Drainage Manual

Current Manual (Effective July 1, 2021)

Volumes I-VI below compose the entire Snohomish County Drainage Manual. The bioretention plant list from the 2012 LID Technical Guidance Manual for Puget Sound is incorporated by reference in Volume V. The Drainage Manual is used in concert with Snohomish County code and Snohomish County engineering design and development standards (EDDS).

• Volume I - Minimum Technical Requirements
• Volume II - Construction Stormwater Pollution prevention best management practices (BMPs)
• Volume III - Hydrologic Analysis and Flow Control BMPs
• Volume IV - Source Control BMPs
• Volume V - Runoff Control BMPs
• Volume VI - Stormwater Facility Maintenance
• 2012 LID Technical Guidance Manual for Puget Sound

Public Presentation - September 9, 2021 

Snohomish County Executive Office and county staff hosted a virtual public presentation about the public comments and the county's responses to them. The presentation is available to watch here.