Corps study underway to stop invasive species migration

Published Dec. 15, 2010

In early November, an Army Corps of Engineers (USACE) Louisville District project team conducted an extensive site visit at a potential pathway for invasive aquatic species migration, including the bighead and white Asian carp.

The area, near Fort Wayne, Ind., lies where the Wabash River drainage basin—where all waters ultimately end up in the Mississippi River—meets the drainage basin of the Maumee River, a tributary to Lake Erie. Because a flood event could potentially cause waters from nearby streams to comingle, the invasive Asian carp species could migrate from the Wabash River, where they have already been identified, into the Maumee River where they could potentially reach the Great Lakes.

"Our main goal is to hydraulically disconnect the two basins," said Gerard Edelen, project manager. "We want to start identifying options that would stop as many species as possible from migrating between the basins and, at a minimum, stop the Asian carp."

Invasive species can disrupt ecosystems and be detrimental to indigenous species, according to Mike Turner, chief, environmental resources. Asian carp, in particular, are filter feeders that—by disrupting the food chain for native species—pose an economic threat to the commercial fishing industry.

In an effort to stop the spread of the invasive carp, the project team began the Fort Wayne Wabash-Maumee Basin Connect Feasibility Study that will identify possible alternatives for disconnecting the basins and ultimately recommend a solution. Alternatives could include structural or nonstructural, pre-existing or new or enhanced construction.

At the site near Fort Wayne, the area of main concern is the Junk Ditch pathway near the Eagle Marsh wetland. Less than one mile of flat land in Eagle Marsh separates the Graham McCullough Ditch in the Wabash Basin and the Junk Ditch in the Maumee Basin. A high-water event could flood the marsh, allowing opportunity for passage of carp from the Wabash Basin to the Maumee Basin.

The Indiana Department of Natural Resources (IDNR) has erected a chain-link fence barrier in the Little River Wetlands area that would stop the migration of adult Asian carp, but the fence is viewed as temporary and does not provide a long-term solution.

During the November site visit, the feasibility team from USACE Louisville met with representatives from IDNR, the Little River Wetlands Project and the Natural Resources Conservation Service to discuss project possibilities as well as potential setbacks. The USACE team, which consisted of engineering, hydrology, real estate, environmental planning and geology specialists, visited numerous sites in the area including the temporary fence barrier and a rock quarry.

"We want to come up with the most beneficial and least intrusive solution," said Turner.

The study is part of the Great Lakes Mississippi River Interbasin Study (GLMRIS) to explore options and technologies that could be applied to prevent the transfer of aquatic nuisance species (ANS) between the Great Lakes and Mississippi River basins through aquatic pathways. According to the GLMRIS Other Pathways Preliminary Risk Characterization report, Eagle Marsh is at the top of the list of 18 "other aquatic pathways" identified as posing a significant risk for the potential interbasin transfer of ANS.

The feasibility study is authorized and appropriated under the Water Resources Development Act through the Environmental Protection Agency and is fully funded through the Louisville District. However, once a solution is identified, construction will be cost-shared with a yet-to-be-identified local sponsor. The feasibility study will likely be complete in Sept. 2011.