Benefits of dam’s removal will reach all the way to Mississippi River
MINNESOTA — Removing the Minnesota Falls dam on the Minnesota River will have implications reaching all the way to the upper Mississippi River basin, more than 300 river miles distant.
With the dam’s removal, the Minnesota River will again free fall over granite bedrock and boulders along the reach of river extending three miles upstream to the Granite Falls dam.
The long stretch of whitewater is expected to attract more than recreational paddlers.
“This is going to be outstanding spawning habitat” for river and lake sturgeon, paddlefish, walleyes and many other species, said Luther Aadland, a river ecologist with the Minnesota Department of Natural Resources in Fergus Falls.
“This kind of habitat really is key, not only to the Minnesota but to the upper Mississippi as well,’’ he said.
The Minnesota River has a relatively low gradient for most of its 335-mile run from Big Stone Lake to the Mississippi River. There’s one important exception. It drops 50 feet in a seven-mile reach in the Granite Falls area.
The Minnesota Falls site itself is expected to include a small “falls,’’ and a cascade of rapids possibly 500 to 600-feet in length.
This area had historically provided important spawning habitat for native fish species all the way to the Mississippi River, especially large lake sturgeon. Adult lake sturgeon will migrate hundreds of miles to reach desired spawning habitat, said Aadland.
A tagged, lake sturgeon from Lake Pepin had been caught (and released) at the Minnesota Falls site last year, evidence of how far sturgeon will migrate. The tagged fish was not an adult.
For more than a century, the presence of the Minnesota Falls dam has been a barrier for the upstream migration and spawning of a variety of fish. River and lake sturgeon, paddlefish, and sauger are among the fish that are found below the Minnesota Falls dam, but not upstream of it.
Aadland said it’s hard to predict how quickly the fish will return to the site, but he is confident that in future years large lake sturgeon and paddlefish will be among the native species returning to these spawning grounds.