Water System Plan

Issaquah's Water System Plan (PDF) provides the City with a guide to evaluate the impacts of future proposed development and land use on the water system.


The City's water transmission and distribution system serves residents in and around the City of Issaquah within a water service area of approximately 10 square miles.

The system includes:

  • Approximately 120 miles of pipe ranging in size from four to 16 inches in diameter
  • 22 reservoirs on 13 sites totaling 13.7 million gallons
  • 14 booster pump stations
  • 32 pressure-reducing stations
  • Four production wells

All of the City's water storage facilities are covered, ground-level reservoirs or standpipes; there are no elevated tanks in the system.

Cascade Water Alliance

The City is a member of the Cascade Water Alliance (CWA), a group of seven cities and districts representing more than 50 percent of retail water sales in the region outside Seattle.

CWA's objective is to provide water supply to its members to meet current and future regional needs in a cost-effective and environmentally responsible manner.