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King County Water Quality Monitoring

King County monitors the ecological health of Crisp Creek in a variety of ways including collecting and analyzing water, sediment, and benthic invertebrate samples. Station 0321 is located at the mouth of the creek at the bridge on Southeast Green Valley Road, west of 212th Place SE. Water quality samples were collected monthly at this station from 1972 to 2008 when budget cutbacks forced King County to reduce the breadth of its water quality monitoring program. Sampling at this station resumed in February 2013. In 1993 the County began collecting water quality samples at an additional site on Crisp Creek (F321) located upstream of the hatchery inflow near SE 348th and 215th Avenue SE. Sampling at this station was discontinued in 2008 due to the aforementioned budget issues, but resumed in February 2013. In 2017 the Upper Crisp Creek station was moved upstream roughly 100 feet due to construction in the area, and was renamed FF321. Beginning in 1987, sediment quality samples have been collected from Crisp Creek. King County began collecting benthic macroinvertebrate samples in Crisp Creek in 2002.

From time to time additional studies have been conducted on Crisp Creek. Click here for information about Special Studies of Crisp Creek.


Water Shed Image The Crisp Creek watershed is located in South King County between the cities of Black Diamond and Maple Valley and drains roughly 3,200 acres. The creek originates from several groundwater springs, including Keta Creek Springs and a 20-acre bog at approximately 600 feet in elevation (Kerwin and Nelson, 2000; Muckleshoot Indian Tribe, March 1992). The creek runs for a total of three miles from the natural plateau, over the topographic break, and then parallel to the Green River before entering it at River Mile 40.1. Two lakes, Horseshoe Lake and Keevies Lake, are located within the Crisp Creek basin.

The upper reaches of Crisp Creek are forested where the stream traverses through commercial timberlands. Downstream of the commercial timberlands the riparian area becomes wider with mostly deciduous trees. The lower reach of the creek, below the fish hatchery, includes several farms and a few single-family homes.


Crisp Creek provides spawning and rearing habitat for coho, chinook, chum and winter steelhead (Kerwin and Nelson, 2000). Crisp Creek serves as the water supply for the Keta Creek Hatchery (operated by the Muckleshoot Indian Tribe) and two former Washington Department of Fish and Wildlife rearing ponds located at approximately River Mile 1.05. The hatchery rears and releases chum, coho, chinook, and winter steelhead (released off-station).

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. Crisp Creek is now designated “Core Summer Salmonid Habitat” for aquatic life use, and “Primary Contact” for recreational use. As part of the updated water quality standards Crisp Creek has been assigned an additional “Supplemental Spawning and Incubation Protection” temperature criteria of 13 ºC to be applied from September 15th to July 1st. The creek is on the 2012 Washington Department of Ecology’s (Ecology) 303(d) list, Category 5, for violation of dissolved oxygen standards. See Table 1 for a summary of water quality violations in the creek during the most recent water year.

Crisp Creek has historically had few water quality concerns due to the relatively undisturbed, forested condition of the drainage basin (Herrera 2005).

Long-term Trends

A 25-year (1979 - 2004) trend analysis was conducted with water quality data from station 0321 in Crisp Creek. Results indicated that water quality might have declined over this 25-year period with significant increases in water turbidity, ortho-phosphorus and fecal coliform bacteria. Decreased nitrate and total nitrogen concentrations indicate there may be some improvements in water quality in the same 25-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 and overall rating of "high", "moderate", or "low" concern. To see how Crisp Creek ratings compare with other stream sites, visit the Water Quality Index page page.

For more information about long-term trends in water quality and to view charts of current water quality conditions in the creek, please visit the links at the top of the page.

Table 1. Routine monitoring summary statistics for this station from 1972 to 2018
ParameterNumber of SamplesMeanMinimumMaxmiumMedianStandard Deviation
Dissolved Oxygen (mg/L)20310.56.212.310.50.9
Temperature (°C)2599.
Turbidity (NTU)2572.930.5064.001.705.66
Conductivity (mSIEMS/cm)175121.288.6146.0121.010.8
Total Suspended Solids (mg/L)2597.690.7084.804.2011.79
Ortho-Phosphorus (mg/L)2590.02660.00820.08310.02400.0115
Total Phosphorus (mg/L)2590.05040.01260.17200.04380.0264
Ammonia (mg/L)2590.09390.01200.52600.07190.0743
Nitrate (mg/L)2590.77190.51701.70000.75700.1458
Total Nitrogen (mg/L)2551.04130.35202.61000.99200.2774
Fecal Coliform(CFU/100ML)2587837504697

Table 2. Storm water monitoring summary statistics for this station from 1972 to 2018
ParameterNumber of SamplesMeanMinimumMaxmiumMedianStandard Deviation
Dissolved Oxygen (mg/L)4310.17.711.610.30.9
Temperature (°C)639.66.412.49.81.5
Turbidity (NTU)634.980.5235.303.005.84
Conductivity (mSIEMS/cm)26118.286.0138.0120.016.1
Total Suspended Solids (mg/L)6310.471.8055.007.6010.08
Ortho-Phosphorus (mg/L)630.02890.01400.05370.02770.0086
Total Phosphorus (mg/L)630.06280.02800.15900.05690.0266
Ammonia (mg/L)630.10010.01800.19200.10100.0479
Nitrate (mg/L)630.85730.55402.09000.80000.2740
Total Nitrogen (mg/L)621.20270.63902.45001.09500.3872
Fecal Coliform(CFU/100ML)6348244100190820


King County maintains two streamflow gauges on Crisp Creek, one near Black Diamond (40b) and one at Green River Road (40d).

Stream Sediment

Sediment data were collected from Crisp Creek as part of the Stream 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 Crisp Creek sediments did not exceed any sediment quality guidelines. Of the 27 streams monitored in King County, Crisp Creek was in the middle with the 13th highest metals concentration.

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 Crisp Creek, please visit the Puget Sound Benthos webpage.

Special Studies

Green-Duwamish Water Quality Assessment

In 2001 King County initiated a separate comprehensive study of the Green-Duwamish Watershed, called the Green-Duwamish Watershed Water Quality Assessment (GDWQA). Several reports evaluate data collected as part of the GDWQA. Crisp Creek is included in this analysis. More information about the GDWQA, as well as the reports, can be found at the Green-Duwamish Water Quality Assessment Web site.