Initial CSI basin planning, 1999-2003

South Lake Sammamish planning area

The South Sammamish Basin is located in central King County around the southern half of Lake Sammamish. Regional wastewater facilities in the basin collect flows from the Sammamish Plateau Water and Sewer District on the east side of Lake Sammamish, the City of Issaquah at the south end of the lake, and parts of the City of Bellevue to the west of Lake Sammamish.

The primary problem in this area is the more than 20,000 feet of large-diameter pipe that will reach capacity within this decade, in some cases causing storm-related surcharging and possible overflows, as well as operations and maintenance issues related to two aging county pump stations. This is also a high growth area.

Proposed improvements for this basin include conveyance upgrades, diversions, and projects to attenuate peak flows, such as storage and I/I control. Planning was completed in the South Sammamish Basin in 2002.

South Lake Sammamish Report, October 2003

• Cover, Master Table of Contents, Executive Summary (572 KB)
• Task 210: South Sammamish Basin Planning Summary (2.2 MB)
• Task 220: South Sammamish Basin Facilities Review (9.4 MB)
• Task 230: Characterization of South Sammamish Basin Existing Conditions (6.8 MB)
• Task 240: Wastewater Service Alternative Development (18.5 MB)
• Task 250: Refining Wastewater Service Alternatives (10.5 MB)
• Task 260: South Sammamish Basin Task Summary (2 MB)