Tucked alongside the Duschee Creek south of Lanesboro, a state-owned hatchery is undergoing a multimillion-dollar redo that will help keep brown and rainbow trout thriving in Minnesota’s lakes and streams.

The Minnesota Department of Natural Resources is replacing the hatchery building that houses its offices and a nursery.

“It was old and basically to the point where the structure was crumbling and compromised,” said hatchery supervisor Scott Sindelar.

The list of problems was long — support beams that were nearly rusted through, mold, a leaky roof, high levels of radon and nitrogen and problems with electrical, heating and plumbing systems, he said.

Left unchecked, those problems could eventually affect fish production at the state’s flagship trout hatchery, which opened in 1925, Sindelar said.

Construction began on the $5 million project April 1 and is expected to be completed by November. The work shouldn’t interfere with egg hatching and fish production, Sindelar said.

The hatchery, which is the largest of the DNR’s four cold-water hatcheries, annually produces about 750,000 fish that are stocked in hundreds of lakes and streams across the state.

“Trout need optimal water quality. It has to be cold, fresh and flowing,” Sindelar said. “We have the highest flow of groundwater, the biggest springs, so we produce the most fish.”

And that’s good news for a sport that’s becoming more popular in Minnesota, where walleye has long reigned.

“There’s a lot of concern that there aren’t as many people angling in general,” said John Lenczewski, executive director for Minnesota Trout Unlimited. “But actually, trout angling is one area that has been growing steadily. We have more [trout] anglers than duck hunters. More [trout] anglers than pheasant hunters. It’s not like walleye, but it’s the one area of angling that’s growing.”

The increase over the past five years may be due in part to the purchase of easements that make fishing more accessible and a winter season that allows anglers to cast a line for trout nearly year-round — from Jan. 1 to Oct. 15 f in some areas, according to Brian Nerbonne, DNR regional fisheries manager. In addition, lakes — not just streams — are being used by anglers as trout destinations, he said.

Improvements to habitat have allowed fish to prosper, and that’s creating good spots for people to fish, Nerbonne said.

“The abundance of trout in southeast Minnesota is at an all-time high,” he said. “Trout fishing has been as good as it’s been in anyone’s lifetime right now.”

And that’s been an economic boon for the region, with anglers spending money on lodging, food and fishing supplies.

By opening day of the stream trout fishing season next weekend, Lanesboro will come alive.

“People will be elbow-to-elbow fishing. They’ll be all up and down the rivers and creeks,” said Tom Smith, Lanesboro City Council member and a longtime trout angler. “You won’t find a spot to park. The campgrounds will be full.”

The Lanesboro hatchery often attracts tourists who want a glimpse of how fish are made — from the incubators where eggs are hatched to the tanks where they grow before being released into lakes and streams.

“Stocking these hatchery-raised fish in a scientifically sound manner significantly enhances fishing in Minnesota and provides angling opportunities that wouldn’t be there without stocking,” said Brad Parsons, the DNR’s fisheries chief.