Water Quality Monitoring

The City of Sammamish monitors water quality in streams, rivers and other water bodies. Monitoring is used to determine whether water bodies are meeting state water quality standards.

The City conducts a variety of water quality and flow monitoring activities of its natural resources and receiving waters. Monitoring is conducted for the purposes of:

1. Establishing baseline conditions to measure improvements,

2. Ensuring safe swimming beaches, and

3. Monitoring ecological changes.

The City conducted monitoring of Ebright Creek from 2015 to 2017. Activities increased in 2019 and continue today. Monitoring now includes Zackuse Creek, George Davis Creek, and the Allen Lake watershed. More information can be found in the Water Quality Monitoring Reports.

The City contracts with King County for monitoring services. These include hydrology gages which collect data on local creeks and rainfall.

Hydrology Data

Hydrology data includes rainfall and stream information. Several streams in Sammamish have gages that are monitored by King County. These gages collect streamflow and temperature. A map of their locations can be found on King County's Hydrology Data website.

Small Lakes Data

King County oversees a Small Lakes program and works with volunteers to collect water quality data throughout the County. Beaver and Pine Lakes are part of this effort. Volunteers collect samples and monitor water level, precipitation, temperature, and water clarity.

Water samples are collected between May and October. They are used to evaluate the health of the lake and the potential for algal blooms. Data analyzed includes phosphorus, nitrogen, chlorophyll, and other parameters. Sammamish provides monetary support to King County for this program.

Swimming Beaches

The City also monitors water quality at local swimming beaches in the summer. Monitoring is completed through an interlocal agreement with King County. Beaver Lake, Pine Lake, and Sammamish Landing beaches are all monitored for fecal coliform bacteria. Sampling happens approximately every other week during the summer months. If results exceed certain criteria, beaches are closed until water quality improves.

Stormwater Action Monitoring

The City does not have any streams or stormwater facilities included in the regional water quality monitoring program. The City contributes to Ecology’s Stormwater Action Monitoring (SAM) and participates in a municipal caucus related to the program. Contributions are made through its NPDES Phase II Permit. Information learned through this program can be helpful in advancing stormwater treatment in the region.