King County Agricultural Drainage Assistance Program for Maintenance of Agricultural Waterways
Notice of Action under the State Environmental Policy Act (SEPA)

This SEPA determination is related to maintenance of waterways draining agricultural fields in unincorporated King County in a manner to protect salmonids.  These maintenance projects may include removal of the accumulated sediment and noxious or invasive vegetation that encroaches into and chokes  waterways or field drain tiles, and may also include culvert replacement or beaver dam removal.

King County worked with regulatory agencies to develop best management practices (BMP’s) for waterway maintenance in unincorporated King County agriculture areas. The BMP's are provided as attachments 1 through 10 below and cover the time of year for the project, sediment and erosion control, fish removal from the construction area, and planting requirements. Application of BMP’s may depend on the type of watercourse and the likelihood of salmonids present during the project. Waterways are classified as artificial, modified, or natural channels based how they were created. The likelihood of salmonids being present is based on known fish presence and the quantity and quality of the water. Waterways within the Agricultural Production Districts (APD’s) have been classified and waterways outside the APD’s will be classified on a case-by-case basis.

SEPA documents are provided in Adobe Acrobat format. For help using this format, please see our software help page.

Download documents:

• Notice of Action (61Kb)
• Decision to Proceed (37 Kb)
• SEPA Determination of Non-Significance (DNS) (68 Kb)
• Environmental Checklist (170 Kb)
• Part D - Supplemental Sheet for Non-Project Actions (59 Kb)
• Attachment 1- Requirements for a Farm Landowner to Conduct a King County Streamlined Agricultural Drainage Maintenance Project (45 Kb)
• Attachment 2 - Which Waterways Are Omitted from the Streamlined Agricultural Drainage Assistance Program (74 Kb)
• Attachment 3 - Pre-Construction Vegetation Removal Best Management Practices (95 Kb)
• Attachment 4 - Removing and Relocating Fish from ADAP Project Sites (13 Kb)
• Attachment 5 - Construction Best Management Practices (96 Kb)
• Attachment 6 - Beavers and Agricultural Drainage (106 Kb)
• Attachment 7 - Culvert Replacement (51 Kb)
• Attachment 8 - Post-Construction Erosion Control Best Management Practices (87 Kb)
• Attachment 9 - Revegetation Best Management Practices (159 Kb)
• Attachment 10 - Additional Actions Related to the King County Agricultural Drainage Assistance Program (16 Kb)

For questions about the SEPA Determination of Non-significance for King County's Agricultural Drainage Assistance Program, please contact Brian Sleight, Supervising Engineer, King County Stormwater Services Section.