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. 

Publication Date: 
Tuesday, May 16, 2006
Publication Number: 
M 31-16
Last modified: 
04/05/2019 - 14:35
Publication Version: 
M 31-16.05
Manual Manager: 
Alex Nguyen
WSDOT HQ Design Office, Highway Runoff Unit
Planning and design of stormwater management.

2019 Highway Runoff Manual Individual Chapters

Clean Version

Chapter 1 Introduction to the HRM (pdf 209 kb)

Chapter 2 Stormwater Planning and Design Integration (pdf 213 kb)

Chapter 3 Minimum Requirements (pdf 483 kb)

Chapter 4 Hydrological Analysis (pdf 529 kb)

Chapter 5 Stormwater Best Management Practices (pdf 13.1 mb)

Chapter 6 Temporary Erosion and Sediment Control (pdf 123 kb)

Appendix 2-A Engineering and Economic Feasibility Evaluation for Meeting the Highway Runoff Manual Minimum Requirements  (pdf 213 kb)

Appendix 4-A Web Links (pdf 137 kb)

Appendix 4-B TR-55 Curve Number Tables (pdf 222 kb)

Appendix 4-C Eastern Washington Design Storm Events Blank (pdf 37 kb)

Appendix 4-D Infiltration Testing and Design (pdf 1.6 mb)

Glossary (pdf 392 kb)


Highway Runoff Manual Revision History



Complete Manual


2016 February


PDF (19 MB)

PDF (2.5 MB)

2014 April

M 31-16.04

PDF (29 MB)

PDF (29 MB)

2011 November

M 31-16.03

PDF (6.4 MB)

PDF (0.4 MB)

2010 May

M 31-16.02

PDF (6.4 MB)

PDF (0.4 MB)

2008 June


PDF (0.4 MB)

2007 March

M 31-16.01

PDF (6.1 MB)

PDF (0.5 MB)

2006 October



PDF (0.6 MB)

2006 May



PDF (0.6 MB)

2004 March


PDF (16.1 MB)

PDF (16.9 MB)

1995 February


PDF (0.7 MB)