Drainage Inventory Interactive Map & Data

Welcome to Snohomish County’s drainage inventory maps. This set of map enables citizens to view the county’s storm water infrastructure online. The drainage infrastructure includes catch basins, drainage features, and a drainage network that shows where storm water flows.

Zip File

If you would like to download the drainage inventory in a geographic information system (GIS) format, the zip file is here.


The inventory zip file is comprehensive drainage inventory collected by Surface Water Management (SWM) and Road Maintenance. Includes data collected by the Drainage Needs Report Surface Water Management effort and ongoing efforts. This file also includes the field procedures used in collection of the inventory data in PDF format and the data dictionary.

ESRI file geodatabase have the following abbreviations for data type:

  • auxilary_pt (Auxilary Points)
  • catchbasin (Catch Basins)
  • closed_detention (Closed Detentions)
  • culvert (Culverts)
  • enclosed_pipe (Enclosed Pipes)
  • energy_dissipator (Energy Dissipators)
  • facility_access (Facility Access)
  • fence (Fences)
  • media_filter_structure (Media Filter Structures)
  • network_auxilary (Drainage Networks other than pipes, culverts and open channel)
  • open_channel (Open Channels)
  • overflow-control (Overflow Controls)
  • permeable_pavement (Permeable Pavements)
  • polyperimeter (Perimeter points to build polygonal drainage features)
  • pond (Ponds)
  • water_quality_feature (Water Quality Features)
  • xsection (Cross Sections)

All metadata is in HTML format.

Data Disclaimer

All maps, data, and information set forth herein (“Data”), are for illustrative purposes only and are not to be considered an official citation to, or representation of, the Snohomish County Code. Amendments and updates to the Data, together with other applicable County Code provisions, may apply which are not depicted herein. Snohomish County makes no representation or warranty concerning the content, accuracy, currency, completeness or quality of the Data contained herein and expressly disclaims any warranty of merchantability or fitness for any particular purpose. All persons accessing or otherwise using this Data assume all responsibility for use thereof and agree to hold Snohomish County harmless from and against any damages, loss, claim or liability arising out of any error, defect or omission contained within said Data. Washington State Law, Chapter 42.56 RCW, prohibits state and local agencies from providing access to lists of individuals intended for use for commercial purposes and, thus, no commercial use may be made of any Data comprising lists of individuals contained herein.