Applications & Fees
Septic Program
Updates to Lewis County Code 8.40, On-Site Sewage Systems
LCC 8.40, 2025
On August 26, 2025, the Lewis County Board of County Commissioners approved an updated Lewis County Code 8.40, On-Site Sewage Systems. Please see the attached document for the updated code. While the new code has not been published as of yet, it is effective as of August 26, 2025.
To request a septic system construction final inspection, please call the Septic Inspection line at (360) 740-1330.
Onsite Septic Homeowners Handout
The On-site Sewage Program is responsible for evaluating site conditions for onsite septic systems, characteristics of soil in test pits, setting permitting conditions, and issuing permits for septic systems. On-site Program staff review and comment on land development projects and activities such as Subdivisions, Special Use Permits, Boundary Line Adjustments, SEPA documents, and other planning processes proposing on-site wastewater treatment and disposal.
We follow regulatory mandates and guidance documents from the State Legislature, Washington State Department of Health, the Environmental Protection Agency (EPA), and Lewis County Codes.
To learn more about how a Septic System works, please see Land Use Fact Sheet #2