Excess releases of water from Lake Koocanusa should be halted immediately, a Northwest Power Planning Council fish and wildlife staffer says.
Mark Reller said the flow last week at Bonners Ferry, Idaho, exceeded 38,000 cubic feet per second and should be cut back to the target level of 35,000 cfs.
Excess flows are costing Lake Koocanusa 6,000 acre feet a day, Reller said. Excessive releases now will mean less water in the reservoir this summer. An acre-foot is the amount of water it takes to cover 1 acre 12 inches deep.
The increased releases are part of a program to aid white sturgeon by simulating spring runoff, thereby spurring the fish to spawn for the first time since the dam was built.
Last week, the Corps of Engineers released water from Libby Dam at a rate of 23,700 cfs.
Traditionally, the corps has capped flows at the legal minimum of about 4,000 cfs to capture spring runoff.
The U.S. Fish and Wildlife Service has said it would approve cutting back releases in northwestern Montana to meet the 35,000 cfs goal at Bonners Ferry.
Brian Marotz, fisheries biologist for Montana Department of Fish, Wildlife and Parks, also said the releases from Lake Koocanusa were too early. He said the federal government picked an arbitrary date of May 1 to begin releasing water from Lake Koocanusa to mimic spring flows.
Dam operators would do better to make the most of natural runoff from tributaries downstream from the dam, like the Yaak and Moyie rivers, and save reservoir water for later, he said.
One problem with releasing water early is that rainbow trout below the dam are now spawning. If flows are reduced, their eggs will probably be stranded.
Earlier, Marotz also formally requested that dam operators adjust flows from Libby Dam to follow natural runoff. However, he acknowledged it may be difficult to do so, since sturgeon have already moved to spawning areas in response to higher flows.
Biologists in Idaho are monitoring radio-tagged sturgeon to see how they respond to the spring water release.