Water managers of Scoggins Dam making preparations in case of major earthquake
Posted September 8, 2017 1:58 p.m. EDT
WASHINGTON COUNTY, OR — Water managers in Washington County are facing a tough decision about the future of the Scoggins Dam, which holds back Hagg Lake.
Clean Water Services and the U.S. Bureau of Reclamation, the two entities who jointly manage and operate the dam and its downstream water releases, are weighing whether the dam can be retro-fitted to withstand a major earthquake, or whether it would be more feasible to build a new dam downstream.
According to Clean Water Services, initial investigations suggested the soil underneath the dam is vulnerable to a process called liquefaction, which means that in a major earthquake, the dirt could lose its shape and integrity, and stop supporting the dam that sits on top of it.
"In a case like this, the dam would probably slump, begin to slump, and then water would release," said Mark Jockers, a spokesman with Clean Water Services.
Currently, the U.S. Geological Survey is conducting exploratory drilling to determine the strength of the rock and soil beneath the dam.
If testing concludes shoring up the dam is unfeasible, building a new, modern dam downstream comes with its own challenges.
For instance, the entire area below the dam, which includes a 100-year-old sawmill and several homes, would be flooded.
Both the company and the homeowners would be offered fair market value for their properties.
"I'm OK with it either way. I think if they're going to build a dam, fix the dam, the sooner the better," said Andrew Walker, who recently bought a home below the dam.
A decision on a course of action is expected sometime in the next three years.