Fish kill reported at 4x4 Road bridge
April 3, 2019
The bitter cold temperatures that gripped the area in February and early March is believed to be the culprit behind a fish kill near the bridge at the end of the 4x4 Road, east of Lincoln.
Billy Smock of Lincoln noticed dozens of dead fish around the bridge Friday while out walking in the area. She reported the kill to Lincoln-area Game Warden Ezra Schwalm, who arrived that afternoon to check it out.
At first, Schwalm didn't suspect cold weather or ice was the cause.
"This spot doesn't typically freeze like that," Schwalm said "The biggest worry would be that someone dumped something here, some chemical or something."
Schwalm contacted Montana Fish, Wildlife and Parks fish biologist Pat Uthe with his concerns, but those began to fade as he looked more closely at the river and noticed the ice at the edge of the open water was still frozen down to the rocks on the river bed.
While watching the river downstream from the bridge, a large slab of ice on the bottom of the river that first appeared to have slid under another slab, cracked loudly and floated to the surface as the now-flowing water freed it from the riverbed.
Lincoln Ranger District Fisheries Biologist George Liknes arrived minutes later and agreed that, though it was unusual, the combination of low water flow and prolonged cold most likely allowed for the formation of anchor ice around the area of the bridge. The dead fish, if not killed by the ice itself, were probably isolated in pools that became cut off from the oxygen in flowing water. Liknes said he's seen that in instances where floods from ice jams killed fish by trapping them in pools away from moving water.
Likewise, thick ice and snow can cover an area and block light from reaching oxygen-producing aquatic plants, which kills them and in turn deprives fish of oxygen. More likely in ponds and lakes, it is believed to have been the cause of the fish kill reported at Browns Lake last year.
Schwalm and Liknes made a second call to Uthe to who agreed with Liknes' assessment, which was backed up by a report from Brock Kuntz, a resident of the area who walked down to the bridge regularly. He confirmed for Schwalm and Liknes the river had only started flowing freely near the bridge around March 25 and that it had been frozen over there.
Most of the fish killed in the area were whitefish, but a few trout, including one 20-inch cutthroat, were among the casualties. Liknes investigated the river further to look for more dead fish, but the BVD was unable to follow up with him before going to press.
Kathy Schoendoerfer at the Blackfoot Anger in Ovando said she hasn't heard of any other reports of fish kills on the Blackfoot River, and said late last week Browns Lake was still frozen over.