When Xcel Energy removed its Minnesota Falls dam on the Minnesota River in 2013, an underwater surprise was revealed a few miles upstream.
Waiting for modern eyes to see was the rock-filled cribbing that was the base of a dam that spanned the river immediately downstream of the present day U.S. Highway 212 bridge in Granite Falls. The “old power dam” as it was called in a 1900 plat book may have been built as early as 1871. It’s base had been hidden underwater for 108-years by the higher waters the Minnesota Falls dam had created when it was built in 1905.
The now revealed, old dam became an immediate problem, according to Chris Domeier, fisheries supervisor with the Minnesota Department of Natural Resources in Ortonville. It was just high enough to make boating and canoeing dangerous on this section of the river.
Its presence also served to hinder fish migration, and took away the natural riffles and rapids that provide important habitat for fish and other aquatic organisms in the river.
Added to these issues was the way the old dam diverted the river’s flow to the west bank of the river, scouring it and in the long term, potentially creating concerns for the Highway 212 bridge.
“The issue became, who is going to take care of it?’’ said Domeier.
He spoke last week as the problem was taken care of, and in a way that will benefit boating, canoeing and fishing in the river in a very big way. It took three days of work in the river to restore the old dam site into a more natural rapids area.
High water flows in the river had delayed the project for nearly two years. The U.S. Army Corps of Engineers held water back at Lac qui Parle Lake to aid the work this season.
A grant from the Lessard Sams Outdoor Heritage Fund made the project possible, said Domeier, in large part because of the benefits it will provide for fish in the river.
“This is the best lake sturgeon spawning habitat in the Minnesota River,’’ said Domeier as he pointed to the V-shaped rapids created below the Highway 212 bridge.
Dr. Luther Aadland with the Minnesota DNR, who has built an international reputation for restoring fish habitat when dams are removed from riverine systems, oversaw the restoration. Its goals are to restore the spawning habitat needed by the river’s rock stars: Lake sturgeon, paddlefish, walleye, and sauger among them.
The stretch of river that exists from the former Minnesota Falls dam to the Granite Falls dam is unique in the Minnesota River system, according to Aadland. The approximate 17-foot drop in elevation along the stretch creates a series of riffles and rapids. Boulders are naturally dispersed in the stretch. Combined with the relatively steep drop, it makes perfect habitat for a wide variety of fish, including many of the small, forage fish on which game fish feed.
It also means there is an approximate, 250-mile stretch of the Minnesota River from the Granite Falls dam to the Mississippi River that is free flowing. That makes it one of the longest, free-flowing river stretches in the entire state.
Aadland has been part of research that is showing that fish naturally migrate long distances in river systems. Radio tags have tracked sturgeon that migrated in the Mississippi River from near the Iowa border to locations in the Minnesota and St. Croix Rivers to find the spawning habitat they need. They returned to the waters near Iowa within two weeks, indicative of how important the right spawning habitat is for this species.
There are walleye in the Missouri River system that annually make 200 mile migrations.
Aadland said he has little doubt that once discovered, this newly-restored site will attract many fish species for spawning.
He noted too that the removal of the Minnesota Falls dam has removed a barrier to fish migration, and reduced the river fragmentation that has kept many species of fish from upstream habitat they once occupied. Since its removal, 12 of the 39 native species that had been blocked have now returned upstream, according to a study published in 2015.
The study found that the Granite Falls dam keeps 39 native species from returning to natural, upstream habitat. The city and the DNR are exploring the possibility of developing a fish passage at the dam site.
Anglers have already discovered the improved fishing opportunities now found upstream of the former Minnesota Falls dam site, noted Domeier. He anticipates that in the next couple of years, they will also discover that some of the best fishing in the river will be found right where the newly-restored rapids are found.