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Montana Rainstorm Prompts Hydro Managers To Consider Libby Dam Outflow Regime
Posted on Friday, September 24, 2010 (PST)

Sometimes Mother Nature doesn't cooperate with government biological opinions, and that was the case this week with heavy rains in the Kootenai River basin.


The basin received between 1 1/2 to 2 inches of rain Sunday and early Monday, increasing water inflows to Lake Koocanusa up to a point where it was apparent that an end-of-the-month target elevation for the reservoir could not be reached without changes in Libby Dam operations.


That prompted an emergency teleconference Wednesday for the interagency, four-state Technical Management Team that helps guide hydroelectric operations throughout the Columbia River basin.


The panel considered two options: immediately increasing Libby Dam outflows from 9,000 to 12,000 cubic feet per second or maintaining 9,000 cfs flows and missing the Oct. 1 target elevation of 2,439 feet.


The panel chose the latter by consensus after hearing from Jim Litchfield and Brian Marotz, Montana's representatives on the panel.


They maintained that the need to avoid biological harm on the river below the dam outweighs the need to meet the elevation target that is included in a federal biological opinion for Libby Dam operations.


Suddenly ramping up the river would adversely affect fish and other aquatic life at a time when the river is still in its most biologically productive "growing period," Marotz said.


With flows maintained at 9,000 feet, the target elevation will be missed only by a foot on Oct. 1 and it is expected to be met within just a matter of days after that date.


As of Wednesday, the elevation of Lake Koocanusa was 2,441 feet.


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