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King County Water Quality Monitoring

King County monitors the ecological health of Newaukum Creek in a variety of ways including collecting and analyzing water, sediment, and benthic invertebrate samples. Since 1972 water quality samples have been collected 1 mile upstream from the mouth of Newaukum Creek at station 0322, located at the USGS gauging station near the bridge at 212th SE Street. Sediment samples have been collected from Newaukum Creek as part of the Streams Sediment Monitoring Program starting in 1987. King County began collecting benthic macroinvertebrate samples in Newaukum Creek in 2002.

From time to time additional studies have been conducted at various streams in King County. Click here for information about Special Studies of Newaukum Creek.


Water Shed Image The Newaukum Creek watershed is located in South King County in Water Resource Inventory 9 (WRIA 9) and drains an area of approximately 27.8 square miles (Kerwin and Nelson 2000). The creek originates in the mountains east of Enumclaw Plateau, flows for roughly 14 miles, and enters the Middle Green River at River Mile 40.7. Eight tributaries to the creek provide and additional 13.5 miles of stream length.

Land use in the Newaukum Creek basin has gone from historic forested lands to agriculture and now to rural residential. The upland part of the basin (approximately 25 percent of the basin) was noted to consist primarily of commercial forest production in 2000 (Kerwin and Nelson 2000). This area is located outside the Urban Growth Boundary (UGB) and will likely remain in commercial forest production. The mid-section of the creek is known as the Enumclaw Plateau and consists of agriculture (pasture), low-density residential, and low-to-high density residential and commercial land uses. The Enumclaw Plateau area occupies approximately 57 percent of the basin.

For more information about the Newaukum Creek watershed, visit the WRIA 9 website for the Middle Green River Subwatershed.


Chinook, coho, sockeye, and chum salmon as well as winter steelhead have been observed spawning in Newaukum Creek (Kerwin and Nelson, 2000). Resident and Anadromous cutthroat have been observed throughout the basin. This subbasin of the Green-Duwamish watershed is considered to be a major producer of winter steelhead, coho and chinook salmon. The Newaukum Creek Basin Characterization Project Report provides more detailed information about habitat conditions in the Newaukum Creek area.

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

Water quality conditions in Newaukum Creek have historically been characterized as “fair” (Metro 1989) due to high nutrient concentrations and high fecal coliform bacteria counts related to agricultural practices.

Long-term Trends

A 25-year (1979 – 2004) trend analysis was conducted with baseflow water quality data collected from the mouth of Newaukum Creek. This analysis shows that there have been some improvements in water quality since 1979. Total suspended solids, ammonia, total nitrogen, and fecal coliform bacteria have all shown a significant decrease in this 25-year time period. pH values have shown a significant decreasing trend. However, conductivity and phosphorus concentrations (both ortho-phosphorus and total phosphorus) have increased significantly during this same time period and pH levels have lowered. In spite of improvements noted since 1979, a water quality data assessment conducted for the Green-Duwamish River in 2003 found that Newaukum Creek continues to have low dissolved oxygen and high nitrate-nitrogen, total nitrogen, ortho-phosphorus, total phosphorus concentrations in both base and storm flow, particularly at sites representing agricultural land use, relative to the rest of the Green-Duwamish watershed (Herrera 2005). Turbidity and total suspended solids were elevated in the creek during storm events. Total aluminum concentrations exceeded U.S. EPA chronic criterion during base flow sampling, and acute criterion during storm flow sampling.

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 Newaukum Creek ratings compare with other stream sites, visit the WQI page.

Table 1. Routine monitoring summary statistics for this station from 1972 to 2018
ParameterNumber of SamplesMeanMinimumMaxmiumMedianStandard Deviation
Dissolved Oxygen (mg/L)24811.29.014.311.01.0
Temperature (°C)3849.70.516.89.83.5
Turbidity (NTU)3603.960.40333.001.9817.82
Conductivity (mSIEMS/cm)219143.972.4171.0146.015.0
Total Suspended Solids (mg/L)3978.280.00986.003.4050.42
Ortho-Phosphorus (mg/L)3980.07160.00500.61400.04730.0643
Total Phosphorus (mg/L)3980.10930.01670.91700.07430.0977
Ammonia (mg/L)3990.07790.00431.94000.02190.1719
Nitrate (mg/L)3981.88230.88004.20001.76000.5337
Total Nitrogen (mg/L)3122.26550.21405.31002.12500.7134
Fecal Coliform(CFU/100ML)394587514000851642

Table 2. Storm water monitoring summary statistics for this station from 1972 to 2018
ParameterNumber of SamplesMeanMinimumMaxmiumMedianStandard Deviation
Dissolved Oxygen (mg/L)4511.19.412.811.10.9
Temperature (°C)699.
Turbidity (NTU)11415.450.80213.008.9424.04
Conductivity (mSIEMS/cm)34132.389.0163.0132.020.0
Total Suspended Solids (mg/L)9430.301.10504.0014.1061.52
Ortho-Phosphorus (mg/L)1220.15610.02080.42300.13450.1026
Total Phosphorus (mg/L)1220.25750.03360.85200.22550.1630
Ammonia (mg/L)1220.10070.00790.60000.06920.1053
Nitrate (mg/L)1222.03420.98804.55001.93000.6275
Total Nitrogen (mg/L)1193.01300.68206.25002.86000.9370
Fecal Coliform(CFU/100ML)1213528105400017006572


King County maintains ten water temperature gauges on Newaukum Creek at 305th Ave SE (44H), 212 Ave SE (GRT09), SE 424th St (GRT11), 292nd Ave SE bridge (GRT12), Newaukum Cr @ SE 416th (GRT24), Spring Creek (GRT25), Newaukum Cr @ SE 244th (GRT26), Newaukum Cr @ SE 248th (GRT27), North Fork Newaukum @ 292nd Ave (GRT28), and Newaukum Cr @ SE 416th & 278th (GRT29)

Stream Sediment

Sediment data were collected from Newaukum Creek as part of the Stream Sediment Monitoring Program from 1987 through 2002. Data analysis identified no significant trends for any of the parameters tested. Basin-wide sampling occurred in 2009, including ten sites along the Newaukum Creek reach. Results indicate that Newaukum Creek sediments did not exceed any sediment quality guidelines.

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 Nuwaukum 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. Newaukum Creek is included in this analysis. More information about the GDWQA, as well as the reports, can be found at GDWQA page.