Redmond Watersheds


A watershed is an area that drains rainfall and snowmelt to a specific creek, stream, river, or lake. Understanding conditions in a watershed is an extremely useful way of identifying actions that help restore streams.

Our Watersheds

The City has divided Redmond into 20 watersheds defined by how water drains off the land into our local streams. Our Watersheds Map (PDF) shows their locations.

Restoring and Protecting Redmond’s Watersheds

The City of Redmond Watershed Management Plan is an ambitious plan to improve the water quality and habitat conditions in all of Redmond’s streams over the next hundred years by studying and developing restoration plans for each watershed. 

Actions the City may take to restore watersheds include:

  • Retrofitting and creating new stormwater facilities.
  • Cleaning and maintaining our stormwater system and roads.
  • Sponsoring environmental education programs.
  • Restoring streams and streamside habitats.
  • Monitoring stream habitat and water quality.

Help protect our streams

Protecting our streams is a shared responsibility, and there are ways you can help!

  • Visit our "Keep Redmond Clean & Green" page for things you can do such as practicing natural yard care, washing your car at a car wash, picking up after your pet, and more! 
  • You can visit the Green Redmond Partnership page to join a habitat restoration work party.
  • Visit the Adopt-A-Drain!  page where you can “adopt” your very own stormwater catch basin to help prevent flooding and reduce pollution. 

Tosh Creek Watershed Street Sweeping Project

Street Sweeper in the FallStreet sweeping will occur on the first and third weekend of each month.

If you live in the Tosh Creek Watershed, please don’t park on the streets during the first and third weekends of each month. Please remember to check back here for any updates, as the dates may change depending on the weather.

Map of Tosh Creek Street Sweeping

With King County Wastewater Treatment Division funding, Redmond has launched increased street sweeping in the Tosh Creek Watershed. Tosh Creek Watershed is identified as a priority watershed within the Redmond Watershed Management Plan, which means Redmond will focus efforts to improve conditions in the watershed. Activities for this project include:

  • Street sweeping increased on the 3.54 miles of public roads within the Tosh Creek Watershed from quarterly to monthly  from October 2022 through September 2023.
  • Street sweeping within the Tosh Creek Watershed is increasing to twice monthly from October 2023 through September 2024.
  • Data will be analyzed to determine if increased street sweeping improved water quality within Tosh Creek.

The City uses water quality sampling from the Redmond Paired Watershed Study (RPWS) to determine if increased street sweeping, made possible by the King County WaterWorks grant, within the Tosh Creek Watershed will improve water quality.

The RPWS is designed to measure the effectiveness of actions taken by Redmond's Stormwater Utility and King County to restore urban streams on a watershed scale. This is done by analysis of monitoring data collected in six watersheds within Redmond, including the Tosh Creek Watershed.

This study in Tosh Creek will benefit the Puget Sound region by quantifying the benefits of street sweeping on in-stream water quality. Street sweeping is a cost-effective, readily available stormwater management tool that can be equitably served throughout a jurisdiction.

Do you live in the Tosh Creek Watershed? Please help this project by moving your cars off the street so more of the street can be swept!