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King County Water Quality Monitoring

King County monitors the ecological health of the Pipers Creek basin in a variety of ways including collecting and analyzing water and benthic macroinvertebrate samples. Station KSHZ06 is located at the mouth of the creek, upstream of the railroad tracks before entering the beach area. Water quality sampling at this site began in 1988 and continues today. Station KTHA02 is located just above the confluence of Venema Creek with Pipers Creek. Regular water quality sampling at KTHA02 began in 1988 but was discontinued in 2008 due to budget cutbacks. Station KTHA03 is located at the mouth of Venema Creek. Water quality sampling at station KTHA03 began in 1988 but was discontinued in 2008 due to budget cutbacks. However, regular water quality sampling was reinstated at this station in February 2013. Station KTHA01 is sampled monthly through the marine beach program for select parameters and located upstream of the Carkeek Park treatment facility. King County began collecting benthic macroinvertebrate samples from Pipers Creek in 2010, though this regular sampling will likely decrease in the future.

From time to time additional studies are conducted on Pipers Creek. (Click here for information about Special Studies on Pipers Creek).


Water Shed Image

The Pipers Creek watershed is highly urbanized with a total drainage area of roughly 1,835 acres (Kerwin 2002). The creek and tributaries flow in a northeasterly direction, for combined total length of approximately 5.0 miles, before draining into the Puget Sound estuary at the City of Seattle's Carkeek Park Beach.

The upper portion of the watershed is an urbanized upper plateau occupied primarily by single-family residences with some small businesses and multifamily housing (Kerwin 2002). The upper watershed makes up roughly 80 percent of the Pipers Creek drainage area. Most of the creek runs within the boundary of Carkeek Park in the lower 20 percent of the watershed. Steep ravines, covered with second growth forest, characterize the park.

For more information about the City of Seattle's Carkeek Park, please visit the City of Seattle Park's Department Web site.


Chum salmon, coho salmon, rainbow trout, and coastal cutthroat are known species to inhabit the Pipers Creek (Kerwin 2002). Historically, Pipers Creek and its tributaries had runs of summer/winter steelhead, coastal cutthroat, coho, and chum. The Carkeek Watershed Community Action Project has released coho (1980-83) and chum (1984-present) each spring.

Since 1999 volunteers with the Salmon Watcher Program have been making observations at various locations in the watershed. In Pipers Creek volunteers have consistently seen chum and coho salmon. Less commonly spotted are 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. Piper Creek is now categorized as "Core Summer Salmonid Habitat" for aquatic life use and "Extraordinary Contact" for recreational use.

The water quality in the Pipers Creek was characterized as "good" in 1989 (Metro 1990). And for the most part, water quality conditions in Pipers creek have remained in the moderate to good range. Occasional water quality problems occur as a result of the shifting hillsides due to steepness of the slopes in the park. Over time, these shifts have caused leaks in the sewer lines. In April 2000 there was a small leak from Seattle Public Utilities (SPU) sewer pipe (that eventually hooks up with the King County trunk line) just above the Carkeek Stormwater Facility. In March 2002 a similar incident occurred.

A larger sewage leak occurred from Sept 29- October 4, 2001 when an estimated 2.0 million gallons of wastewater discharged to Puget Sound from the North Beach Forcemain. This break in the line occurred in Carkeek Park where an abandoned SPU line had recently been capped. The County discharged through the North Beach emergency outfall during the repair work rather than have the discharge continue along the shoreline in the park. Because the pipeline was very near the rail-line, it is believed that vibrations from train activity caused a large rock positioned under the pipe to eventually cause the break. Exceedance of fecal coliform bacteria limits continues to be problematic in the creek; Pipers Creek is listed on the 2012 Washington State Department of Ecology's (Ecology) 303(d) list for violation of bacteria standards (Category 4a). 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 these ratings compare with other stream sites, visit the Water Quality Index page.

Table 1. Routine monitoring summary statistics for this station from 1987 to 2018
ParameterNumber of SamplesMeanMinimumMaxmiumMedianStandard Deviation
Dissolved Oxygen (mg/L)25810.87.513.210.80.8
Temperature (°C)36510.31.516.310.52.7
Turbidity (NTU)3214.530.10160.001.9012.53
Conductivity (mSIEMS/cm)227243.550.9285.0255.036.0
Total Suspended Solids (mg/L)35710.280.50294.003.4030.25
Ortho-Phosphorus (mg/L)3630.05480.00600.17900.05540.0137
Total Phosphorus (mg/L)3640.08280.02200.67200.07320.0512
Ammonia (mg/L)3640.02460.00470.26900.01600.0282
Nitrate (mg/L)3631.52630.31102.90001.53000.3099
Total Nitrogen (mg/L)3121.74440.47703.47001.71500.2943
Fecal Coliform(CFU/100ML)3665535400001362353

Table 2. Storm water monitoring summary statistics for this station from 1987 to 2018
ParameterNumber of SamplesMeanMinimumMaxmiumMedianStandard Deviation
Dissolved Oxygen (mg/L)4711.
Temperature (°C)6210.34.015.410.02.7
Turbidity (NTU)5542.322.20925.0015.70125.06
Conductivity (mSIEMS/cm)29142.864.9253.0132.056.5
Total Suspended Solids (mg/L)63103.513.301910.0043.70246.51
Ortho-Phosphorus (mg/L)630.04960.02580.12500.04280.0216
Total Phosphorus (mg/L)630.18000.05751.42000.12100.1945
Ammonia (mg/L)630.05530.01100.30000.04500.0460
Nitrate (mg/L)630.95290.35002.50000.90700.4190
Total Nitrogen (mg/L)611.55740.78204.67001.46000.5625
Fecal Coliform(CFU/100ML)634128443800024005536


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

Stream Sediment

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 Pipers Creek, please visit the Puget Sound Benthos webpage.

Special Studies

King County Beach Assessment Program

King County assists volunteers in collecting information about their local beaches. For information about the beach assessment done at Carkeek Park visit the Carkeek Park page