Tualatin Basin Water Supply

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Scoggin Dam Studies Continue


In late July, the Bureau of Reclamation will resume investigations near Scoggins Dam. Crews will work on both sides of the dam as well as upstream and at other locations in the vicinity to collect soil and rock samples from up to 50 sites. Work will include drilling, construction of access roads, test pits, and other testing to assess dam safety and future water supply needs.

Work is scheduled to start after July 25, 2017, and is expected to continue through mid-December.



Although no road closures are anticipated, the testing may require temporary delays to move equipment to work areas. During investigations, crews expect minimal noise impacts and no harm to species, surrounding wetlands, or historic properties. The public is asked to stay clear of drilling equipment.



The Tualatin Basin Water Supply Project Partners have been working with the U.S. Bureau of Reclamation for more than 15 years to develop a new water supply for Washington County. Initially, the goal was to raise Scoggins Dam and enlarge the lake to meet the region’s long-term water needs. However, in 2010, Reclamation’s safety evaluation found that the dam—though safe and operating as designed—required significant seismic modifications.


Reclamation and Clean Water Services are looking at dam design concepts for the current dam location and for a location about half a mile downstream of the Stimson Mill. The goal is to explore the most cost-effective approaches before making final decisions.

As investigations continue during summer and fall of 2017, Reclamation and Clean Water Services will continue to develop its plan to evaluate various design options over the coming three to four years. The project team will provide neighbors with up-to- date information about design options being considered to protect public safety, secure our region’s water supply and meet future needs.

Download a PDF version of this update here.

Tom VanderPlaat