Highway Runoff Manual
Publication URL
Publication Number
M 31-16
Publication Version
M 31-16.05
Publication Date
Manual Manager
Alex Nguyen
Originator
WSDOT State Hydraulics Office, Stormwater Unit
Subject
Planning and design of stormwater management.
The Highway Runoff Manual (HRM) provides guidance to direct the planning and design of stormwater management facilities for existing and new Washington State highways, rest areas, park-and-ride lots, ferry terminals, and highway maintenance facilities throughout the state. The HRM establishes minimum requirements and provides uniform technical guidance.
Revision History
M 31-16.05 April 2019
Supplement February 2016
M 31-16.04 April 2014
M 31-16.03 November 2011
M 31-16.02 May 2010
June 2008
M 31-16.01 March 2007
2006 October
2006 May
2004 March
1995 February
166,800 electric vehicle
registrations in Washington in 2023, up from 114,600 in 2022.
87 wetland compensation sites
actively monitored on 918 acres in 2023.
25,000 safe animal crossings
in the Snoqualmie Pass East Project area since 2014.