Stream report for
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Little Bear Creek-0478
Little Bear Creek-S478
Middle Fork Snoqualmie-MFk_Snq
North Fork Snoqualmie-NFk_Snq
Pine Lake Creek-A680
South Fork Snoqualmie-SFk_Snq
King County Water Quality Monitoring
King County monitors the ecological health of Longfellow Creek in a variety of ways including collecting and analyzing water, sediment, and benthic invertebrate samples. Since 1979 water quality samples have been collected monthly from Station C370 located at the footbridge on SW Yancy Street, near 28th Ave SW. In 1992 another water quality station (J370) was added further upstream at Brandon Street.
From time to time special studies have been conducted at various streams in King County.
Click here for information about Special Studies of Longfellow Creek.
The Longfellow Creek subbasin is comprised of roughly 2,685 acres in West Seattle within the Water Resource Inventory Area (WRIA 9). The creek flows for approximately 4.2 miles through heavily urbanized areas into the West Duwamish Waterway ( Kerwin and Nelson 2000). Currently, the upper 4,900 feet of the creek has been diverted into underground pipes and roughly one third of the total creek flow drains through pipes beneath shopping centers, houses and roads.
The headwaters of Longfellow Creek were historically located in a natural wetland and peat bog in what is now Roxhill Park. (
Kerwin and Nelson 2000). The Roxhill bog was recently restored with the completion of the Longfellow Creek Legacy Trail in West Seattle. For more information about the Longfellow Creek watershed and restoration efforts visit the local community and the City of Seattle’s Web sites
Historically, Longfellow Creek contained populations of coho salmon, cutthroat trout and steelhead trout (
Kerwin and Nelson 2000). In 1999, Seattle Public Utilities conducted spawning surveys on Longfellow creek and noted the presence of sixty adult coho salmon. In addition, juvenile rainbow trout and coho salmon were captured during electrofishing surveys in 1999 by Washington Trout. Numerous groups have released coho fry into the creek over the years.
Longfellow Creek has two small-unnamed tributaries. These tributaries are believed to be too small for anadromous fish use, but may be important refuge for over wintering salmonids during periods of high flow.
Key findings in the Habitat-limiting Factors and Reconnaissance Report (
Kerwin and Nelson 2000) identified extensive channelization, severely altered hydrologic regime, lack of instream structures, habitat barriers, quality and quantity of gravels, and poor water quality as some of the factors affecting anadromous fish in Longfellow Creek.
Beginning 2001, NOAA’s Northwest Fisheries Science Center has been studying coho pre-spawn mortality in urban streams of the Puget Sound Basin. Longfellow Creek is part of this study. Fish suffering from pre-spawn mortality show behavioral symptoms that are indicative of an underlying neurological or respiratory disorder. Fish with the disorder exhibit loss of orientation, followed by loss of equilibrium, and eventual death.
Volunteers in the
King County Salmon Watcher Program have been making observations in Longfellow Creek beginning 1999 and have consistently sighted coho and chum salmon. Chinook salmon and cutthroat trout have also been spotted on occasion.
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. Longfellow Creek is considered a “Class A” water body under the 1997 rules. As the 2003 rules become effective Longfellow Creek is categorized as “Salmonid Spawning, Rearing and Migration Habitat” for aquatic life use. The creek is designated as “Primary Contact” for recreational use. Both sampling sites are listed on the 2004 Washington Department of Ecology’s (Ecology) 303(d) list for violation of DO and FC standards. See Table 1 for a summary of water quality violations in the creek during the most recent water year.
A 2000 water quality data review summarized characterized Longfellow creek as having “fair” water quality for aquatic life (Kerwin and Nelson 2000). Under base flow conditions water quality criteria were generally met. However, criteria for copper and temperature were occasionally exceeded, and pH levels were below criteria under storm flow conditions.
To view charts of current data for Longfellow Creek, visit the links above.
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. Longfellow Creek stations have been rated “high” to “moderate” concern during the last six water years water years. High nutrient concentrations and high fecal coliform bacteria compromise water quality in the creek. To see how Longfellow Creek ratings compare with other stream sites, visit the
water quality index page.
A 25-year (1979 – 2004) trend analysis was conducted with baseflow water quality data from station C370 showed some significant changes in the water quality since 1979. Improvements in water quality over this time period are indicated by a significant decrease in temperature and an increase in dissolved oxygen concentrations. Water in Longfellow Creek is becoming more acidic as indicated by the significant decrease in pH. However, the pH remains within acceptable range relative to the state standards. Water quality declined with regards to nutrient enrichment as there was a significant increase in total phosphorus and total nitrogen.
Table 1. Routine monitoring summary statistics for this station from 1992 to 2008
Parameter Number of Samples Mean Minimum Maxmium
Median +/- stdev
Dissolved Oxygen (mg/L) 119 9.9 6.5 11.9 8.8 - 11.0
Temperature (oC) 204 10.9 3.0 19.2 7.6 - 14.3
Turbidity (NTU) 219 5 0 93 -4 - 15
pH 162 7.6 5.2 8.9 7.2 - 8.0
Conductivity (mSIEMS/cm) 104 284 125 329 237 - 331
Total Suspended Solids (mg/L) 188 6.9 0.5 203.0 -13.8 - 27.5
Ortho-Phosphorus (mg/L) 218 0.036 0.007 0.371 0.001 - 0.070
Total Phosphorus (mg/L) 219 0.070 0.014 0.555 0.003 - 0.137
Ammonia (mg/L) 179 0.058 0.007 1.750 -0.157 - 0.273
Nitrate (mg/L) 217 1.081 0.369 2.580 0.813 - 1.349
Total Nitrogen (mg/L) 219 1.390 0.190 5.520 0.824 - 1.957
Fecal Coliform(CFU/100ML) 211 1078 10 39000 -2387 - 4543
Longfellow Creek Restoration Activities
For information about restoration efforts within the Longfellow Creek subbasin, visit the
community Web site.
Coho Pre-spawn Mortality in Urban Streams
Research scientists in
NOAA's Ecotoxicology and Environmental Fish Health Program are actively investigating the problem of coho pre-spawn mortality in urban streams of the Puget Sound Basin.