High School Creek Watershed

A Watershed (External link) is an area that drains rainfall and snowmelt to a specific creek, stream, river, or lake. A 642-acre watershed in northeast Redmond drains to a stream we call High School Creek. More than 730 million gallons of rain fall onto this watershed each year, draining to that creek.

The City recently completed a Draft High School Creek Watershed Restoration Plan to protect people and the environment by:

• Addressing issues influencing the quality and quantity of water flowing to the creek.
• Manage potential flooding issues in the watershed.
• Encouraging people to take action to help protect the creek.
• Partnering with King County ensures our actions are consistent with the region's watershed restoration and other conservation efforts.

When building neighborhoods, we alter how rainfall flows to our streams. In forested conditions, the land soaks up and slowly releases water over time. Roads, roofs, and parking lots reduce the land's ability to soak up water, generating stormwater runoff. This runoff flows quickly to creeks during storms. As the water flows other roads and lawns it picks pollutants. If not managed properly, stormwater runoff can cause flooding, erosion, and other problems that harm the stream's biology.

Although High School Creek is a relatively healthy stream for a developed area, there are still impacts from development. With thoughtful planning, we can address some of the issues causing impacts and ensure its health in the future.

The City is gathering information about possible retrofits to publicly owned stormwater facilities in the High School Creek watershed. As part of this effort, the City is:

1. Analyzing previously collected water quality and stream flow monitoring data, and drainage reports developed by past construction projects.
2. Gathering new information by walking the creek, talking to people, and conducting geotechnical investigations.

This work will result in a High School Creek Stormwater Facility Retrofit plan that will identify and prioritize specific construction retrofit projects that will address drainage issues, improve water quality, and/or reduce the number of high-energy, erosive flows to the creek.

Work on this plan began in April 2025 and will be completed in December 2026. The Plan will be used to budget projects in the watershed. It will be combined with other actions such as enhanced maintenance, educational activities, and habitat restoration projects to complete a High School Creek Watershed Restoration Plan.