After several months of back and forth, officials announced Monday that Illinois had signed a partnership agreement that will allow construction of the $1.15 billion Brandon Road Interbasin Project to begin in early 2025 with significant federal funding.

The effort, decades in the making, will become the last, multi-pronged line of defense to stop invasive silver and bighead carp from making it into Lake Michigan, where they pose a threat to Great Lakes ecosystems and billion-dollar fishing and boating industries.

In the last few weeks, the office of Gov. J.B. Pritzker and the state of Illinois reviewed final drafts and wrapped up negotiations to reach a final agreement that “balanced the need to preserve the Great Lakes ecosystem with the responsibility to carefully steward taxpayer dollars,” according to a news release.

The announcement comes as experts and advocates expressed concerns that $274 million in federal funds would be lost if the agreement wasn’t signed soon, and that construction workers wouldn’t be able to take advantage of an upcoming scheduled closure at Lockport Lock near Brandon Road in Joliet.

Any more delays, they said, could have resulted in irreversible disaster if carp continued upstream in Illinois waterways and breached past electric barriers in Romeoville. If the agreement wasn’t signed, the U.S. Army Corps of Engineers’ Rock Island District — which oversees the project — wouldn’t have been able to continue allocating resources to pre-construction engineering and design.

“Protecting the Great Lakes has always been and will always be a priority for the State of Illinois and after many years of this project eluding multiple administrations, I am thrilled to see it move forward,” Pritzker said in a news release Monday. “Protecting the Great Lakes is not an undertaking that any one state or city can tackle alone, and I’m thrilled that we were able to forge a path that protects both the Great Lakes and ensures Illinois taxpayers do not shoulder a disproportionate share of the burden.”

The project has been awaiting approval from Illinois for a year, after the Michigan legislature authorized $64 million in June 2023 to help finance it. Those funds, plus $50 million from Illinois will account for the project’s required $114 million non-federal cost share.

“Complex agreements like this don’t happen in a vacuum, nor do they happen quickly,” said Natalie Phelps Finnie, director of the Illinois Department of Natural Resources. “A tremendous amount of effort over many months went into hammering out the details of this agreement. I’m thrilled this consequential project will now be able to move forward.”

In a mid-June virtual news conference, where a group of local politicians, stakeholders and experts gathered to ask the governor to take swift action, Executive Director Jennifer Walling of the Illinois Environmental Council said approving the project was an opportunity for Pritzker to secure his legacy as a “champion” of the Great Lakes and “critical interstate partner” to Michigan.

U.S. Sens. Dick Durbin and Tammy Duckworth, who have supported the project and helped secure federal funding, urged Pritzker to authorize the project in a June 25 letter, where they acknowledged his concerns about Illinois taking on too much financial responsibility. The two senators and U.S. Rep. Mike Quigley applauded Monday’s announcement in a news release.