Idaho

Expert: "significant risk" of dam issues in east Idaho

Dam failure risk "significant" in...

IDAHO FALLS, Idaho (KIFI/KIDK) - The state of Idaho 's Dam Safety Program, run by the Idaho Department of Water Resources, is responsible for the inspection of nearly 450 dams across the state. Many of the dams across the Gem State are extremely old, which plays a factor into its stability.

"The older the dam, the more problems it experiences based on age,” Dam Safety Program Manager John Falk said.

The age of the dams holding back thousands of gallons of water in east Idaho is a concern for those responsible for making sure they are up to code. Falk says that a number of the dams in east Idaho are seeing problems and are at risk of failure.

"Earthen dams require a lot closer scrutiny,” Falk said. “They are less resistant to over-topping. Once they start to erode, and water starts to pass through them or over them, they can disappear pretty quickly."

The dam of biggest concern for Falk and his team is upstream from the town of Mackay. Falk says the dam, last inspected in 2014, is leaking near the toe.

"It leaks more than you might expect from an earthen dam," said Falk.

While there is no deterioration at the Mackay dam, Falk worries that a quick snow melt could cause the water to rise face, causing the dam to give way, recreating a scene like we saw 41 years ago when the Teton Dam broke.

“If it were to fail quickly, similar to what Teton Dam experienced, there would be loss of life," said Falk.

The Teton Dam failed on June 5, 1976. It sent a wall of water into the Teton River Canyon. It flooded Rexburg, Sugar City and many of the smaller towns throughout the area. In the end, 11 people died and it cost millions of dollars in property damage.

Another dam of concern is the Oakley dam in Cassia County, which was inspected in 2013. Falk says there is a significant risk of flooding from the dam. Falk says the channel that takes water out of the Oakley dam has been farmed over.

"If the dam had to release a lot of water in a hurry, there is no place for the water to go except through people's farms, homes and well, wherever it may end up," said Falk.

The Mackay and Oakley dams are both consider “high hazard” dams. A high hazard dam gives the dam the most attention.  If a failure of the dam were to occur, the consequences likely would mean a direct loss of human life.

Dams with significant hazard levels are inspected every four years, while low hazard levels are looked at every five years.

Every dam is split into a different classification: low, significant, or high hazard. Each classification has a different timeline on when they must be inspected.

Two other major dams across east Idaho protect us from the risk of flooding. All of them are owned by the federal government.

The Palisades dam was last inspected in 2013 and is considered to be satisfactory. It will be inspected again this year.

Further downstream is the Rire dam. Also classified as satisfactory, it was last inspected in 2013 and will also be inspected again this year.

In the event of a dam failure or emergency situation, the state says there is a response plan in place.

Each dam operator in the state is recommended to have an emergency action plan on file. Falk says every operator of dams in east Idaho has a plan on file.
 


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