Managing stormwater from state highways
Learn how we manage stormwater runoff from paved surfaces like highways, rest areas, park-and-ride lots, ferry terminals and maintenance facilities in urban areas throughout the state.
In spring 2019, the Washington State Department of Ecology issued us a Municipal Stormwater Permit (permit) to regulate stormwater runoff from our paved surfaces. The permit requires us to implement a Stormwater Management Program made up 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 2025 Stormwater Management Program Plan (SWMPP) (PDF 1.23MB). We will consider all comments received by October 1, 2026, before finalizing the 2026 plan.
Municipal Stormwater Permit Reports
Annual Stormwater Report
Read the 2025 Annual Stormwater Report (PDF 1.2MB) for an update on our compliance with the permit from July 1, 2024, to June 30, 2025 our reporting period. This document serves as the annual report required by the permit. Read the 2024 Annual Stormwater Report (PDF 1.2MB) 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 2025 we submitted the Final BMP Evaluation Report (PDF 3.2MB) and Facility Monitoring Status Report Water Year 2024 (PDF 1.2MB). As required by the permit, the final BMP evaluation report summarizes WSDOT's 2020-2024 biofiltration effectiveness longevity study, while the facility status monitoring report summarizes monitoring activities completed in Water Year 2024 (WY24) from October 1, 2023, through September 30, 2024.
In 2024 we submitted the Highway Monitoring Status Report Water Year 2023 (PDF 1.3MB) and Facility Monitoring Status Report Water Year 2023 (PDF 1.6MB).
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
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.
Slow down – lives are on the line.
Drive the posted speeds, they’re there for your safety.
Phone down, eyes up.
Pay attention – both to workers directing you and to surrounding traffic.
Stay calm
Expect delays, leave early or take an alternate route if possible; no appointment is worth risking someone’s life.