Corps goes state's way on Libby Dam operation

The Daily Inter Lake

The U.S. Army Corps of Engineers intends to follow recommendations from Montana and the Northwest Power and Conservation Council in operating Libby Dam this year, one of Montana's members on the Northwest Power and Conservation Council said Wednesday.

In the wake of a disastrous, unintended spill from Libby Dam in June, Corps officials had indicated a desire to return to highly conservative, standard flood-control operations at the dam.

But Montana and the council urged the Corps to continue with a properly implemented variable discharge - VARQ - operation at the dam. They contend that such an operation would make more-efficient use of water for power production and fisheries, and would increase the likelihood of refilling Lake Koocanusa, by adjusting the reservoir's refill based on runoff forecasts.

By contrast, operating the dam under flood control involves deeply drafting the reservoir during the winter months, with a lower probability of refilling and having enough water available for fisheries.

Bruce Measure, one of Montana's two representatives on the council, said he was recently informed by the Corps' northwest divisional director, Karen Durham-Aguilera, that VARQ would be implemented at Libby Dam this year.

"She informed me that they would be operating Libby Dam under strict VARQ for 2007," Measure said from his office in Helena.

The summer's 19-day spill caused extensive flood damage to levees and agricultural lands near Bonners Ferry, Idaho, as well as gas bubble trauma to fish below the dam. Releasing water over the dam's spillway increases gas saturation in the river, causing "bubbles" to develop on exposed fish. Although it is believed that most fish recover, biologists are uncertain whether the trauma causes long-term damage to fish.

Last fall, the Corps came out with an "After Action" report that acknowledged that the spill could have been avoided, had Libby Dam been strictly operated under VARQ guidelines.

But then there were indications that Corps officials wanted to revert to the more conservative flood control operations.

"They expressed concern about operating to VARQ because they thought they should be extremely conservative from this point on," Measure said.

Montana officials countered that VARQ, if properly implemented, can err on the side of flood-control safety rather than trying to meet the additional goal of refilling the reservoir to full pool.