Highlands Sewer Main Capacity and Redundancy Project

(Updated as of September 2021)

The following is a notable Capital Improvement Plan (CIP) development project located in Issaquah Highlands (subject to change and does not represent a budget commitment)

Highlands Sewer Main Capacity and Redundancy Project

Estimated completion 2023. The city will design and construct a redundant sewer main from Issaquah Highlands to the I-90 under-crossing to provide a redundant and larger capacity conveyance system that is safer and more reliable. Currently, one pipe conveys all sewage from Issaquah Highlands, running over a steep slope from 5th Avenue NE to the Issaquah Public Works Operations facility. The current system is more than 20 years old, designed when its planned use differed from its modern application. Today, the system experiences higher demands and higher flow than intended. Additionally, this system is the only sewer connection from Issaquah Highlands to the valley floor. A new redundant system would provide additional capacity and further protect critical facilities.