DULUTH — Hundreds of brook trout, minnows and other fish —along with crayfish and aquatic bugs — have died in Tischer Creek in Duluth’s Hunters Park neighborhood and biologists aren’t sure yet why.
The fish kill was first noticed by neighbors who reported seeing the fish belly-up starting Thursday morning.
Dan Wilfond, Duluth-area fisheries supervisor for the Minnesota Department of Natural Resources, said both DNR and Minnesota Pollution Control Agency crews have taken fish and water samples to be submitted to a lab in St. Paul next week. Until the toxicology report comes back, Wilfond said it’s not clear what the problem was or is.
Contributed / Natalie Trieschmann
“We counted about 250 dead fish in about a quarter-mile stretch. But it’s not just the fish. … Everything in the stream, crayfish, invertebrates, all got hit by whatever it is,’’ Wilfond said.
Areas above a culvert near Hartley Park did not appear impacted by the problem, Wilfond said, while areas downstream were hardest hit.
While warming water during hot weather can cause trout to die off, this fish kill appears too large and too rapid to have been a water temperature issue, Wilfond and others noted.
Wilfond said that whatever was in the water may already have flushed downstream and diluted, but he said it might be best for people and pets to avoid the creek until more is known.
There is considerable construction ongoing in the area, along and near Woodland Avenue, but Wilfond said crews had not found an obvious source of the problem.
“We’re not going to point any fingers at this point,’’ he said.
Some neighbors said a bridge construction project and stream diversion where the creek crosses under West St. Andrews Street may be the source of the problem, noting there appeared to be a sheen on the water in that location where a large pump is running.
Contributed / Natalie Tresichmann
Tischer Creek is a designated trout stream, one of many in Duluth that are under pressure from warming water temperatures, polluted runoff, sedimentation and other factors from urban development. But coldwater springs, coupled with efforts to improve habitat in and along the streams, have helped trout hang on in recent years.
John Myers reports on the outdoors, natural resources and the environment for the Duluth News Tribune. You can reach him at jmyers@duluthnews.com.
