A Power Outage May Have Caused The Boise River's Sharp Drop Overnight

Feb 4, 2015

This story was updated at 4:55 p.m.

You might have noticed the Boise River was lower than normal Wednesday morning. At midnight, the gauge at Boise's Glenwood Bridge showed the river was flowing at 290 cubic feet per second (cfs). At 10:45 a.m., the river had dropped to just 81 cfs. 

Ryan Hedrick is a hydrologist at the Bureau of Reclamation, the agency that controls the flow of water to the river at Lucky Peak. He says the significant drop this morning was due to a problem at a Boise hydroelectric plant in the middle of the night.

"It appears that [the powerhouse at] Barber Dam was shut down," says Hedrick. "And when that happens, water has to build behind the dam until it's full enough to spill over the top of the dam and water will then continue downstream."

Hedrick says the bureau monitors readings every 15 minutes, and this drop was significant. He says people often call to report when the river is down and the bureau was alerted to this morning's low flow.

"There was concern that the river was down, so then we have to do investigative work if it wasn't us [slowing the flow]."

This chart shows the steep decline in the Boise River's flow Wednesday.
Credit USGS Idaho

But by noon, the river was back up to a more normal flow in town. Hedrick says he's not sure exactly what happened at Barber Dam to cause the flow to drop so dramatically, but he's not too worried about it.

"I suspect it's happened before, it's just one of those anomalies," says Hedrick.

Barber Dam is owned by Enel Green Power, an international hydropower company.

The company's regional operations manager Larry James says they're is still trying to figure out exactly what went wrong at Barber Dam. But he suspects a slight fluctuation in the Idaho Power grid caused the hydroelectric plant to shut down, causing water to back up behind the dam.

James says the plant went down at 10 p.m. Tuesday, and the automatic alert system also failed. The company’s Boise staff got the plant running again around 6 a.m., but it took several more hours for flow to return to normal on the river.

James says his company is investigating their equipment, and will make any upgrades necessary. He says this is the first time the Barber Dam systems have failed for an extended number of hours.

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