Last month, the Corps released an array of proposals for building barricades between those two vast watersheds where they meet on the southwest side of Fort Wayne. When floods inundate the area, the waters of those watersheds can meet when the Little River, a tributary of the Wabash River, and the St. Marys River and the Junk Ditch flood.
The concern is that invasive species, such as Asian carp and an aquatic virus that attacks many fish species, could spread from the Mississippi's tributaries to the waters that eventually flow into the Great Lakes.
The Army Corps brought those plans to a public meeting Tuesday at the main Allen County Public Library downtown, where more than 50 people gathered to learn more about them. About a dozen people commented during the two-hour meeting.
Three plans were rated as highly effective by the Corps.
One would build a concrete-faced wall up to 8 feet high across the marsh, at a cost of $12.8 million. The other two highly rated plans would repair and improve earthen berms around the Graham-McCulloch Ditch in the marsh, at costs of $5.5 million or $7.7 million.
Betsy Yankowiak, executive director of the Little River Wetlands Project, said she's worried about the impact of the $12.8 million wall. “Even though it is effective, it could be very disruptive,” she said. Instead, she supports one of the cheaper alternatives that would build on existing features around the ditch.
Dan Wire, who described himself as a “river activist,” asked the Corps representatives whether they had analyzed the impact of these proposals on flood levels elsewhere along the city's rivers.
Ken Lamkin, a hydrologist and hydraulic engineer working on the plans, said that he's taken only a preliminary look at impact on flood levels from the plans. “There are some concerns…there could be some impact in the upper Junk Ditch area.”
Three varieties of Asian carp, five other species of fish, plus a virus and an aquatic parasite that both afflict fish, are rated by the Corps as the most threatening “aquatic nuisance species.”
Eagle Marsh became the focus of the Corps' intense scrutiny and design-brainstorming because a team built from several federal agencies, as well as agencies from several states, identified Eagle Marsh as the most likely pathway for species migration between the basins among 31 potential pathways studied. An electric barrier already is in place in the Illinois River near Chicago, blocking the spread of the Asian carp into Lake Michigan.
You can find the entire report on alternatives developed by the U.S. Army Corps of Engineers for blocking the spread of invasive species through Eagle Marsh at glmris.anl.gov/ The Corps will accept public comment on the report through mid-January.