Rising water levels in Borderlands lakes and rivers is both good and bad for fish, wildlife and habitat

While humans may be very troubled and inconvenienced by high water levels this spring in Borderland, wildlife and fish are pretty well adapted to those fluctuations, according to area resource specialists.
“Fluctuations occur in the natural environmental all the time,” said Kevin Peterson, Minnesota Department of Natural Resources area fisheries supervisor.
Lee Grim, biologist at Voyageurs National Park agreed.
“Birds have been going through this a long time as a species,” he said. “There’s lots of variable impact.”
And it’s business as usual for beaver, according to Dick Lorette, DNR wildlife technician.
Fish can benefit from the flush of nutrients into the waters from rains, but at the same time, sediment washed into the waters can impact incubating eggs, and high levels can erode habitat, according to Peterson.
A study of water levels on Rainy Lake over several decades sought trends in the fishery, he said.
“There was a positive relationship between extreme events and fish production,” he said. “We don’t want to experience extremes every year, but periodically, it’s good for the aquatic ecosystem.”
Some fish have spawned and hatched their young, which makes them mobile. “They can adapt to fluctuating water levels better than some of the invertebrates,” Peterson said. For example, mussels, or clams, crawl along the bottom of lakes and rivers and can be impacted more by rapid changes in water levels.
But some fish, including lake sturgeon, spawn later than other species. He said he’s been hearing recent reports of sturgeon spawning in Rainy River below the international dam. “Sturgeon are fairly well adapted, they spawn in areas of strong current, so I don’t think this will bother them, but it could be bad for sturgeon eggs if we get a rapid decrease in water. That could leave those eggs high and dry,” he said.
However, Peterson said he doesn’t expect the river level to drop soon, unless flooding problems arise quickly downstream.
In general, he said rapid fluctuations are not good for the aquatic community.
Peterson noted that this high water event is coming on the heels of two years of drought, which also impacts fish and wildlife.
The weather has kept Grim from flying with park pilot Scott Taylor to check on eagle and osprey nests in Voyageurs. However, he said Thursday he was scheduled to fly in the afternoon.
In the meantime, he said he has been surveying loons, which nest on land. Rising water has flooded some loon nests, but Grim pointed to a loon nest created on a floating cattail mat.
Eagle parents must protect eaglets, which could now range in age from three to six weeks, from cold and rain. If the rain and wind become too severe, the parents will abandon the nest leaving the young to likely die from exposure.
Ground nesting birds, such as ruffed grouse, can also be impacted by this spring’s cool temperatures and rain.
“But birds are a lot tougher than we think,” he said.
Lorette, who has spent recent days in he woods placing beaver meat laced with tetracycline for a DNR bear study, said the forests are very wet.
But newly born kits of beaver who build dens on ponds should be OK, he said, because they will construct dams to slow the rising water. But beaver with dens on the banks of rivers and lakes may be displaced because they can’t control the water levels.
He noted that beaver, as well as mink and otter, will move their young to safer dens under some situations.
Lorette cautioned those who are wishing for warmer weather, which is forecast for next week.
“It’s going to get steamy and hot,” he said. “Then the mosquitoes will be out. Now, it’s just the big slow ones that are out. Then we’ll get the little, fast biting ones and look out.”