How Do Professionals Manage Local Trout Streams? Often, It’s Through Explosives
In this line of work, projects don’t start with a bang.
They end with one.
With a booming explosion on Tuesday morning, a portion of stream at the headwaters of Big Haymeadow Creek in Langlade County again flowed freely, a beaver dam blasted out of the way.
Jeremy Irish, an assistant district supervisor with the USDA’s Wildlife Services program, triggered the blast, undoing some of this year’s construction by beavers in the area. In the process, he cleared another portion of one of northern Wisconsin’s best trout streams.
Hundreds of miles of northern Wisconsin’s best trout streams flow freely, providing excellent fish habitat and great fishing.
But if beavers, and they dams they create, had their way, the landscape would be much different.
Often, it’s humans like Irish who have to help strike the balance, doing it using fuses, detonations, and explosions.
Beavers improve their own habitat by creating dams and ponds, Irish said, but hurt other animals in the process.
“Beaver are a very unique animal. They can alter their habitat to suit themselves, and in the north here, they definitely need to do that to make it through the winter,” he said. “The difficulty is, in altering their habitat, they also create problems for other species. In this case, we’re talking about a cold water ecosystem to support brook trout populations and spawning habitat.”
Wading upstream from the site of the first blast, he and USDA wildlife specialist Brian Olson came to the biggest beaver dam on the site. It’s a solid structure creating a basketball-court-sized pool several feet deep.
“It’s a whole different environment on the top side of the dam,” Irish said. “It’s a stagnant pool, flooded debris, whereas the backside of the dam is channeled and the water’s flowing.”
Irish plans to blast this dam, too. But he’s only at this point after the work done Olson in the preceding weeks.
With a special rake, Olson has hand-pulled smaller dams, the USDA’s method for removing more than 80 percent of nuisance beaver dams in Wisconsin.
Olson has also trapped and removed the beaver from the site in anticipation of blasting.
“I came in here every couple days all last week,” Olson said. “I caught the five beaver out of here.”
The surveying, dam-pulling, trapping, and blasting may seem like a lot of work for a stream just a few feet across. But it’s worth it, said Dave Seibel, the DNR fisheries biologist for Langlade and Lincoln counties.
“That’s a pretty major tributary to the Prairie River. The Prairie River is a high-quality trout stream. That’s also one that’s on the list,” Seibel said. “We do want to get the most bang for our buck, so we do want to focus on the really good trout streams that wouldn’t be so good if they got all ‘beavered up.’”
“Beavered up” streams stop the free flow of water, raising water temperatures in pools along the way.
“Trout are cold water species,” Seibel said. “They need cold water. It’s not just a preferred temperature range. It’s an absolute need. Otherwise, they die.”
Seibel and his colleagues in the DNR and Chequamegon-Nicolet National Forest keep a list of the best trout streams in northern Wisconsin. Those are the streams USDA Wildlife Services maintains with staff like Irish and Olson in the field.
All told, it’s about 1,800 miles of streams in northern Wisconsin.
Decades ago, many were clogged with countless dams. Now, with many of the dams gone, Wildlife Services can focus on maintenance.
“Because of that long-term consistency, it has really showed results,” said Bob Willging, a USDA Wildlife Services district supervisor based in Rhinelander.
His agency’s practices fit within the DNR’s Beaver Management Plan, a product of years of input and planning.
The current, overhauled version was published in 2015.
“It’s surprising how many people are interested in beaver management,” Willging said. “That’s a good thing. There are people interested in beaver management from many different sides.”
Sometimes, beaver management can be controversial. Trout fisherman want free-flowing streams free of beaver dams. Waterfowl hunters like the habitat the beaver ponds create.
But Willing feels the Beaver Management Plan considered and addressed the interests of all groups.
“I think it addressed everybody’s concerns,” Willging said. “So far, it seems like it did a really good job of balancing all of the different interests."
Back at the Big Haymeadow Creek headwaters, Irish and Olson were working on scouting the main beaver dam, forming a blast plan.
Irish mixed six pounds of explosives – on the high side of average, he said – to attack this dam.
He then attached a detonation cord, which has a burn rate of 23,000 feet per second.
Irish sent everyone to shelter a few hundred yards away.
After calling “fire in the hole” and sounding an air horn, the blast obliterated the dam.
“We had a nice cracking sound there. It sounded very good. You can see we’re moving a lot of water. There’s no debris in it,” Irish said upon inspecting the impact.
The beaver pond began draining rapidly. Within minutes, the water level was down a few feet and mud flats started to appear.
It won’t take too long for the transformation into good trout habitat to be complete.
“What’s really neat is to look back at these. Sometimes it’s a week later. Sometimes it takes a month or two later. But you’ll start to see the banks setting up and getting green. You really get to see the effects, the longer-term effects of what you accomplished. It is rewarding,” Irish said.
Irish couldn’t stay long, headed instead to the next site.
After all, each year, he blasts around 100 beaver dams.