 2006, benthic invertebrate samples were collected, analyzed, and benthic invertebrate index scores (BIBI) were calculated for Swamp Creek. Samples were collected from two locations in 2002 and 2006, and one sample was collected in 2003. BIBI scores for both sites analyzed in 2002 were 22, indicating that conditions in Swamp Creek for benthic invertebrates were “poor” (the poor designation ranges from 18-26). However, in 2003 the score was 28 and in 2006 the scores were 28 and 32 indicating conditions for benthic invertebrates were “fair” (the fair designation ranged from 28 to 36 with the higher number indicating better quality). While the increase in the score for Swamp Creek can be taken as good news, it is unclear if this improvement is part of a trend or is caused by some other phenomena such as sampling variability. It will be interesting to these scores over time.

Special Studies

Habitat Inventory and Assessment

From August to November 1999, King County conducted habitat assessment on North, Swamp, and Little Bear creeks (King County WLRD, May 2001). These streams are the major three northern tributaries to the Sammamish River. The Swamp Creek habitat assessment took place from the mouth of the creek to 380 meters north of 164th Street S.E. in Snohomish County. Click here to download the Habitat Inventory and Assessment for North, Swamp, and Bear Creeks (PDF format).

The results of the habitat assessments indicate that the channel and habitat structure of a number of the segments in all three streams are frequently degraded relative to values from published "properly functioning conditions" for the Puget Sound or the Pacific Northwest region. These data provide important baseline information for any restoration projects that might occur in the basins, as well as for monitoring changes in habitat quality. This study may be used for a limiting factor analysis for the threatened chinook salmon as well as other salmonid species in these basins.

Small Streams Toxicity/Pesticide Study

In 1999, King County conducted a pesticide study on Lyon, Juanita, and Lewis creeks. In 2000 the study was repeated at Lyon, Swamp, and Little Bear creeks. In 2001, Big Bear and Issaquah Creeks were sampled. And in 2002, North, Little Bear, and the 124th street Creeks were sampled. Rock Creek was tested for pesticides in 1999 and then it was used as the reference stream for toxicity testing during each year of the study. The County collected samples for pesticides, other organics, metals, suspended solids, and toxicity (Ceriodaphnia dubia, and Selenastrum capricornutum). For more information, visit the pesticide study Web site.

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.