FORT WAYNE – The U.S. Army Corps of Engineers has outlined nine options for keeping invasive species from traversing Eagle Marsh to jump between the Great Lakes and Mississippi River watersheds.
The options include a concrete Berlin Wall-like structure across the marshland, a massive, $20 million pump station, building screens and creating levee-like berms.
Currently, there is no funding to pay for any of the ideas.
In late 2010, the Indiana Department of Natural Resources built a temporary fence across the marsh to prevent the migration of Asian carp, a huge, voracious fish that has invaded the Mississippi River system.
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 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.
As an environmental organization that battles invasive plants and species day in and day out at our preserves, we don’t want to help invasive species, said Betsy Yankowiak, director of preserves and programs for Little River Wetlands Project, which oversees the marsh.
Yankowiak said the options most acceptable to Little River Wetlands Project officials are H and I. Those choices tear down and then rebuild to federal standards existing berms along Graham-McCulloch Ditch, because they use structures already in place that would create the least long-term changes to the area.
They’re already in the landscape, wildlife is already used to a berm being there, so it’s not going to disrupt their traffic patterns, she said.
Yankowiak also said that while the Asian carp has gotten the most attention, there are many other invasive species that could jump basins.
Behind the Asian carp are 40 other invasive species storming up the Wabash toward the Great Lakes, she said. And there are 160 invasive species in the Great Lakes that could threaten the Mississippi basin.
The biggest priority for containment, the report says, is not the Asian carp at all, but viral hemorrhagic septicemia virus, known as VHS.
That makes many of the options useless, because they would keep out large species, such as Asian carp, but would be powerless to stop a virus when the waters mix. The wall or the berms, meanwhile, would create physical barriers to prevent the streams from ever touching.
The physical barriers have a downfall, too: Because they prevent Junk Ditch from draining into the Mississippi River basin, it could cause more flooding downstream near Ardmore Avenue.
The report is not meant to recommend any of the options; those decisions will have to be made later. In the meantime, the public is invited to comment on the report, which can be found at tinyurl.com/JGmarshplans.
Comments for the draft report will be accepted through Dec. 7. Comments may be submitted electronically at www.glmris.anl.gov or mailed to GLMRIS Focus Area 2, Summary Report Comments, 1776 Niagara St., Buffalo, NY 14207-3199.
At a glanceNine options from a new Army Corps of Engineers report to keep invasive species from moving through Eagle Marsh in southwest Fort Wayne:
Alternative A – Construct a wall across the marsh; cost: $12.8 million
Alternative B – Combination of fence and rebuilt berm; cost: $2.4 million
Alternative C – New berm and pump station near Homestead Road; cost: $20.2 million
Alternative D – Build a permeable berm with sluice gates for low-water times; cost: $8.3 million
Alternative E – Combination of fence and new berm; cost: $3.8 million
Alternative F – Screens at existing weirs; cost: $2.8 million
Alternative G – Berm and screened drop structures; cost: $4.7 million
Alternative H – Reconstruct left Graham-McCulloch Ditch berm; cost: $5.5 million
Alternative I – Reconstruct left berm, remove right berm and construct wetlands; cost: $7.7 million
To see the report, to go tinyurl.com/JGmarshplans
Source: U.S. Army Corps of Engineers