Seattle Public Utilities Mami Hara, General Manager/CEO

Seismic Planning

  • 30-inch water mai New earthquake-resistant 30-inch watermain on S Spokane St.
  • Cylinder on the base of Myrtle Tank Cylinder on the base of Myrtle Tank was installed to reduce earthquake vibrations.



Cygna Energy Services completed a comprehensive seismic vulnerability assessment of the Seattle Water Department’s facilities.

1990 – Today

We have been addressing the issues identified in the Cygna assessment, as well as planning for and incorporating modern seismic standards into new projects mandated by federal and state regulations.

Balancing priorities between seismic upgrades, regulatory-driven projects, and other capital needs while maintaining affordable rates has been an important element of the utility’s thinking—especially as we kept abreast of the evolving understanding of seismic risk in the Puget Sound region.


The Seattle Water Department merged with other city departments to form SPU.


SPU hired a recognized seismic expert to oversee our seismic planning.

2014 – 2017

SPU embarked on a new water system vulnerability study, scheduled for completion in 2017.

The study is evaluating how our water system might respond to two earthquake scenarios:

  • A magnitude 9.0 Cascadia subduction earthquake off the Washington coast
  • A magnitude 7.0 Seattle Fault earthquake centered in Seattle

2017 - 2018

SPU will be asking residents to provide their opinions about different seismic resiliency levels and cost. The goal is to learn what people are prepared to spend on seismic upgrades. This will help the utility identify funding sources and shape SPU’s strategic business plan.