What if the Moyie Dam fails?

BONNERS FERRY — If Moyie Dam fails, how will the Twin Rivers area be impacted?

The city of Bonners Ferry will attempt to answer that question with the completion of an inundation study.

The last study done in 1998 did not specifically answer how Twin Rivers would be affected, which is the only area at risk. The upcoming study will provide information on what will get inundated and at what levels under different scenarios.

Current estimates are that water levels would rise two to six feet above normal water levels in the Moyie River at Twin Rivers.

“The chance of the dam failing is remote,” said City Administrator Stephen Boorman. “We are lucky with the structure we have.”

The Moyie Dam is a solid concrete dam 92 feet high and wedged into solid rock. The reservoir behind the dam is approximately one mile long.

Boorman said there has only been one solid concrete dam failure in the United States.

In the event of a failure, once the water reaches the Kootenai River it won’t be a major issue. The Kootenai River would only rise a few inches. according to Boorman.

The inundation study is a requirement of the Federal Energy Regulatory Commission (FERC), which controls all dams on public land in the United States. FERC also requires inspections every five years. The inundation study should be completed in a few months.