Sewer System Plan

The City of Issaquah Sewer System Plan (PDF) (and attachments (PDF)) serve as a guide for planning and designing future sewerage facilities.


Issaquah's sewer system is a conveyance system only and functions mostly by gravity flow. Wastewater is sent to King County Wastewater Division's Renton Wastewater Treatment Plant via a system of interceptors and pump stations that are also operated by King County.