The United States has completed a wall to keep out invaders, and they have built it near the country's biggest waterway.
The first-ever fish wall marks the latest tactic against invasive Asian carp and a victory for the complex partnership of federal, state, and local officials working to protect the Great Lakes ecosystem.
The wall – known as the Eagle Marsh berm and located in in Fort Wayne, Ind. – is nearly two miles long and averages 7.5 feet in height, Brian Francisco reported for the Fort Wayne Journal-Gazette. It replaced a temporary chain-link fence with the same purpose: preventing the invasive Asian carp from swimming through Indiana's rivers to damage the rich fisheries and diverse ecosystems of the Great Lakes.
“It was kind of a back door to Lake Erie," says Betsy Yankowiak, director at Little River Wetlands Project, which co-owns the marsh, in a phone interview with The Christian Science Monitor. "Everyone was focused on Chicago."
Wildlife officials identified Eagle Marsh as the second-most likely waterway for Asian carp to enter the Great Lakes in 2010 and immediately began surveying the area for solutions. They decided in December 2013 that an earthen berm could stop the area's two water systems from mixing during flooding while requiring minimal long-term maintenance, says Ms. Yankowiak.
Bringing together the stakeholders was a big job, involving at least nine different agencies at the federal, state, and local level, plus a power company, gas company, and a local conservation non-profit.
“We had lots of things to cover: We had wetlands in the way, we had affected utilities, we had right-of-way roads, we had, ‘Where are we going to find all of that dirt?’ ” explained Duane Riethman, an area engineer for the US Department of Agriculture’s Natural Resources Conservation Service, reported the Journal Gazette.
All the soil for the berm came from the marsh itself because Little River Wetlands, where the berm was built, focuses on stopping the spread of invasive plants. As a further preventative measure, Ms. Yankowiak or the project manager visually inspected the construction equipment for mud each time work began.
Midwestern wildlife officials, the US Army Corps of Engineers, and the US Congress have all taken significant measures to keep the carp downriver from the Great Lakes. The fish were brought to Arkansas in the 1970s to clean algae from fish farms, but they proliferated throughout the Mississippi River, reaching up to 7 feet in length, The Christian Science Monitor reported. They compete with native fish for food and sometimes fling themselves out of the water, striking boaters on the river.
The berm will be the first wall used against Asian carp, Tim Eder of the Great Lakes Restoration Commission told The Christian Science Monitor. The wall is a preventative step, as the invasive fish had not yet reached the marsh, and it places a barrier in the second-most worrisome crossing point between the Mississippi River system and the rivers that feed the Great Lakes. The area of top priority remains the Illinois River near Chicago, where the connecting waterways present "a much more active threat," Eder says.
The barrier of last resort in that waterway is an electric fence. The US Army Corps of Engineers are working on a new technology, a "lock and dam" system that would permit water to pass through the channel but keep invasive species from swimming through. The project is ongoing; for now, federal subsidies support efforts to net and catch the carp, and they are used for fertilizer.
Yankowiak hopes the ecosystems will someday be completely restored, and such walls would no longer be needed.
"My dream is that one day we can tear down this berm,” she says with a laugh.