Highway Runoff Manual

The Highway Runoff Manual (HRM) is an integral part of the obligations contained in the Washington State Department of Transportation’s (WSDOT’s) National Pollutant Discharge Elimination System (NPDES) municipal stormwater permit (permit). An Implementing Agreement with the Washington State Department of Ecology (Ecology) commits WSDOT to apply the manual statewide. All applicable WSDOT projects adding new impervious surfaces must use the HRM to design appropriate stormwater controls. The HRM directs 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 statewide. The HRM establishes minimum requirements and provides uniform technical criteria for: (1) Avoiding and mitigating impacts to water resources associated with the development of state-owned and -operated transportation infrastructure systems. (2) Reducing and minimizing water resource impacts associated with the redevelopment of those facilities. (3) Retrofitting existing facilities, both project-driven and stand-alone retrofit projects. The manual also provides guidelines for integrating the planning and design of stormwater-related project elements into the context of WSDOT project development process. This supplement is an update to the April 2014 HRM.


  • English

Media Info

  • Media Type: Digital/other
  • Edition: Supplement February 2016
  • Features: Appendices; Figures; Glossary; References; Tables;
  • Pagination: 526p

Subject/Index Terms

Filing Info

  • Accession Number: 01593935
  • Record Type: Publication
  • Report/Paper Numbers: M 31-16.04
  • Created Date: Mar 8 2016 11:09AM