TRAVERSE CITY, Mich. (AP) — Michigan, Illinois and a federal agency have agreed on funding the next phase of an initiative to keep Asian carp out of the Great Lakes by strengthening defenses on a Chicago-area waterway, officials said Thursday.

The two states and the U.S. Army Corps of Engineers will share pre-construction engineering and design costs for the $858 million project at Brandon Road Lock and Dam near Joliet, Illinois. The structure on the Des Plaines River is a choke point between the Illinois River, which is infested with the invasive carp, and Lake Michigan.

A plan approved by the Corps in 2019 calls for installing a gantlet of technologies to deter approaching fish, including electric barriers and underwater speakers that would blast loud noises, plus an “air bubble curtain.” A specially designed “flushing lock” would wash away carp that might be floating on the water as vessels pass through.

The next step is developing design and engineering specifications, expected to take three to four years and cost about $28.8 million.

Under the new agreement, the Corps will pay $18 million and Michigan $8 million. Illinois will chip in $2.5 million and serve as the “non-federal sponsor” required for such projects.

The federal share of the design and engineering funds still needs to be provided through annual Corps work plans, said Col. Steven M. Sattinger, commander of the Corps’ district office in Rock Island, Illinois.

Both states will collaborate with the Corps as it designs the complex mechanism, which will require thousands of pages of drawings.

Extensive research is still needed for some features, which never have been built to the scale that will be required at Brandon Road, Sattinger said.

“It's not as easy as it sounds,” he said during an online news conference.

Four species of carp were imported from Asia in the 1960s and 1970s to clear algae from Deep South sewage ponds and fish farms. They escaped into the Mississippi River and have moved north into dozens of tributaries in Middle America.

Government agencies, advocacy groups and others have long debated how to prevent them from reaching the Great Lakes, where scientists say they could out-compete native species for food and habitat. The lakes region has a fishing industry valued at $7 billion.

“If Asian carp invade the Great Lakes, they would have a devastating impact on our fisheries, tourism and outdoor recreation economies, and way of life across the region," said Marc Smith, policy director for the National Wildlife Federation.

A shipping canal that forms part of the link between the Mississippi and Lake Michigan has a network of fish-repelling barriers, which the Corps says is effective but critics consider inadequate. The Brandon Road project will provide another layer of protection further downstream.

“Long in planning, we’re pleased to finally put these agreements into action, allowing us to move the project to its next steps – planning and design – and, ultimately, construction,” said Colleen Callahan, director of the Illinois Department of Natural Resources.

Once design is complete, building the system will take six to eight years, Sattinger said.

The deal between states that have sometimes quarreled over how to stop the carp is “a model of partnership that we hope to see more of in the future as we work toward a common goal of securing the health and longevity of our states’ greatest natural resource,” said Molly Flanagan, chief operating officer of the Alliance for the Great Lakes.