Drainage Manual - Past Edition

Snohomish County Drainage Manual Effective from September 21, 1998 to July 1, 2006

Snohomish County Drainage Manual Effective from July 1, 2006 to August 18, 2008

Snohomish County Drainage Manual Effective from August 18, 2008 to October 19, 2009

Snohomish County Drainage Manual Effective from October 19, 2009 to September 30, 2010

Snohomish County Drainage Manual Effective from October 1, 2010 to January 22, 2016