Accident causes Boise River to run dry

Barber Dam on the Boise River is undergoing repairs, which in part contributed to the complete dewatering of the Boise River Feb. 4. (Photo by Liz Paul)

The gauge at Glenwood Bridge on the Boise River shows the dramatic drop of the Boise River Feb. 4.

BOISE--In the early hours of February 4 water stopped flowing through the Barber Dam hydropower plant on the Boise River and resulted in a sharp drop of flow in more than 15 miles of the Boise River through Idaho’s capital city.

Below Barber Dam, the flow was reduced to leakage for more than six hours, underscoring a significant failure by federal, state and local officials who did not correctly anticipate the combination of circumstances that caused the accident.

“Biologists can’t say with certainty what impact this serious accident had and will continue to have on the Boise River, but it’s safe to assume that the loss of water caused irreparable harm to fish and aquatic insects,” said IRU Boise River Campaign Coordinator Liz Paul. “The entire food chain will likely be impacted, as will fishing opportunities.”

Barber Dam Project, a 25-foot-high facility located three quarters of a mile upstream of Barber Park, was issued a 40-year operational license by the Federal Energy Regulatory Commission (FERC) in 1983. Ada County and a multi-national power company, Enel, are the co-licensees. 

The story of Barber Dam goes back to 1906 when the 1,500-foot-long, 25-foot-high, dirt-embankment and timber-crib dam was built by the Barber Lumber Company to provide power for its sawmill. A new powerhouse was built when the project was licensed in 1983. 

Stability concerns with the aging dam were dismissed by FERC in 1983 when the timber-crib section of the dam was found to be susceptible to horizontal movement. In its December 23, 1983 order issuing the operational license, FERC said: “failure of the dam during extreme flood flows would be gradual and would not impose a hazard to downstream life.” 

During the last 30 years, Barber Dam has continued to deteriorate, and major and minor safety repairs have been made to the structure to stem leaks and other problems.

Deterioration at Barber Dam was, in part, to blame for the Feb. 4 drying of the Boise River, Paul said. A large repair project is currently underway, and extensive work is being done on the front and back of the dam. The pool behind the dam was drawn down a few feet to facilitate access to the work area. 

Under normal operating conditions, all of the river’s winter flow, about 250 cubic feet per second, passes through the dam’s powerhouse. If the turbines go offline for any reason and water can’t flow through the powerhouse, the river will almost immediately flow over the dam spillway.

Because the pool was drawn down for repairs Feb. 4 when the turbines went offline, the river couldn’t flow over the spillway until the pool level rose hours later. The Boise River went dry. The long duration of the event was caused by a complete failure of the dam’s emergency alert system, meaning nobody noticed, and work to fix the problem didn’t start for a prolonged period.

“While the damage can’t be undone, steps can be taken to prevent similar problems in the future,” Paul said. “Aging dams like this require increased scrutiny, and with the permit expiring in 2023 it’s time to begin discussions about the future of Barber Dam. It may be time to decommission this aging old dam and restore a section of the Boise River.”