Hebgen Dam Failure Threatens Madison River Trout

September 12, 2008 By: Marshall Cutchin

Almost two weeks ago intake tower gates at the Hebgen Lake dam — which feeds water into Quake Lake and the Madison River — failed, causing the outflow from the dam to increase from 850 cfs to just under 4000 cfs in a matter of minutes. There were immediate concerns about the dam’s failure, raised by both Ennis residents fearing total dam failure and by local guides and fly fishing businesses, since Hebgen Lake water levels are closely tied to management of water levels in the Madison, where brown trout are set to begin spawning in early October. Some expressed concern that the water levels in Hebgen would get so low that there would not be enough water to maintain adequate flows in the river through the winter season. Anxieties have risen as PPL Montana, who owns the dam, has so far been unable to repair the headgate damage. But using sonar, engineers have discovered a 150-square-foot hole in one of the four intake towers and yesterday began to replace the damaged stop logs there.
We spoke with Kelly Galloup, owner of Galloup’s Slide Inn just below Quake Lake, yesterday and learned that PP&L, who owns and operates the dam, was making a new effort to replace the 17 boards damaged in the gates. “They feel confident that this time it will work,” said Galloup. We also asked Galloup about rumors that there would not be enough water remaining in Hebgen to maintain the Madison’s winter flows. “There should be plenty of water in there, as long as they fix the problem in the next couple of weeks. We are still eight feet above the historical lows for Hebgen, and whether you think the water is dropping at six inches a day or one foot, there should still be plenty of water in the lake. Just as important is that the the lake get drawn down to reasonable levels prior to the brown trout spawn. The state is required to bring lake levels down to prepare for spring runoff by October, and this has been a very wet year, so it would be just as bad if there was too much water in Hebgen, since high flows will also interfere with brown trout spawning.”