Hydraulics Manual

The Hydraulics Manual provides detailed information on hydrologic and hydraulic analysis related to highway design. This manual should be used in conjunction with the WSDOT Highway Runoff Manual and the WSDOT Design Manual, specifically Section 1210.

Individual Chapters

Contents (PDF 184KB)

Chapter 1 Design Policy (PDF 553KB)
Chapter 2 Hydrology (PDF 2.0MB)
Chapter 3 Culvert Design (PDF 9.4MB)
Chapter 4 Open Channel Flow (PDF 798KB)
Chapter 5 Drainage of Highway Pavements (PDF 693KB)
Chapter 6 Storm Sewer (PDF 573KB)
Chapter 7 Water Crossings (PDF 214KB)
Chapter 8 Pipe Classifications and Materials (PDF 541KB)
Chapter 9 Highway Rest Areas (PDF 13KB)
Chapter 10 Woody Material in the Riparian Zone (PDF 3.7MB)

Glossary and Sources (PDF 347KB)

Revision History

April 2025

• M 23-03.11 complete manual (PDF 13.4MB)
• M 23-03.11 revision package (PDF 13.4MB)

April 2024

• M 23-03.10 complete manual (PDF 13.4MB)
• M 23-03.10 revision package (PDF 13.4MB)

May 2023

• M 23-03.09 complete manual (PDF 13.4MB)
• M 23-03.09 revision package (PDF 13.4MB)

April 2022

• M 23-03.08 complete manual (PDF 13.4MB)
• M 23-03.08 revision package (PDF 13.4MB)

March 2022

• M 23-03.07 complete manual (PDF 19.2MB)
• M 23-03.07 revision package (PDF 19.2MB)

April 2019

• M 23-03.06 complete manual (PDF 12.9MB)
• M 23-03.06 revision package (PDF 12.9MB)

March 2017

• M 23-03.05 complete manual (PDF 17.1MB)
• M 23-03.05 revision package (PDF 4.1MB)

January 2015

• M 23-03.04 complete manual (PDF 12.8MB)
• M 23-03.04 revision package (PDF 1.9MB)

June 2010

• M 23-03.03 complete manual (PDF 12.8MB)
• M 23-03.03 revision package (PDF 1.9MB)

January 2010

• M 23-03.02 complete manual (PDF 11.4MB)
• M 23-03.02 revision package (PDF 0.7MB)

July 2008

• M 23-03.01 complete manual (PDF 10.9MB)
• M 23-03.01 revision package (PDF 1.1MB)