The U.S. Army Corps of Engineers has acknowledged it could have done a better job managing – and perhaps preventing altogether – a June flood of the Kootenai River near Bonners Ferry, according to results from the agency’s internal investigation.
A report detailing the corps’ actions during the weeks leading up to the flood was posted on the agency’s Web site Friday afternoon.
The river spilled over its banks and into surrounding crop fields after the corps was forced to release massive amounts of water over Libby Dam, 70 miles upstream from Bonners Ferry, to make room in the reservoir for a surge of heavy rain and snowmelt.
Although the report points out several shortcomings, including poor communications and inaccurate forecasts, a top official with the agency said the incident underscores the difficulty of trying to operate a dam under so many competing demands.
“Given the information we had available at the time we made decisions, we did pretty well, actually,” said Jim Barton, chief of water management for the agency’s northwestern division.
The corps was trying to prevent floods downstream and ensure enough water remained in the reservoir for summer boating, while at the same time provide pulses of water to boost the breeding success of downstream salmon and sturgeon.
“One thing we’ve realized is maybe we can’t provide everything to every different purpose for all occasions,” Barton said. “We are trying to balance so many different competing demands.”
Barton said the agency is still determining how to improve and implement changes to Libby Dam operations. He said the changes are expected to be ready next month, well before the next runoff season.
The dam is typically operated to keep the reservoir as full as possible in summer and lower in winter to make room for incoming snowmelt and rain. To help struggling fish populations, the agency recently implemented a new dam operations system.
But the system, known as variable flow, was not fully implemented, according to the report. If it had been, there would have been no need for massive amounts of water to be spilled over the top of the dam.
The variable flow guidelines called for the corps to be releasing four times as much water as it had been releasing in April, two months before the flood.
But the corps kept the discharge from the dam at the lowest level allowed because complicated computer models and forecasts warned the reservoir might not fill with enough water in summer, according to the report.
All information “indicated the risk was low that local flooding would occur,” according to the report.
But the forecasts and models were wrong. By May, the corps could not release water fast enough to make room for an incoming flush of water brought on by a rapid snowmelt and record rains.
In early June, a decision was made to make an emergency spill of water over the top of the dam. This not only sent the river slightly above flood stage for a day, the spill also killed or injured untold scores of fish, including threatened bull trout.
In the months following the flood, local residents as well as biologists for the state of Montana and the federal government criticized the corps, saying the flood could have been prevented and fish saved.
According to the report, the corps spent $1.4 million on emergency response activities during the flood, including delivering 80,000 sandbags to downstream residents and conducting an emergency levee repair in Bonners Ferry.
The analysis of the flood was prepared by the corps. The incident has also triggered an “extensive” review of forecasting models and procedures used by the National Weather Service, according to the report.
“We recognize there’s room for improvement. It’s not our objective to have flooding happen like it happened this year,” Barton said. “There’ll definitely be some changes.”