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King County Water Quality Monitoring

King County monitors the ecological health of the Laughing Jacobs Creek basin in a variety of ways, including collecting and analyzing water quality samples. Water quality samples were collected from one station, A670, from 1987 to 1988. In 2014, sampling was continued at the same station. Station A670 is located upstream from the mouth of the creek where the stream crosses East Sammamish Parkway SE. Currently, sediment quality data are not collected from this site.

From time to time, additional studies have been conducted on Laughing Jacobs Creek. Click here for information about Special Studies.


Laughing Jacobs Creek basin is a tributary to Lake Sammamish. The upper portion of the basin is within the City of Sammamish, Washington and the lower portion is within the City of Issaquah, Washington. According to Kerwin (2001), the Creek is approximately 8 square miles (it should be noted, however, that this information is dated). Headwaters of the Creek flow from Laughing Jacobs Lake through the plateau and into the southeastern shore of Lake Sammamish. In the summer, discharge is generally 10 cubic feet per second (cfs) whereas in the winter flows can exceed 50 cfs (Kerwin, 2001). Streams within the Creek, however, are impacted by sediment runoff from developed areas nearby. Sediment transport has caused aggradation of downstream channels and localized flooding along East Lake Sammamish Parkway in the past (Kerwin, 2001).

Total land use in the Laughing Jacobs Creek subbasin is mostly developed and forest. A majority of development is low intensity and open space while forestland is mostly mixed forest. Land is not used for agriculture in the area and scrub, wetlands, and other (grassland and open water) account for less than 10% of total land use. See Table 1 below for more details on land use.

Table 1. Total land use in the basin


Laughing Jacobs Creek is known for having several salmonids: Chinook, coho, kokanee, and sockeye. Cutthroat and rainbow trout are also present (Kerwin, 2001). The Creek is utilized for spawning by coho, kokanee, and adult sockeye. Of the “only three consistent spawning populations of late-run Lake Sammamish kokanee”, the Creek contains one of those populations with the lower reach of the Creek serving as an important migration corridor (AMEC Earth & Environmental, p. 4). Adult sockeye have been observed spawning in small numbers in the Creek.

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. Laughing Jacobs Creek is now categorized as "Core Summer Salmonid Habitat" for aquatic life use and "Extraordinary Contact" for recreational use. As part of the updated water quality standards, portions of Laughing Jacobs Creek have been assigned an additional “Supplemental Spawning and Incubation Protection” temperature criteria of 16 °C. The Creek is on the Washington State Department of Ecology’s (Ecology) 303(d) list for violation of water temperature, bioassessment, DO, and FC bacteria standards (Category 5). These violations occur in the Cedar-Sammamish watershed.

p>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 2014 to 2022
Developed Forest Scrub Wetlands Other
Total 65% 28% <1% 4% >2%
ParameterNumber of SamplesMeanMinimumMaxmiumMedianStandard Deviation
Dissolved Oxygen (mg/L)9710.78.913.410.61.0
Temperature (°C)9710.03.215.910.13.1
Turbidity (NTU)965.051.3351.603.825.79
Conductivity (mSIEMS/cm)97166.781.1240.1173.044.2
Total Suspended Solids (mg/L)9611.181.10113.006.9516.45
Ortho-Phosphorus (mg/L)960.02180.00700.06610.02200.0092
Total Phosphorus (mg/L)960.05270.02470.19400.04720.0229
Ammonia (mg/L)960.01770.00280.10600.01520.0134
Nitrate (mg/L)960.78790.09071.61000.71650.3733
Total Nitrogen (mg/L)961.06640.49902.16000.95950.3349
Fecal Coliform(CFU/100ML)761211420046480


King County maintains one streamflow gage at Laughing Jacobs Creek: East Lake Sammamish Parkway (15c).

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). Benthic invertebrate samples have been collected annually from Laughing Jacobs Creek since 2002 (except in 2004).

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 Laughing Jacobs Creek, please visit the Puget Sound Stream Benthos webpage.

Special Studies

Lake Sammamish State Park Redevelopment and Restoration Concept Plan

Following the last major capital investment in the 1970s, the Lake Sammamish State park experienced declining conditions and visitation. As a result, different plans and projects were proposed to revitalize the area. Efforts culminated in this conceptual plan to guide park development and restoration. Of the recommendations, some improvements lie within the floodplains of Laughing Jacobs Creek.

Salmon and Steelhead Habitat Limiting Factors Report for the Cedar - Sammamish Basin

As part of efforts to aid salmonid recovery, the Washington Conservation Commission and the Water Resource Inventory Area (WRIA) 8 Technical Committee jointly developed this report in 2001. The purpose was to provide a snapshot of existing salmon species and human influenced habitat conditions that could affect salmon in WRIA 8.