Since 1999, Clark County has had a National Pollutant Discharge Elimination System (NPDES) Phase I Municipal Stormwater Permit. The current Permit is effective August 1, 2024, through July 31, 2029. The Washington State Department of Ecology  issues NPDES Stormwater Permits as part of its responsibility to enforce the federal Clean Water Act in Washington State.  

This Stormwater Permit requires the County to implement regulations for managing the quantity and quality of stormwater discharged from the county’s stormwater system to our local creeks, streams, rivers and groundwater. 

To achieve this, the Clean Water division maintains the Clark County Stormwater Code and Manual that guides new development and redevelopment practices in our community. The purpose of the Manual is to minimize impacts of the built environment on our waterways and to protect groundwater, which is our drinking water source.  

Clean Water coordinates closely with Clark County Community Development and the Development Engineering Advisory Board (DEAB) to review and update the Manual every five years, as required by the Washington State Department of Ecology’s Phase I Municipal Stormwater Permit. Revisions to the Manual are reviewed and approved by Ecology to ensure the development regulations and standards in our local Code and Manual are equivalent to the Stormwater Management Manual for Western Washington. 

The Stormwater Manual is implemented by Clark County Community Development through the development engineering review and permitting process. 

Clark County created the Clark County Stormwater Manual in 2015. The current Clark County Stormwater Manual 2021 became effective July 1, 2021. The manual is reviewed and approved by the Department of Ecology to ensure the local Code and Manual is equivalent to the Stormwater Management Manual for Western Washington. 

The Washington Department of Ecology found the 2021 Clark County Stormwater Manual equivalent to the 2019 Ecology Stormwater Management Manual for Western Washington, making it suitable for use by any western Washington municipality to meet state stormwater management requirements for development projects.