CORALVILLE — Completing one of the last major flood-mitigation projects in Coralville will take some muscle.
Make that mussel.
Before the city can get started in earnest on an $11.7 million project that includes elevating a portion of the Cedar Rapids and Iowa City Railroad, mussels that are in the Iowa River near the tracks must be relocated or else they could be killed by the construction work.
The mussels, which are shellfish, are found mostly near the western bank of the river from the Iowa River Power Restaurant south to where Clear Creek joins the river, said Dan Holderness, Coralville’s city engineer.
Some of the mussels are endangered species. The U.S. Fish and Wildlife Service and the Iowa Department of Natural Resources required the relocation, Holderness said.
A crew from Ecological Specialists Inc., out of the St. Louis area, was moving the mussels last week and expects to wrap up the work this week. The city will pay the company up to $99,800.
Eric Belt is Ecological Specialists’ senior malacologist, which is someone who studies mollusks. He said their preliminary work found more than 10 species and an estimated 3,000 mussels in the area affected by the construction.
They’ll try to move as many as possible, with most making a short trip to the other side of the river to a known mussel bed. If there are too many, some will be taken to a bed just below the Coralville Lake dam, Belt said.
Mussels do not like to be warm or dry, he said. Those moved to the east bank are carried in mesh bags in the water while Belt and his colleagues cross by canoe. If any need to go up by the dam, they’ll be kept in water-filled containers.
Among the mussel species at the Coralville site are the Higgins eye pearly mussel, which is on the federal endangered species list, and the pistolgrip and yellow sandshell, both classified threatened and endangered in Iowa.
Belt was especially impressed with the pistolgrip population, saying they found juveniles and it was obvious adults had been reproducing.
“I’ve been doing this for 12 years and I’ve never seen so many pistolgrips in one location,” he said. “Usually they’re very rare.”
Pistolgrip mussels found by Iowa City’s Park Road bridge had to be relocated in 2010, also because of a project resulting from the historic 2008 flood.
Belt said mussels are a good “indicator species,” giving insight into things like water quality and the ecology of a river. They also clear the water a little and provide stability to the material at the bottom of a river, he said, describing them as being like living rocks.
The CRANDIC project includes a flood wall with a walkway on top outside of the Iowa River Power Restaurant.
The city initially thought the impact on the mussel area would be minimal. But then the railroad insisted that a new rail bridge over Clear Creek be built out of concern that the original plan of swapping in a new bridge on the existing alignment would disrupt rail traffic for too long, Holderness said.
That and regulations related to a nearby MidAmerican Energy substation pushed the trail farther out and increased the effect on the mussels, he said. Belt said the mussels could be crushed or smothered if they were not moved.
Holderness said the goal is to have the flood-mitigation elements of the project finished in 2013, with landscaping work the following year.
The CRANDIC project runs from near the Iowa River Power Restaurant on First Avenue to Rocky Shore Drive, a stretch that saw serious flooding in 2008.