2013 Water System Plan, Volume II - Seattle City Clerk's Office - City ...

5.2 GENERAL INFORMATION
SPU water facilities supply water to more than 1.3 million people in the Seattle area, including
wholesale customers (purveyors). The Tolt and Cedar watersheds supply most of the drinking
water. The Seattle well fields serve as a supplemental water source during droughts and
emergencies. Large transmission pipelines deliver water to treatment plants, and from the
plants to in-town storage facilities such as tanks and reservoirs. Smaller water pipelines
distribute water from in-town storage facilities to the public. Valves control water and isolate
sections in the distribution mains, which are monitored by Supervisory Control and Data
Acquisition (SCADA). Water services and fire hydrants are connected to distribution mains.
Purveyors are connected to transmission mains.
In the SPU system, most water flows via gravity from the watersheds to storage facilities in
Seattle. Storage facilities are set at high elevations to supply water via gravity to customers.
Where necessary, pumps are used to lift water to higher elevation storage facilities or to
increase water pressure. The system is managed by SPU Facility Operations and Maintenance
and monitored through SCADA.
5.2.1 Policy
The guiding policy document for water infrastructure is the SPU 2007 Water System Plan. See
Chapter 4 of the plan for SPU policy on water transmission. See Chapter 5 of the plan for SPU
policy on water distribution.
5.2.2 System Maps
SPU’s water maps are available at the following locations:
Base Maps
Customer Service Water GIS (software program). Contact SPU IT Service Desk
Printed 400’ Water System Map books
SPU GIS Mapping Counter (SMT 47 th floor)
5-4 SPU Design Standards and Guidelines