Highway Runoff Manual
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
Slow down – lives are on the line.
In 2022, speeding continued to be a top reason for work zone crashes.
Even one life lost is too many.
Each year about 670 people are killed nationally in highway work zones. In 2022, Washington had six fatal work zone crashes on state roads.
It's in EVERYONE’S best interest.
95% of people hurt in work zones are drivers, their passengers or passing pedestrians, not just our road crews.