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King County Water Quality Monitoring

King County monitors the ecological health of the Ames Creek basin in a variety of ways including collecting and analyzing water quality samples. Water quality samples have been collected monthly at since 2011 from one station in Ames Creek. Station Ames_1 is located near the mouth of the creek on the upstream side of NE 100th Street, just east of West Snoqualmie Road.

Ames Creek is part of the Snoqualmie River Basin in Watershed Resource Inventory Area 7 (WRIA 7). WRIA 7 consists of two major drainages on the west side of the Cascade Mountains, the Snoqualmie and the Skykomish Rivers. Together, these rivers comprise the Snohomish drainage that empties into Puget Sound near the city of Everett, Washington. For more information about the Snoqualmie Watershed check out the Snoqualmie Watershed Water Quality Synthesis Report.


Water Shed Image

The upper reach of the Ames Creek basin is fairly steep before entering Ames Lake (Kaje 2009).The lake is 76 acres ringed with homes on lots ranging from one third to over one acre in size. The creek continues at the outlet on the north end of the lake and descends to the Snoqualmie Valley floor, entering the Snoqualmie River at River Mile 17.5. Sikes Lake Creek is the main tributary to Ames, draining the northeast portion of the basin and Sikes Lake before joining the mainstem in the floodplain a short distance upstream from the creek mouth. Above the water quality station Ames_1, the creek drains approximately eight square miles.

Land use in the basin is roughly 70 % rural residential and 30% agriculture (Kaje 2009). The mainstem of the creek drains primarily rural residential uplands and then traverses the Agricultural Production District (APD) across the floodplain of the Snoqualmie. The majority of the APD within the Ames Creek basin is within the 100-year floodplain of the Snoqualmie and is prone to flooding when the river is running high. The lower floodplain portion of the creek has been deepened and straightened over the years to benefit agriculture along the valley floor. The upland areas also have experienced substantial encroachment of residential and agricultural development into riparian areas, loss of functional wetlands and mature forest. The need to protect and restore hydrologic and sediment processes in the Ames Creek sub-basin was highlighted in the Snohomish River Basin Salmon Conservation Plan (Snohomish Basin Salmon Recovery Forum 2005).


The Ames Creek basin is known to have the following salmonids: Chinook, coho, and steelhead (Kaje 2009). Chinook juveniles rear in the lower portions of the creek. Coho are known to ascend up to Ames Lake and beyond for spawning and rearing. Steelhead use is believed to be less extensive than coho salmon but more extensive than Chinook.

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. Ames Creek is now categorized as "Spawning, Rearing, and Migration" for aquatic life use and "Primary Contact" for recreational use. Several studies suggest that Ames Creek has poor water quality for several different parameters. The 2009 Snoqualmie Watershed Water Quality Synthesis Report provides an in-depth description of water quality data through 2009. High temperatures in the creek are a concern but state temperature standards are met most of the time. Nutrients are also of concern in the basin, particularly in the lower mainstem. Parameters reflecting ‘impaired’ conditions in the 2009 report are low dissolved oxygen, low pH, and high fecal coliform bacteria in the mainstem of the creek. WDOE (2008) estimated that fecal coliform would need to be reduced by 86% in the basin to meet standards. Ames Creek is on the Washington Department of Ecology’s (Ecology) 303(d) list, Category 5, for violation of pH standards. See Table 1 below for a summary of water quality statistics for Ames Creek. See Table 2 below 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 WQI ratings for other stream sites, visit the Water Quality Index page.

Table 1. Routine monitoring summary statistics for this station from 2011 to 2018
ParameterNumber of SamplesMeanMinimumMaxmiumMedianStandard Deviation
Dissolved Oxygen (mg/L)888.84.711.69.01.2
Temperature (°C)889.81.916.69.93.6
Turbidity (NTU)778.592.3846.405.578.38
Conductivity (mSIEMS/cm)88132.021.5176.0136.030.2
Total Suspended Solids (mg/L)8810.391.4080.007.9510.49
Ortho-Phosphorus (mg/L)880.04420.00680.20600.03940.0243
Total Phosphorus (mg/L)870.08950.03600.30100.08110.0382
Ammonia (mg/L)880.08180.00890.35900.06610.0659
Nitrate (mg/L)880.56900.21601.48000.51650.2307
Total Nitrogen (mg/L)871.09930.46902.30001.08000.4109
Fecal Coliform(CFU/100ML)882176180097347


King County maintains one streamflow and temperature gauge at Ames Lake Creek (01a).

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 Ames Creek, please visit the Puget Sound Benthos webpage.

Special Studies

1994 Snoqualmie River Total Maximum Daily Load (TMDL) Study (Joy 1994)

Due to concerns about water quality, the Washington State Department of Ecology (Ecology) conducted a study of the Snoqualmie River and tributaries during 1989-91. In 1994 Ecology made recommendations on how to protect and improve water quality in the river in this report. For more information, download a copy of the report.

2008 Snoqualmie River Basin Fecal Coliform Bacteria, Dissolved Oxygen, ammonia-Nitrogen, and pH Total Maximum Daily Load--- Water Quality Effectiveness Monitoring Report. (WDOE 2008)

During 2003-05, Ecology conducted this study to determine the effectiveness of cleanup efforts in the Snoqualmie River watershed. The study analyzes the effectiveness of 1994-2004 TMDL implementation activities in protecting and restoring water quality. Water quality in the Snoqualmie River has improved, but more effort is needed to ensure that Washington State water quality standards and TMDL targets are met. For more information, download a copy of the report.

2009 Snoqualmie Watershed Water Quality Synthesis Report. (Kaje 2009)

The Snoqualmie Watershed Forum is committed to protecting and enhancing the Snoqualmie River Watershed as an outstanding natural resource. This report synthesizes information about water quality in the watershed to inform the Forum and partner organizations bout its condition on the sub-basin level. The report identifies priorities for on-the-ground actions as well as key data gaps that should be addressed through monitoring or targeted studies. For more information, download a copy of the report.