Table of Contents
- Permit Process Overview (Including Septic)
- Pre-Application Meetings: When Are They Helpful?
- Steps in the Permit Application & Consultant’s Role
- How a Consultant Brings Flexibility and Efficiency
- References and Resources
Permit Process Overview (Including Septic)
When planning a new residential development in unincorporated Snohomish County, typical permits required include:
Building Permit for the structure.
Land Disturbing Activity (LDA) or Grading/Clearing Permit, required if your project disturbs soil or vegetation.
Your development must also go through critical area review, which may include a Critical Area Site Plan (CASP) if wetlands, streams, or geologic hazards lie within the building footprint or buffers.
If you’re on septic, the Snohomish County Health Department must approve septic system design, including drainfield placement. Wetland delineations and stream assessments by a qualified professional ensure these systems don’t encroach on critical areas—or support buffer mitigation if needed. This isn’t a separate permit; septic review happens concurrently with PDS review during intake. Residential Building Permit Handout
To check if your property may be subject to critical areas, use the PDS Parcel Map and toggle the critical areas layers in the PDS Map Portal—this helps determine if you’re within 400 feet of pertinent features. Snohomish County Critical Areas Mapper
Pre-Application Meetings: When Are They Helpful?
Requesting a Pre-Application Conference can be invaluable if your site:
Lies in a flood hazard zone, critical area, or has complex drainage or septic considerations.
Has unusual lot conditions, unclear boundaries, or previous development.
Involves buffer reductions or innovative mitigation (e.g., septic encroachment with buffer enhancement).
A pre-app lets you meet with PDS and Health Department staff, get clarity on documentation and process expectations early, and reduce delays during full submittal. Pre-Application Meeting Page
Steps in the Permit Application & Consultant’s Role
Preparation:
Confirm critical area proximity using PDS maps. If your project is within 500 feet of a mapped critical area, consulting is required.
Determine if your project triggers an LDA/clearing and if septic approval will intersect critical areas.
Consultant’s Critical Areas Review (Pre-Submission):
Before your application is even submitted to Snohomish County, it’s critical to have a qualified professional evaluate your site. Under SCC 30.62A.140, wetlands, streams, and fish and wildlife habitat conservation areas (FWHCAs) must be identified and mapped. This step is not optional — county reviewers cannot complete their job until you provide the technical reports and site plans that establish where buffers and setbacks exist.
Our team begins with a wetland delineation using the Corps of Engineers 1987 Manual and Regional Supplements, and conducts a stream/FWHCA assessment where appropriate. The outcome of this work is a site plan that overlays your proposed development footprint with buffer lines, setbacks, and septic system layouts, so you can see early in the process how your home, drainfield, and driveway relate to protected areas.
If the initial analysis shows conflicts — for example, a proposed drainfield overlapping with a wetland buffer — we prepare a Critical Areas Mitigation Plan. This may include strategies like buffer averaging, where wider areas of the buffer can be reduced in some spots if enhanced elsewhere, or buffer reduction with native plantings and enhancement to offset functional loss. These approaches provide flexibility and can allow septic systems or small building elements to encroach legally into otherwise restricted areas. By doing this work upfront, you avoid wasting months in back-and-forth with the County later.
Submit via PDS Permit Portal:
Once the technical documents are complete, the next step is uploading a complete permit package through the Snohomish County PDS Permit Portal. For new residential development, this typically includes:
The Building Permit application (for your dwelling or accessory structure)
An LDA (Land Disturbing Activity) permit if grading, clearing, or excavation is involved
A Critical Area Site Plan (CASP) showing buffers and protected features
Any Mitigation Plan developed by your consultant
Septic design documents reviewed by the Snohomish County Health Department
Consultant-prepared reports (wetland delineation, critical area study, FWHCA assessment, etc.)
Submitting a complete, consultant-prepared application ensures the County can move forward without rejecting your submittal for missing materials — a common cause of delays for applicants who skip hiring a qualified professional.
Intake & Review:
After submission, your application enters intake and review. Snohomish County PDS staff screen the documents to confirm they are complete. If something is missing or unclear, you may be asked to provide corrections or additional information.
During review, multiple departments are involved:
PDS Critical Areas staff evaluate your consultant’s reports, CASP, and mitigation plan.
The Health Department reviews your septic system design to ensure it avoids wetlands and streams, or that mitigation is provided if encroachment occurs.
A site reviewer may conduct a property visit to verify the accuracy of the delineation and the proposed development layout.
At the end of review, the County issues a Review Completion Letter outlining any required revisions. Having consultant-prepared studies up front greatly reduces the chance of major corrections at this stage, keeping your project on schedule.
Permit Issuance:
Once reviewers are satisfied and any revisions are addressed, your permits move toward issuance. At this stage you’ll:
Pay the required County permit fees.
Record the Critical Area Site Plan (CASP) and any mitigation documents with the County Auditor’s Office, making them a legal record tied to the parcel.
Receive your permit package, which includes the official permit, stamped plans, and inspection cards.
This milestone means you’ve cleared the environmental and health hurdles, and construction can legally begin.
Construction & Inspections:
During construction, it’s vital to follow the approved documents. Both County inspectors and Health Department inspectors will verify that your work matches the plans — whether it’s building setbacks, mitigation plantings, or septic installation. If buffer enhancement was part of your mitigation plan, inspectors will also confirm it was installed as designed.
After all inspections pass, you’ll receive final sign-off from the Health Department for septic and final approval from PDS for building and grading. At this point, your project is officially complete, with both development and environmental compliance fully satisfied.
How a Qualified Professional Brings Flexibility and Efficiency
Hiring a qualified wetland professional like Eastside Environmental Pros early in the process gives you:
Up-front clarity on what critical area regulations and septic constraints apply to your parcel.
Innovative solutions, like buffer averaging or buffer reduction with enhancement, to unlock viable septic placements.
Efficient coordination of septic, wetland, and critical area plans—ensuring all permit reviewers see consistent, higher-quality submittals.
Reduced back-and-forth, as we align your application with SCC 30.62A and anticipate Health Department needs before you submit.
References and Resources
Bulletin #23 – Residential Building Permit Process (for critical area, septic, pre-app): Building Permit Bulletin
Bulletin #15 – Critical Area Regulations for Residential Projects (wetland, buffers, mitigation): Critical Areas Web-Page
PDS Map Portal – Parcel and Critical Area Layers: Critical Areas Mapper
Ready to Move Forward?
Don’t navigate the permitting maze alone. Contact us via our Contact Us page, and we’ll help you assess your property, determine critical area requirements, and build your septic-friendly and buffer-compliant path forward—saving you time, cost, and stress.
