FORT WAYNE – Federal officials have narrowed their list of options for preventing Asian carp from reaching the Great Lakes through Eagle Marsh from nine to two.
The U.S. Army Corps of Engineers announced Thursday that it had decided to study the last two of the nine options it presented in November.
Fort Wayne sits along a continental divide: The eastern half of Eagle Marsh, on the city’s southwest side, drains into the Great Lakes by way of Junk Ditch, the St. Marys River and the Maumee River. The western half of the marsh drains into the Mississippi River by way of the Graham-McCulloch Ditch, the Little River, the Wabash River and the Ohio River.
When there are floods in Fort Wayne, Junk Ditch can flow backward, flooding overland through Eagle Marsh and into the Graham-McCulloch Ditch, allowing species to move from one basin to the other, including Asian carp, a huge, voracious fish that has invaded the Mississippi River system.
To prevent this, the Indiana Department of Natural Resources built a temporary fence across the marsh in 2010.
The Corps, meanwhile, was investigating options ranging from a $2.8 million plan to just add screens at existing weirs to a $20.2 million plan to build a huge berm and pump station near Homestead Road.
The plans still on the table include reconstructing an existing berm along the Graham-McCulloch Ditch at a cost of $5.5 million, and a similar, but more ambitious plan that would reconstruct the berm, remove another berm and construct wetlands. That plan would cost $7.7 million.
None of the plans is ideal, said Betsy Yankowiak, director of preserves and programs for the Little River Wetlands Project, which owns and oversees Eagle Marsh nature preserve, but they’re better than the alternative of invasive species using the marsh as a highway back and forth between watersheds.
“Alternatives H and I were preferable, but obviously we’re not looking forward to seeing our nature preserve becoming a construction zone,” Yankowiak said. “We’re just going to have to hold our breath and wait for it to be over.”
She points out that the berm is preferable in other ways, too: Only a physical barrier preventing the two waters from ever touching will prevent the biggest invasive threat, which is viral hemorrhagic septicemia virus, known as VHS. Fences and screens may prevent fish getting through, but not a virus.
Yankowiak said the biggest drawback to the plan, if it is built, is that it will take up to five years for native plants and animals to re-establish themselves in the construction zone.