Before the dam, there were an estimated 10,000 Kootenai sturgeon. Fewer than 500 mature adults of spawning age remain. The effort this week will spill up to 10,000 cubic feet of water per second over the dam in a huge waterfall for up to seven days, in what scientists hope will push the sturgeon to more productive spawning grounds in Idaho. The water will spill from Koocanusa Reservoir into the Kootenai River, where scientists hope the sturgeon will swim to the Bonners Ferry area. The U.S. Army Corps of Engineers on Tuesday began sending more water through the dam's turbines, in preparation for opening spill gates on Thursday. "The idea is to recreate more of the natural, spring conditions," said Michael Milstein of the U.S. Bonneville Power Administration, which markets the power from the dam. "That is believed to be a factor that led sturgeon upriver to spawn."