By the end of the week, 50 boulders will be dropped into the Rock River as part of the restoration project near the site of the former Monterey Dam.
The boulders and the shoreline restoration are meant to “re-create what the river was like before (human) settlement,” said Paul Woodard, city public works director.
Placing boulders in the river will help the fish habitat and create erosion control, said LaVerne Luchsinger Jr., boat captain and project manager with Drax, the general contractor for the restoration project.
Large rivers, such as the Rock River, have sand and silt bottoms that do not provide much habitat for aquatic insects, said Michael A. Miller, stream ecologist for the state Department of Natural Resources, in an email to The Gazette.
Aquatic insects are the base of the food chain for fish, turtles and other river animals, Miller said.
Boulders provide attachment sites for the insects and refuge for fish from the current, Miller said.
“If you had to swim 24/7 against the current of the Rock River, you would be a pretty skinny fish and wouldn’t lay many eggs,” Miller said in his email.
Some fish species scatter eggs among rocks. Eggs settle into rock crevices where, once hatched, small fish can “seek refuge” from water flow and predators instead of drifting down the river to be eaten by predators or buried or suffocated by silt, Miller said.
“In general, humans like to take all of the ‘debris’ out of streams and rivers, creating a biological desert,” Miller said. “The more we can provide diverse habitat, the more aquatic, amphibious and terrestrial species will flourish and improve the ecology of the river and the land-water interface.”
To float the 4,000-pound boulders into position, Drax workers created a small barge from floating pier sections, Luchsinger said.
Water in the river is too deep for excavators, Luchsinger said.
About 20 boulders will be placed upstream from where the Monterey Dam used to be. The remaining 30 boulders will be placed downstream, Luchsinger said.
Woodard said he has seen a lot of people fishing near the former dam site this summer, a year after the dam was removed.
“I hear fishing is good,” Woodard said.
The restoration project has been estimated by the city to cost $1.27 million. Nearly $920,000 of that is covered by grants from the state DNR, according to a previous report by The Gazette.
The city council voted in March 2017 to remove the Monterey Dam. The removal process began in July 2018 after years of contention between the city and vocal opponents, many of whom belonged to the Monterey Dam Association.
Cost to maintain the dam was cited by council members as a primary reason to remove it. Opponents have been concerned about the environmental impact of removing the dam and how the city managed the dam removal process.