Low Impact Development in Clark County:
- State of Washington LID Trainings (2015)
- Department of Ecology - LID maintenance and operations - Training Videos (YouTube)
- EPA's webinar series on green infrastructure
Stormwater Code and Manual
Clark County has a National Pollution Discharge Elimination System (NPDES) Phase I Municipal Stormwater permit effective August 1, 2013 through July 31, 2018. The Washington Department of Ecology permit is part of the federal Clean Water Act. Clark County has operated under such a permit since 1999.
This permit, among other things, specifies regulations for managing the quantity and quality of stormwater discharged from the county’s stormwater system to our local creeks, streams, rivers and groundwater.
Clark County most recently updated code and manuals in 2015. The update was a two-year effort and included numerous stakeholders. The current 2015 Clark County Stormwater Manual became effective January 8, 2016. The manual has been reviewed and approved by the Department of Ecology and is considered equivalent to the 2014 Stormwater Management Manual for Western Washington.
Clark County utilizes municipal code to set regulations for local land use, development and best management practices to minimize pollution and disturbances to stormwater in our community. Specific codes for stormwater include:
- 13.26A Water Quality - sets regulations for how to protect water quality
- 40.386 Stormwater and Erosion Control - sets regulations for development related to protection of stormwater
- Title 40 - Numerous Sections of code reference development practices, including the use of Low Impact Development and requirements to minimize impacts to stormwater, including landscaping, parking, and building sections
Clark County Stormwater Manual 2015
The stormwater manual is a comprehensive document to guide project applicants and developers through every step related to stormwater planning, design, construction, maintenance and operation. The manual is divided into four books directed to various users.
Note: All books include hyperlinks to references and cross-referencing for ease of use. To ensure cross-referencing works, download .pdf files into the same file folder and maintain existing file names.
- Clark County Stormwater Manual (CCSM) - Introduction
- CCSM Book 1 - Applicability, BMP Section and Submittals
- CCSM Book 2 - BMP Design
- CCSM Book 3 - Source Control
- CCSM Book 4 - Maintenance and Operations
- Appendix 1-I - Site Plan Short Form - This link is for small project developments, such as single-family residential
- Appendix 1-J - Abbreviated Construction Stormwater Pollution Prevention Plan (SWPPP)
- LID stormwater feature signage (.pdf's)
- Entire Stormwater Manual (all eight files above) - .ZIP file (68 MB)
- Errata Sheet for the Clark County Stormwater Manaul 2015 (to be developed)
Western Washington Hydrologic Model
Update (December 2015) - Clark County has worked with stakeholders and the Department of Ecology (DOE) to update the Western Washington Hydrology Model (WWHM) to more closely match conditions in Clark County. In 2010, Ecology conditionally approved this model and made it available for use. In June 2014, Ecology subsequently determined that the model approval conditions were not met and the WWHM was reverted to the default parameters.
On December 10, 2015 DOE granted approval for the use of the original locally-calibrated model from 2010 for four of the five soil groups, SG1, SG2, SG4 and SG5. The model is now allowed for use on projects having these soil types.
DOE required one change to the SG3 soil group before it can be used. That change is being made now and should be available by the the end of January 2016.
If you have questions please call Jeff Schnabel at 360-397-2121 x4583.
- Clark County WWHM Soils Groupings - 2010 Soils Report
- Washington State Department of Transportation - 2016 Highway Runoff Manual
- Washington State Hydrologic Model - WWHM2012 version
U.S. Environmental Protection Agency - Low Impact Development "Barrier Busters" fact sheets
Visit our Low Impact Development web page for information about trainings related to stormwater planning, design, maintenance and operations. More >>
- Adopting ordinance 2015-11-24 (adopted code and manual updates for 2016)
- Summary of code changes effective January 7, 2016
- Clark County Stormwater Manual (November 2009) (repealed 1-7-16)
- Appendix A 2009
- Appendix B 2009
- Appendix C 2009
- Appendix D 2009
- Clark County Municipal Code 40.385 (repealed 1-7-16) Stormwater and Erosion Control