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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 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, which is just east of West Snoqualmie Road.

Ames Creek is part of the Snoqualmie River Basin in Water Resource Inventory Area (WRIA) 7. WRIA 7 consists of two major drainages on the west side of the Cascade Mountains, the Snoqualmie River, and the Skykomish River. 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, please visit the Snoqualmie Watershed Water Quality Synthesis Report.

From time to time, additional studies have been conducted on the Ames Creek. Click here for more information about Special Studies.


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 that range from one third to over one acre in size. The creek continues at the outlet on the north end of the lake, descends to the Snoqualmie Valley floor, and enters the Snoqualmie River at river mile (RM) 17.5. Sikes Lake Creek is the main tributary to Ames. It drains the northeast portion of the basin and Sikes Lake before joining the mainstem in the floodplain, which is a short distance upstream from the creek mouth. Above the station Ames_1, the creek drains approximately eight square miles.

Total land use in the basin is mostly forest, agriculture, and forest. Forestland is mostly mixed forest; and agricultural lands are used mainly for pasture/hay, though there are some cultivated crops. Low intensity and open space development are the most common for developed lands. Other land use consists of barren land, grassland, and open water. See Table 1 below for more details on land use.

Table 1. Total land use in the basin

Agriculture Developed Forest Scrub Wetlands Other
Total 22% 14% 50% 5% 1% 8%

The mainstem of the creek drains primarily rural residential uplands and then traverses the Agricultural Production District (APD) across the Snoqualmie floodplain. The majority of the APD in 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. This has resulted in 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 (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. Ames Creek is now categorized as "Spawning, Rearing and Migration Habitat" for aquatic life use and "Primary Contact" for recreational use. As part of the updated water quality standards, portions of Ames Creek have been assigned an additional “Supplemental Spawning and Incubation Protection” temperature criteria of 16 °C. 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 DO, low pH, and high FC bacteria in the mainstem of the creek. The Washington State Department of Ecology’s (Ecology) estimated that fecal coliform would need to be reduced by 86% in the basin to meet standards (2008). Ames Creek is on Ecology’s 303(d) list for violation of pH standards (Category 5). The creek has 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 DO; and a Snoqualmie River Watershed Temperature TMDL plan ( 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 WQI ratings for other stream sites, please visit the Water Quality Index webpage.

Table 1. Routine monitoring summary statistics for this station from 2011 to 2019
ParameterNumber of SamplesMeanMinimumMaxmiumMedianStandard Deviation
Dissolved Oxygen (mg/L)1038.94.711.69.01.2
Temperature (°C)1039.81.916.69.73.6
Turbidity (NTU)928.172.3846.405.457.76
Conductivity (mSIEMS/cm)103134.021.5176.0143.029.9
Total Suspended Solids (mg/L)1039.651.4080.006.809.91
Ortho-Phosphorus (mg/L)1020.04160.00680.20600.03660.0236
Total Phosphorus (mg/L)1020.08630.03600.30100.07820.0364
Ammonia (mg/L)1020.07790.00890.35900.06200.0629
Nitrate (mg/L)1020.55410.21601.48000.49250.2206
Total Nitrogen (mg/L)1021.07800.46902.30001.06000.3952
Fecal Coliform(CFU/100ML)1031972180090326


King County does not currently operate any gages on Ames Creek.

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. To see the benthic macroinvertebrate data for Ames Creek, please visit the Puget Sound Benthos webpage.

Special Studies

Lower Cherry Creek and Lower Ames Creek Watersheds Dissolved Oxygen Study

Dissolved oxygen (DO) concentrations have frequently failed to meet Washington State water quality standards in the Snoqualmie River flood plain Agricultural Production District (APD) reaches of Cherry and Ames Creeks. However, Cherry and Ames Creeks are not on the federal Clean Water Act Section 303(d) list for DO because the data were yet to be verified for the most recent 2008 water quality assessment.

This study was conducted in order to: (1) characterize DO concentrations, (2) identify possible mechanisms that influence DO, and (3) provide information about the possibility of low DO coinciding with high groundwater-to-surface-water ratios during late spring following long periods of soil saturation.

2009 Snoqualmie Watershed Water Quality Synthesis Report

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 about its condition on the sub-basin level. The report identifies priorities for on-the-ground actions. It also identifies key data gaps that should be addressed through monitoring or targeted studies.

Snoqualmie River Basin Fecal Coliform Bacteria, Dissolved Oxygen, Ammonia-Nitrogen, and pH Total Maximum Daily Load: Water Quality Effectiveness Monitoring Report

During 2003 - 2005, Ecology conducted a 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.

1994 Snoqualmie River Total Maximum Daily Load (TMDL) Study

Due to concerns about water quality, Ecology conducted a study of the Snoqualmie River and its tributaries during 1989 - 1991. In 1994, Ecology made recommendations on how to protect and improve water quality in the river in this report.