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King County Water Quality Monitoring

The Water Resource Inventory Area (WRIA) 7 Routine Streams Monitoring Program was established in 2011 and consists of twelve sampling sites that are distributed throughout the Snoqualmie and Skykomish watersheds. Historically in King County, routine streams monitoring has been centered on WRIA 8 (Lake Washington/Cedar/Sammamish) and WRIA 9 (Green-Duwamish). However, in 2011 a Surface Water Management (SWM) fee increase allowed King County to expand its regular water quality monitoring efforts to include the King County portions of the WRIA 7 drainage. Objectives of this program are focused on quantifying long-term water quality trends to help inform the management of salmon recovery efforts, land use regulation, and to prepare for expected increases in climate variability.

King County collects monthly water quality samples on the Raging River at its confluence with the Snoqualmie River near the Zurflueh Boat Launch in the town of Fall City. King County is not currently conducting benthic macroinvertebrate or stream sediment monitoring in the WRIA 7 Routine Streams Monitoring Program.


Water Shed Image

The Raging River lies along the western edge of the Snoqualmie River. The Raging River generally flows in a northwesterly direction and joins the Snoqualmie River in Fall City, Washington, draining approximately 20,000 acres.

Land use in the Raging River sub-basin is primarily composed of forestry in the upper watershed, while low-density rural residential land use dominates the lower basin. The unincorporated towns of Preston and Fall City exhibit higher density residential areas as well as commercial and industrial uses. The Washington Department of Natural Resources owns and manages large blocks of forested lands in portions of the basin, including some areas classified as rural residential land-use under the King County Comprehensive Plan. Forested lands in the upper watershed are mostly under private ownership (Kaje, 2009). There is also a significant amount of scrub, but very little wetlands and other land uses (barren land, grassland, and open water) and no agriculture. See Table 1 below for more details on land use.

Table 1. Total land use in the basin

Developed Forest Scrub Wetlands Other
Total 7% 70% 18% <1% <5%


The Raging River is one of the core spawning areas for Snoqualmie Chinook salmon, as well as populations of steelhead and coho (Haring, 2002).

Water Quality

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 (FC) 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. The Raging River 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, the Raging River has been assigned an additional “Supplemental Spawning and Incubation Protection” temperature criteria of 13 ºC to be applied from September 15th to June 15th. A short reach of the Raging River near its mouth is listed on the Washington State Department of Ecology's (Ecology) 303(d) list as "waters of concern" (Category 2) for DO, though no major violations of have been observed on the Raging River. The river is also in violation of water temperature and pH standards (Category 5). There are two types of EPA-approved total maximum daily load (TMDL) plans in place and implemented: a Snoqualmie River Watershed Multiparameter TMDL for FC bacteria and temperature; and a Snoqualmie River Watershed Temperature TMDL (Category 4a).

See Table 2 below for routine monitoring summary statistics of water quality data collected to date. If stormwater data is available for this site, it will be shown as Table 3. Historical data reviews can be found in the annual reports produced by METRO/King County DNRP.

To view charts of current water quality data, please visit the Data Download webpage.

Water Quality Index

A Water Quality Index (WQI) rating system was developed by Ecology that evaluates several water quality parameters and gives a single rating of “high,” “moderate,” or “low” water quality concern. To see how Raging River ratings compare with other stream sites, please visit the Water Quality Index webpage.

Table 1. Routine monitoring summary statistics for this station from 2011 to 2023
ParameterNumber of SamplesMeanMinimumMaxmiumMedianStandard Deviation
Dissolved Oxygen (mg/L)15111.69.113.911.61.1
Temperature (°C)1519.62.419.58.94.6
Turbidity (NTU)1383.850.50113.001.2113.18
Conductivity (mSIEMS/cm)15156.025.1112.248.020.6
Total Suspended Solids (mg/L)1508.630.60356.001.9034.67
Ortho-Phosphorus (mg/L)1500.00340.00090.01180.00320.0016
Total Phosphorus (mg/L)1490.01480.00510.22700.00950.0271
Ammonia (mg/L)1500.00560.00200.02610.00420.0039
Nitrate (mg/L)1500.44180.03101.70000.39600.3185
Total Nitrogen (mg/L)1490.54170.08101.85000.46200.3360
Fecal Coliform(CFU/100ML)125681180021195


King County is not currently operating any stream, rain, or temperature gages on the Raging River. However the U.S. Geological Survey (USGS) does operate a stream gage on the Raging near the City of Fall City, Washington (12145500).

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 webpage.

While King County is not conducting benthic macroinvertebrate monitoring on the Raging River as part of the WRIA 7 Routine Streams Monitoring, limited benthic sampling has taken place in the Raging River drainage. To see this data, please visit the Puget Sound Stream Benthos webpage.