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.
Highway Runoff Manual memorandums
Highway Runoff Manual memorandums are issued as interim updates to the Highway Runoff Manual.
Roles & Responsibilities for Stormwater Connection Utility Permitting During Project Delivery (PDF 790KB)
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.
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.