Wildlife workers and volunteers rushed on Wednesday to save thousands of fish stranded by sharply plunging water levels along a Montana river known among anglers for its high-quality trout fishing.
A gate that lets water out of the Hebgen Dam just west of Yellowstone National Park malfunctioned and caused flows in the Madison River to drop early Tuesday morning, according to the dam operator NorthWestern Energy.
This left side canals cut off from the main river and some areas without water.
Photos from the scene showed dead trout and other fish lying on exposed rock beds that would normally be covered with water at this time of year.
More fish were threatened in the cut side channels and there were concerns that the exposed trout eggs could perish, said Kelly Galloup, owner of a fly fishing shop.
Galloup said the larger trout likely moved to deeper pools as water levels fell. But he expected an impact on fish born last year that were too small to escape the sudden drop in flows.
The Madison is a popular “blue ribbon” trout fishery that emerges from Yellowstone National Park in Wyoming and ultimately empties into the Missouri River. The Hebgen Dam is used to control water flows from downstream hydroelectric power stations.
Volunteers began collecting fish from the canals and bringing them back to the main course of the river on Tuesday. That work continued on Wednesday, and officials from Montana Fish, Wildlife and Parks closed fishing along the upper reaches of the river until full flows could be restored.
âWe rowed all day yesterday on the upper reaches of the river,â said Galloup. “We are only focusing on the secondary channels, trying to save whatever we can find.”
More than 100 volunteers took part in the effort to save the stranded fish, using nets to catch thousands before they were transferred to the still-flowing part of the river, said Morgan Jacobsen, spokesperson for Fish, Wildlife and Parks.
âThe turnout was huge,â said Chris Bianchi, who works at the Slide Inn fly fishing shop in Galloup. “There were people everywhere that there was a side channel … The general consensus was that the (lower) part of the river was in much better condition than we thought when we woke up.”
Most of the fish rescued were sculpins with a small number of trout, Jacobsen said.
The extent of the damage to the fishery will not be known until next year, when biologists are able to get a better estimate of the impact of low water on trout spawning grounds, Jacobsen said.
A component needed to fix the failing door was on its way to site, with repair work scheduled to begin Wednesday evening, said Jeremy Clotfelter, director of hydroelectric operations at Northwestern Energy.
âWe know what failed, but we don’t know how it failed or why it failed,â Clotfelter said. He adds that it would take “a few hours” to install the replacement component.
Workers had already started releasing water over the dam’s spillway, resulting in a slight increase in flows, NorthWestern Energy spokesman Jo Dee Black said.