New dam to allow fish passage up Cass River

Frankenmuth, Mich. – A new rock ramp dam on the Cass River near
Frankenmuth will allow fish upstream for the first time in 150
years.

The Saginaw Bay Watershed Initiative Network granted Central
Michigan University $30,000 to study how walleyes and other fish
adapt and reproduce with new access to stretches of prime spawning
habitat upstream.

CMU fish ecology professor Brent Murry will work with students
to monitor egg mats and spawning adult walleyes on the Cass River
this spring, then repeat the process after the rock ramp dam
replaces the dilapidated Frankenmuth dam, likely in August.

“We are going to assess the number of walleyes coming up to the
dam this spring,” Murry said. “It’s baseline data … to get an idea
of what kind of success to expect over the next several years.”

Jim Baker, DNRE fishery manager, said much of the focus is on
establishing a steady walleye run from Saginaw Bay, but channel
catfish, sturgeon, white bass, carp, suckers, pike, and other
species also will benefit from the roughly 73 miles of tributaries
upstream.

Baker said the department also will conduct electrofishing
surveys above and below the dam to monitor how fish are moving
through the system. Officials hope to see better natural
reproduction during coming years “because the current is quicker
(upstream), you tend to have more gravel … and that’s the type of
stuff a lot of these fish like to spawn on,” Baker said.

The rock ramp is a roughly 5 percent grade of rock and stone
riverbed gradually sloped from an impoundment downriver, allowing
fish to pass far more easily than traditional dams. A similar
project was completed last year on the Shiawassee River in downtown
Chesaning.

The roughly $3 million overhaul is funded by the U.S. Army Corps
of Engineers, the city of Frankenmuth, a $50,000 donation from the
Watershed Initiative Network, and other sources, said Michael
Kelly, director of The Conservation Fund, which administers the
WIN.

Several other rock ramps are in place in Minnesota and
Wisconsin, Kelly said, but “none on rivers as large as the Cass
River in Frankenmuth.

“It’s a major construction project best done when water levels
are at their lowest,” Kelly said. “The goal is to get the fish to
pass.

“What we want to do is measure the success” and use that
information to help other areas considering alternatives to a full
dam removal, Kelly said. There currently is little data on how rock
ramps impact a river’s fish, he said.

Murry said he’s working to secure more grants to continue
monitoring natural reproduction in the river for several years. He
believes the Cass could soon hold a self-sustaining walleye stock,
but said that may take as many as five or six seasons to build
up.

“The sooner this goes in, the better for the walleye,” he said.
“We need to establish a run in the Cass River.”