Highway Runoff Manual

The Highway Runoff Manual (HRM) was developed to direct the planning and design of stormwater management facilities for new and redeveloped Washington State highways, rest areas, park-and-ride lots, ferry terminals, and highway maintenance facilities throughout the state. The Washington State Department of Transportation (WSDOT) manages its stormwater discharges to protect water quality, beneficial uses of the state’s waters, and the aquatic environment in general.
Architecture & Planning