Managing stormwater from state highways

In spring 2019, the Washington State Department of Ecology issued us a Municipal Stormwater Permit (permit) that regulates stormwater runoff from our paved surfaces. The permit requires us to implement a Stormwater Management Program comprised of the program requirements listed in the permit.

Our Stormwater Management Program Plan (SWMPP) fulfills that obligation and describes how we will implement the 2019 permit’s requirements. The SWMPP is updated annually and submitted with the Stormwater Report.

Send feedback to the Stormwater Permit Program

We want to hear from you! Please provide feedback on the 2024 Stormwater Management Program Plan (SWMPP) (PDF 621KB). We will consider all comments received by October 1, 2025, before finalizing the 2025 plan.

Municipal Stormwater Permit Reports

Annual Stormwater Report

Read the 2024 Annual Stormwater Report (PDF 1.9MB) for an update on our compliance with the permit from July 1, 2023, to June 30, 2024 our reporting period. This document serves as the annual report required by the permit. Read the 2023 Annual Stormwater Report (PDF 1.5MB) to get an update on our compliance during the previous reporting period.

To request copies of Annual Stormwater Reports from previous years, contact Garrett Starks at Garrett.Starks@wsdot.wa.gov.

Annual Stormwater Monitoring Reports

In 2024 we submitted the Highway Monitoring Status Report Water Year 2023 (PDF 1.3MB) and Facility Monitoring Status Report Water Year 2023 (PDF 877KB). As required by Special Condition S7.D. of the permit, the reports summarize monitoring activities completed in Water Year 2023 (WY23) from October 1, 2022, through September 30, 2023.

In 2023 we submitted the Highway Monitoring Status Report Water Year 2022 (PDF 1.2MB) and Facility Monitoring Status Report Water Year 2022 (PDF 1.9MB). 

To request copies of Annual Stormwater Monitoring Reports from previous years, contact Brad Archbold at Brad.Archbold@wsdot.wa.gov.

Stormwater Retrofits

Stormwater Retrofit Management Plan (PDF 1.5MB) - Information about our Stormwater Retrofit Program and prioritizing retrofits.

Move Ahead Washington Stormwater Retrofit Legislative Reports

• 2023 Legislative Report
• 2024 Legislative Report

For stormwater retrofit guidance for project development, see the Stormwater & water quality webpage.

Construction Stormwater Permit Reports

Monthly Discharge Monitoring Reports (DMRs) – Use Ecology’s Permit and Reporting Information System (PARIS) to find submitted discharge monitoring reports.

Stormwater research

Stormwater research projects help identify state-of-the-art, cost-effective solutions for designing, constructing, and maintaining stormwater management systems. Visit our Research reports webpage to find information on past research. We are currently working on two stormwater research projects:

• Steep Slope Ksat Study – quantify runoff volume loss over roadway embankments as stormwater flows down the slope.
• CAVFS vs Compost Blanket over a VFS application for BMP runoff treatment effectiveness.

To comply with the permit, we also contribute funds to Stormwater Action Monitoring (SAM) for research related to the status and trends of water quality in receiving water bodies.

Quality assurance project plans (QAPPs)

A QAPP describes the objectives of a monitoring study and the procedures to follow to ensure the quality and integrity of collected data and ensure the results are representative, accurate and complete. To request copies of our stormwater monitoring QAPPs, contact Brad Archbold at Brad.Archbold@wsdot.wa.gov.

Standard operating procedures (SOPs)

SOPs describe procedures to follow for completing specific tasks. To request copies of our SOPs, email the contact related to the tasks below.

• Stormwater monitoring, contact Brad Archbold at Brad.Archbold@wsdot.wa.gov.
• Stormwater drainage system mapping, contact Cory Simon at Cory.Simon@wsdot.wa.gov.
• Data collection in TMDL areas, contact Elsa Pond at Elsa.Pond@wsdot.wa.gov.