Surface Water Management

Snohomish County Drainage Manual

The current Snohomish County Drainage Manual is based largely on the Washington State Department of Ecology's 1992 Ecology Stormwater Management Manual for the Puget Sound Basin. This manual was adopted in 1998 by Snohomish County with an addendum. Since that time, several additional amendments have been adopted by Snohomish County. 

The documents listed below compose the entire Snohomish County Drainage Manual. The Drainage Manual is used in concert with Snohomish County code and Snohomish County Engineering Design and Development Standards. Snohomish County anticipates adoption of a revised Drainage Manual in 2010.

Drainage Manual Intro (pdf)

Volume I - Minimum Technical Requirements

Volume I of the 1992 Ecology Stormwater Management Manual for the Puget Sound Basin was adopted by Snohomish County in 1998. The 1998 Snohomish County addendum applies to this Volume.

• Chapter I - Intro and Table of Contents 
• Chapter I - Page 1 through 10 
• Chapter II - Intro through Page 7
• Chapter II - Page 8 though 17
• Chapter II - Appendices
• Chapter III
• Chapter IV - Intro through Page 5
• Chapter IV - Page 6 through 10
• Chapter IV - Page 11 through 21
• Chapter IV - Glossary, Part 1
• Chapter IV - Glossary, Part 2
• Chapter IV - Glossary, Part 3
• Chapter IV - Glossary, Part 4
• 1998 Snohomish County Addendum to 1992 Ecology Stormwater Manual
  • Page 1 through 19
  • Page 20 through 29
  • Page 30 through 38
  • Page 39 through 44
  • Page 45 through 49 
  • Page 50 through 56

Volume II - Construction Stormwater Pollution Prevention

Volume II of the 2005 Ecology Stormwater Management Manual for Western Washington was adopted by Snohomish County in 2005. The 1998 Snohomish County addendum does not apply to this Volume.

• Volume II

Volume III - Runoff Control 

Volume III of the 1992 Ecology Stormwater Management Manual for the Puget Sound Basin was adopted by Snohomish County in 1998. The 1998 Snohomish County addendum (see above) and the 2008 amendment related to facility maintenance (see below) apply to this Volume.

• Chapter I - Table of Contents through Page 21
• Chapter I - Page 22 through 33
• Chapter I - Page 34 through 52
• Chapter II - Table of Contents through Page 19
• Chapter II - Page 20 through 50
• Chapter II - Page 51 through 69
• Chapter III - Table of Contents through Page 29
• Chapter III - Page 30 through 60
• Chapter III - Page 61 through 91
• Chapter IV - Table of Contents through 21
• Chapter IV - Page 22 through 32
• Chapter IV - Page 33 through 62
• Chapter V 
• Chapter VI, VII and VIII
• October 5, 2009 Snohomish County Addendum to Volume III - This amendment replaces the existing Chapter III-9 with revised drainage facility and catch basin maintenance standards.
  

2008 Snohomish County Drainage Manual Volume IV

This document was written by Snohomish County and adopted in 2008 to replace previous Volume IV. The 1998 Snohomish County addendum does not apply to this Volume.

• 2008 Snohomish County Drainage Volume IV 

2009 Snohomish County Drainage Manual Volume V

This volume contains only a reference to the drainage maintenance standards in Volume III Chapter III-9. When the Drainage Manual is fully revised in 2010, maintenance standards and other information will be moved to Volume V.

• 2009 Snohomish County Drainage Manual Volume V 

Contact

Please address any questions to: Bill Leif, (425) 388-3148 

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