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Codes to Critical & Environmental Areas

Properties in certain zones, or mapped with regulated environmental areas have project-specific requirements - like how far from critical areas to build, size and design rules - in addition to building regulations. Below is a brief overview of those environmental rules. How they may affect your project, suggested next steps, and links to details. For the full list of county codes, go to All County Codes. Start with Find Out What You Can Do with a Property to check if regulated environments are mapped on a property.

Critical Areas & Regulated Environmental Areas

If protected areas listed in this section are on a property, you may need an environmental expert to inspect the property and write reports before you apply for a permit or start any project. Expert reports detail size, location and type of critical areas, an important first step in knowing where you can build. 

  • Critical Areas - Applies to properties with Parcel Data Sheet or County Map showing critical areas listed below. 
    • These land/water/hazard areas are critical areas
      • Groundwater Sensitive Areas - These areas drain into drinking water acquifers.
      • Frequently flooded areas - See Flood Areas section below. 
      • Landslide Hazards / Bluff (including Marine Bluffs) / Steep Slopes - See Geological Hazards link below. County does in-office review of your property and plan. As long as your project was designed by professionals to meet safety codes associated with these hazards, additional inspections or reports are usually not required. See Geological Hazards (link below).
      • Marine Riparian Area - See Shoreline Master Program section below.
      • Prairie Indicator Soils - These areas often have protected plant species. County Prairie Plant Inspection required (link below) but no expert report needed. 
      • Shorelines - see Shoreline Master Program section below.
      • Wetlands - Expert environmental reports required and may have to be done during the rainy season because some wetlands aren't visible in dry conditions. County's Critical Area Determination report may be a good starting point.
    • How it may affect a project  Where you site your project will be determined by where these areas are located on the property. Codes specify how far away development must be from hazardous and sensitive enviromental areas. When planning, think about the total area impacted by a project (house, driveway, yard, garden, septic, septic drain field, construction materials staging, etc.). Permit application will be processed to meet critical areas code, and also critical-area-specific setback and design requirements in building, construction, septic and other codes. If your project is in or too near one of these areas, mitigation may be required.
    • Suggested Next steps May need to hire environmental or geological experts to inspect the property and prepare a report detailing location, size and type of critical area. For a fee, the county can inspect the property to confirm if critical areas are there. This Critical Areas Determination (CAD) report doesn't detail size or type, but may help you decide if you need to hire experts (link to About CAD report below). 
    • Which applications or forms to use Fill out forms to order a CAD report if you choose (See About CAD report link below) For other permits, use the permit forms for what you want to build or do, which are on the Permit Forms page.
    • Link to code Thurston County Code Title 24: Critical Areas
    • Links to more county information About CAD Critical Areas Determination Report,  About Critical AreasPrairie Plant InspectionAbout Geological Hazards,  Conditional Site Approval 
  • Flood Areas - Applies to properties on County Map in Flood and Groundwater Hazard area, or on a FEMA flood map or identified as such by survey using county flood monuments or other survey or engineering tools, methods and reports.
    • These areas are flood areas - Special Flood Hazard Areas (the collective name in county code, for various flood and high groundwater ares/zones, groundwater sensitive areas, flood and groundwater hazards, etc.). 
    • How it may affect a project  Where you site your project (of even if you can build due to safety concerns) is determined by where these areas are located on the property in relation to mapped, marked or known flood areas/zones. Codes specify how far away development must be from Special Flood Hazard areas. Codes may also call out design criteria for construction and septic. Codes determine if/when you can build or rebuild after a flood.
    • Suggested Next steps Start by checking county records for a flood elevation certificate already on file for the property. Find instructions for looking up existng flood certification, and other details at  the Develpoment Regulations for Flood Hazard Areas page linked below.
    • Which applications or forms to use No special forms needed. Go to Permit Forms page to find forms for what you want to build or do, 
    • Links to codes section 14.38.050 of Thurston County Code Title 14,  Thurston County Code Title 14: Buildings & Construction,  Thurston County Code Title 24: Critical Areas,  Thurston County Code Title 19: Shoreline Master Program.
    • Links to more county information Development Regulations for Flood Hazard Areas.
  • Shoreline Master Program - Applies to properties on or near streams, rivers, lakes and Puget Sound & docks, decks, houses and other structures on, near or in water.
    • These are shoreline areas Marine Riparian Area, any property on, near or with a stream, lake, river, Puget Sound, fresh or salt water. Even if the stream is only visible in some seasons or conditions.
    • How it may affect a project Homes, other buildings, and septic systems must be a specific distance from shoreline. Docks, decks, shoreline erosion control measures must meet design criteria in code. Your permit will be processed under Shoreline Master Program code (link below) and your project will be subject to setbacks, building and septic design criteria and other regulations in Title 19, in addition to any other building, land use, environmental health or safety regulations in other codes that apply to your project.
    • Suggested Next step - 
    • Which applications or forms to use No special forms needed. Go to Permit Forms page to find forms for what you want to build or do,
    • Link to code Thurston County Code Title 19: Shoreline Master Program
    • Links to more county information About Shoreline Master Program 

Habitat Conservation Plan (HCP)

Properties mapped with the species habitat or areas listed below are in areas protected by the federal Endangered Species Act. The county has a federal permit to issue building and development permits in these areas if the project meets the county's HCP ordinance. Learn more about the Habitat Conservation Plan

  • These are HCP areas
    • Mazama pocket gopher habitat: Occupied & Near.
    • Mazama pocket gopher soils: More Preferred & Less Preferred.
    • Oregon spotted frog areas.
    • Oregon vesper sparrow areas.
    • Taylor's checkerspot butterfly areas.
  • How it may affect a project  If you're planning to add buildings, septic systems, well or any ground-disturbing project your whole project area (project envelope) must be developed using the required Best Management Practices- BMPs (Appendix C on page 220 in the HCP document PDF) which include reduce footprint, cluster, build up to the fullest possible extent. When planning, think about the total area impacted by a project (house, driveway, yard, garden, septic, septic drain field, construction materials staging, etc.). Where you site your project will be determined by where these areas are located on the property. The goal in siting a project is to avoid impacting the habitat, or to reduce the impact through use of HCP BMPs. Impacts must be mitigated, meaning the lost habitat must be replaced elsewhere throug conservation. You can control mitigation fees through avoidance and minimization of impact. Option: You may get required ESA-permission directly from US Fish & Wildlife Service instead of Thurston County. After you receive your federal permit, your project will need county permits, too.
  • Suggested Next Steps Check out the HCP BMPs and design or modify your project with them (link below).They are not optional. Next, prepare an HCP Site Drawing on the HCP Map to see how much habitat (if any) your project may impact. Then fill in the blanks of an HCP Mitigation Worksheet to estimate possible mitigation fees associated with your project. Do all of this before submitting your application packet.
  • Which applications or forms to use No special forms needed,although you will need to submit your HCP Site Drawing, downloaded drawing files & mitigation worksheet along with your application packet. Go to Permit Forms to find forms for what you want to build or do.
  • Link to code - Thurston County Code Title 17: Environment
  • Link to more county information: For Builders & Permit Applicants, HCP Map, HCP website, HCP Document- (PDF- scroll to Appendix C on page 220) 

Trees  & Converting Forest Land to Other Uses


If you're planning to cut down trees or log timber from a property you will need a class Class IV Forest Practice permit from Thurston County. Find details on the county's Trees & Forest Conversion webpage. You'll also need the permit if:
  • Treed forest land will be converted to ag use, pasture, housing, roads, stormwater ponds, etc.
  • The timber harvest removes 5,000 board feet or more from an ownership within a given year.
The Permit Conditions
The permit includes a six-year moratorium or restriction on development, but that may be avoided if you prepare a Conversion Option Harvest Plan, that is:
  • Approved by Thurston County government. 
  • Indicates the limits and types of harvest areas, road locations, and open space. 
  • Gets submitted to the Department of Natural Resources as part of the forest practice application.
  • Managed and followed by the landowner, maintains the landowner's option to convert to a use other than commercial forest product production (releases the landowner from the six-year moratorium on future development).
About Forest Practices Act & Permits
The Washington State Department of Natural Resources (DNR) administers the Forest Practices Act (RCW 76.09). However, Thurston County is responsible for permitting forestry activities noted above. The development moratorium is a restriction placed on a parcel as a result of logging conducted as a Class II, III, or certain Class IV Forest Practice permits issued by DNR, or for forest practices which were commenced without a Forest Practice permit from either DNR or Thurston County.  DNR is generally responsible for administering forest practices on larger parcels, and commercial forest lands which are to remain in active timber production and will not be converted to another use such as pasture, housing, etc. For more information about obtaining a Forest Practices Permit from DNR, please see DNR's Forest Practices web page. 


WEBSITE FOR INFORMATION ONLY. The descriptions, maps, links, and information on this website are for informational purposes only. Every property and project is unique. Maps may not accurately represent current ground conditions at a property now or at the time of application. Maps, regulatory descriptions, information, explanations suggested steps, etc. don't meet legal, engineering or survey standards. Consult with your own experts before making decisions.

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