The flow on the Madison River below Hebgen Dam was restored to normal flows at near midnight on Wednesday after a failure cut off flow to the Upper Madison River for nearly 48 hours.
While flows into the Upper Madison are back to their previous levels, there isn’t a good understanding of the impacts.
“There was some mortality observed, although it could have been much worse,” explained Montana Fish, Wildlife and Parks (FWP) spokesperson Morgan Jacobson. "We are glad that it wasn’t worse than it was,” he said regarding the fish stranded on the banks after flow was cut off.
Biologists and volunteers ventured out to salvage fish on the river that were left in shallow pools and side channels on Wednesday.
When the dam failure was first discovered on Tuesday, FWP had concerns about asking people to go out to salvage fish. The first concern was public safety. If the water was restored to the river, volunteers could get trapped or drown in the quickly rising water.
The other concern was the exposed spawning areas for rainbow trout and other fish called redds.
“A redd is a place where fish lay their eggs and it is there until they hatch” Jacobson explained. “When we see water levels drop, some of those redds become exposed to the air and the cold temperatures” he continued.
Jacobson explained that the redds could be viable even out of water for a short time. Cold temperatures and exposure could damage the viability of those eggs.
Getting water restored to the river is key to the survival of those redds and NorthWestern Energy was working around the clock to fix the damaged dam which was restored early Thursday.
Even with water restored to the river, there are no answers to the damage that was done. “Whether those redds remain viable, and how that recruitment looks will take more than a year to learn what that looks like,” Jacobson said.
From an angler’s or outfitter’s standpoint, the restoration of the river flow was a relief, but still a concern on the fishery.
Dan Lohmiller who is an owner and guide of River Edge Fly shop in Bozeman, says that most anglers may not even realize if the damage is done initially.
“If the actual eggs were affected, you know, in the short term you might not notice it,” he said. “But in the long term you might lose a whole age class of fish” he continued.
Brown trout populations in the upper stretch of the Madison River have been a concern for a few years. Declining numbers of brown trout are noticeable to anglers, and without a good definitive explanation as to why.
“It seems to be a long-term trend on the recruitment of brown trout,” Lohmiller said of the Upper Madison River. “I'm not sure that anybody knows exactly why, but obviously this isn't going to help that situation in the Madison” he explained.
Closures on the Madison River were lifted Friday morning, but nobody that regularly fishes the river is acting as nothing happened. Several guides and anglers were amazed that the river was going to open up so quickly after such a potentially devastating event on the fishery.
The fact remains that the closure of the river regularly depends on water temperatures and flow levels on the river. With the flow back to pre-failure levels, the river can open to anglers once again.