Tualatin Basin Water Supply

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Doing nothing is not an option

Completed in 1975, Scoggins Dam is a generational investment, designed to serve our community for a century or more. In the process of studying an expansion of Hagg Lake to meet the region’s long-range water needs, it became clear the region must also plan for major earthquakes. New information on the Cascadia Subduction Zone off the Pacific Northwest coast predicts a large earthquake, threatening Scoggins Dam, Hagg Lake and infrastructure throughout the Northwest. 

The safety improvements to Scoggins Dam are critical to securing the region’s primary water supply and protecting the public.  The region’s future plans are predicated on the continued delivery of safe, secure and reliable water from Hagg Lake.  Scoggins Dam must be modified to reduce the risk of failure in a major earthquake in order to: 

  • Protect public safety
  • Help assure the public health and economic vitality of Washington County by securing the County's primary water supply
  • Help meet the future water needs of the region

Frequently Asked Questions

>To eliminate the earthquake risk, why not drain Hagg Lake or remove Scoggins Dam?
In our region 400,000 residents, 250,000 jobs and 17,000 acres of agriculture rely on the water stored in Hagg Lake. It is the water source for homes, farms and businesses throughout the Tualatin Valley, and currently the only source of water for City of Hillsboro. Life-giving releases from Hagg Lake keep the Tualatin River flowing in the dry months, and Hagg Lake is a thriving recreational asset.
>How do we know the Stimson Mill site, which could be contaminated, is a safe place to put a drinking water facility?
Public safety is the #1 goal of this project. The site will be thoroughly investigated if it is advanced for consideration as a preferred alternative. If the downstream dam option is selected and the mill is relocated, any contamination would be removed or remediated to meet increasingly stringent regulations for safe water.
>How can neighbors downstream of Scoggins Dam prepare for a major earthquake and the potential for the dam to fail?
All residents in the Pacific Northwest should be preparing for a major earthquake, especially those who live downstream of a dam. Precautions include having a 72-hour emergency kit, a family escape plan, and getting to know your neighbors to understand available resources and special circumstances that might exist nearby. In the event of an earthquake, anyone near the dam should head for the highest ground immediately. The Office of Emergency Management has information to prepare for an emergency at http://www.ocem.org/