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King County Washington home

Stormwater and surface water management

Information and resources for stormwater and surface water management in King County.

Share feedback about stormwater plans

Review and comment on our plans for managing stormwater in King County with this public survey. This includes stormwater regulatory updates, facility design guidelines, pollution prevention practices, and annual reports:

  • Title 9 updates to meet regulatory requirements.
  • Surface Water Design Manual, which describes the technical requirements for stormwater facilities.
  • The 2021 Stormwater Pollution Prevention Manual updates, which describe best practices to manage stormwater on commercial, multi-family, and residential properties.
  • Stormwater Management Plan (SWMP) which outlines what actions were done in the previous year to manage stormwater.
  • Stormwater Management Action Plan (SMAP) which lays out what actions we plan for the coming year to manage stormwater.

Report a problem

Report a flooding, drainage, or water quality problem in unincorporated King County.

Stormwater services and information

Resources and technical guidance to help manage stormwater.

Surface Water Management fee

Information about the King County Surface Water Management fee, and the current rates and discounts.

Stormwater drainage problems and assistance

Information about assistance that is available to help drainage problems in King County.

Surface Water Design Manual

Requirements and standards for designing surface and stormwater management systems in King County to mitigate the impacts of new development and redevelopment on natural and existing man-made drainage systems.

Stormwater pollution and prevention

Resources for preventing pollution at your home and business.

Stormwater Management Program

Reports, documents, and resources for our Phase 1 Municipal Stormwater National Pollutant Discharge Elimination System (NPDES) Permit.

Capital Services Unit

Projects that protect public health, property, and natural resources from flooding, soil erosion, and drainage problems caused by flooding.

Stormwater glossary of terms

Definitions for words about managing stormwater.