Earlier this week, the Army Corps of Engineers conducted its periodic inspection of Green Peter and Foster dams in the Willamette Valley.
The inspections, which occur every five years in order to identify any potential future problems, are the most thorough set of reviews conducted by the Corps. They also do an annual inspection of all 13 dams in the valley.
In the case of both dams, this week's inspections revealed nothing out of the ordinary, according to Ross Hiner, the Portland District’s Dam Safety program manager.
“It’s a time to look at what has changed over a five year period,” Hiner said. “For instance, the spillway gates at Green Peter have been rehabilitated over that time… As we go through these inspections together, we’re kind of putting pieces together of how the dams perform over time.”
In addition to its periodic inspections, the Corps performs risk assessments that aim to identify three components of risk: Hazards, consequences and performance.
“For Green Peter, we consider the risk to be relatively low,” Hiner said. “Our dams in the Willamette Valley are generally high-risk projects because… there’s potential for consequences. So we’re assessing the dams for very extreme scenarios like floods and earthquakes.”
Green Peter Dam is a concrete gravity dam that was built in 1967 and impounds the Middle Santiam River. Seven miles down the river is Foster Dam, which is a rock-fill structure that was created in 1968.
In 2014, Green Peter closed for a period of time so the Corps could make repairs and upgrades to one of the dam's spillway gates. Earlier this month, Corps officials said the water levels are up at Foster, Green Peter and nearby Detroit Reservoir, despite a dry start to the year.
Get local news delivered to your inbox!
Subscribe to our Daily Headlines newsletter.