Goal is to keep Asian carp out of the Maumee
Fort Wayne, Ind. — The $50 million federal plan released recently for keeping Asian carp out of the Great Lakes did include measures to prevent the fish from jumping the continental divide from the Wabash River system over to the Lake Erie basin via the Maumee River.
Late last year, the U.S. Army Corps of Engineers released a report outlining the situation at Eagle Marsh in northeast Indiana and presented nine options to prevent the carp from jumping basins.
The Corps have rated Eagle Marsh a medium risk for Asian carp to gain entry to the Great Lakes and the second highest risk site behind only the Chicago area waterway system.
The Army Corps left the decision of how to proceed to a group of stakeholders led by the Indiana DNR and the Little River Wetlands Project, joint owners of the 716-acre Eagle Marsh.
As outlined by the plan, titled “Asian Carp Control Strategy Framework,” the stakeholders chose to rebuild an existing, but eroding, berm in a couple of phases that will prevent flooding of nearby property.
“That will create complete separation in the shortest amount of time,” said Phil Bloom, Indiana DNR’s communications director.
Building a concrete wall on Eagle Marsh was preferred by some in Lake Erie’s charter fishing ranks because it was deemed to be the most effective of the options.
But that would have taken a lot more time to implement at Eagle Marsh, Bloom said, since studying potential flooding of nearby property and then mitigation was far more complicated.
Still, rebuilding the berm was also rated with a high probability of preventing Asian carp from crossing over to Lake Erie’s watershed.
The Little River Wetlands Project, a non-profit that took over the marsh in 2005, had opposed the concrete wall option since it would have come at the expense of a marsh it has sunk money and labor, including tedious work to remove invasive plants, into to restore.
“We’ve put a lot of effort into Eagle Marsh,” said Little River’s Betsy Yankowiak. “We want to protect from Asian carp but at the least amount of disruption to the marsh. It’s unfortunate that Eagle Marsh is in the middle of this problem, but it is a problem, and Eagle Marsh is the site for a solution.”
In 2010, the Indiana DNR constructed a chain link fence across a section of the marsh to serve as a barrier to adult Asian carp, namely bighead and silver carp, when the site was determined by the Corps as a potential pathway for the fish to enter the Great Lakes.
Although the Wabash and Maumee rivers drain in different directions and are not connected during normal conditions, their waters can connect under certain flood conditions.
The Eagle Marsh wetlands extend over the divide into two particular drainage ditches, McCulloch Ditch, which drains west into the Little River and ultimately Wabash River near Huntington, and Junk Ditch, which drains northeast into the St. Marys River and ultimately the Maumee River.
The marsh acts as an emergency flood valve when the St. Marys reaches flood stage, preventing flooding in Fort Wayne. Building the concrete wall could have taken as many as 15 years to be completed, since affected property nearby would first have to be mitigated, Bloom said.
The potential for flooding nearby property owners still has to be dealt with in rebuilding one of the walls of the V-shaped berm.
The first phase, estimated at a cost of $3 million, would shore up an existing but failing berm wall along with a spillway elevation that is low enough that it wouldn’t affect nearby properties and high enough to provide watershed separation for up to the 25-year flood (a recurrence interval based on historical rainfall and stream stage data). The existing fence would remain in place.
Construction could start next year, Yankowiak said.
The second phase would elevate the spillway to two feet above the 100-year flood level after the Corps completes its study of off-site impacts and any affected properties are mitigated. Upon completion, the chain link fence could be removed.
But even going two feet above the 100-year flood leaves those with interest in Lake Erie’s fishery uneasy.
Western Basin charter captain Paul Pacholski, vice president of the Lake Erie Charter Boat Association, said he could understand why the Little River group wouldn’t want its hard work and effort to go to waste, but he has doubts about the proposed berm.
“I’m not sure how comforted I am by a berm that’s only two feet above the 100-year flood line, especially in the days of climate change,” Pacholski said. “In 2011, we have three of those floods (in Ohio) in one month.”
Asian carp are capable of jumping 10 feet.
Yankowiak was not sure what the recurrence interval was of a flood earlier this spring that caused damage to the berm in two places.
Thankfully, Asian carp, while established on the lower and middle portions of the Wabash, which has the longest stretch of free-flowing river (at about 400 miles) east of the Mississippi River, have not become established in the upper reaches of the river.