TOLEDO, Ohio -- The strategy most Great Lakes scientists seem to prefer to prevent Asian carp from entering Lake Michigan near Chicago would cost taxpayers $18.4 billion and take 25 years to build, according to a long-awaited Army Corps of Engineers study released Monday.
Now it's up to Congress to decide if it will give those scientists what they want.
The Toledo area and other parts of western Lake Erie in Ohio between Monroe and Sandusky -- the heart of the Great Lakes region's $7 billion fishery -- have a lot at stake with the decision, from fishing jobs to tourism opportunities.
Silver Asian carp and silver bighead carp -- the two most destructive of four fish species commonly known as Asian carp -- have encroached on Lake Michigan for years now after escaping Southern fish hatcheries flooded in 1995 by the Mississippi River.
The fish have migrated upstream against the river's current and have colonized tributary rivers including the Wabash and Illinois.
The Wabash poses a direct threat to the Maumee River -- the region's most productive for fish spawning -- through the risk that Eagle Marsh, a wetland near Fort Wayne, might flood and temporarily connect the two watersheds, providing carp a pathway through a chain-link fence.
But the most likely flash point has been in Chicago, where the Chicago River's flow was reversed a century ago to flush wastewater out of the city. As a result, Lake Michigan has been connected to the Mississippi through a series of canals and natural streams.
Disconnecting the Lake Michigan and Mississippi watersheds is a concept pushed by countless Great Lakes fishery biologists, university professors and policy experts, including the Ann Arbor-based Great Lakes Fishery Commission, founded by the United States and Canada in 1955 to combat invasive species.
The great unknown was the price.
A 2012 engineering analysis issued by the Ann Arbor-based Great Lakes Commission -- a regional board funded by the eight Great Lakes state and two Canadian provinces -- and the Chicago-based Great Lakes and St. Lawrence Cities Initiative, funded by Great Lakes-area cities, estimated the cost of watershed separation at $9.5 billion. That price, the commission noted, would be less than the cost of burying Interstate 93 through Boston.
But the corps of engineers, in its report to Congress, said separating Lake Michigan from the Mississippi would cost nearly twice as much -- $18.4 billion -- and take a quarter of a century to do.
One of the key differences in the two studies is the corps used a 500-year flood event for its proposal, whereas the consultant for the Great Lakes Commission and Great Lakes/St. Lawrence Cities Initiative used a 100-year flood. The former is more conservative, based on conditions only likely to occur, on average, once in 500 years.
Dave Wethington, the corps' project manager, said the corps believed it was more appropriate to base the design around a 500-year flood to ensure Chicago-area residents have safeguards against flooding and polluted drinking water.
He acknowledged there is a "very real possibility" the Great Lakes fishery could be changed in the 25 years it takes to complete such a project.
"Can we do it quick enough [to prevent Asian carp from colonizing the lakes]? The answer is, nobody knows," Mr. Wethington said.
The corps report, originally scheduled to be released at the end of 2015, was submitted to Congress nearly two years ahead of schedule after several Great Lakes congressmen accused the agency of dragging its feet and shepherded legislation speeding up the study's schedule.
The corps said it would meet the deadline but make no recommendations nor list engineering options in order of priority. It also considered how each strategy could help fend off a dozen other invasive fish and plants, not just Asian carp.
The report contains eight options, one of which calls for the status quo. Six call for physical barriers or construction work ranging from $7.8 billion to $18.4 billion. One calls for $68 million a year for nonconstruction measures, including public education, tougher enforcement of boating laws and use of poisons to kill carp.
Mr. Wethington said a combination of options is possible, but the corps believes none offer a sure-fire guarantee -- not even a complete hydrological separation.
Congress needed the corps' report before it could consider such a massive project, said Marc Gaden, a Great Lakes Fishery Commission spokesman.
"I feel good about the fact we can now get on with it," he said of the congressional review.
Members of Congress from the Great Lakes region had much to say about the report but did not commit themselves to any of the options.
U.S. Rep. Marcy Kaptur, D-Toledo, "has always favored hydrological separation and still does," according to Steve Fought, her communications director.
"The problem, of course, is getting the political will of Congress to support hydrological separation, because it's going to cost a lot of money," Mr. Fought said.
He said Miss Kaptur has a sense of urgency about the issue.
"To her, it's a matter of equity for Lake Erie's fishing and tourism industries," Mr. Fought said.
U.S. Sen. Debbie Stabenow, D-Michigan, who has supported a hydrological separation in the past, stopped short of embracing the $18.4 billion option in a conference call with reporters. She said, however, the most obvious choice to cross off the list is no action.
"The biggest disappointment is there are seven options here other than the status quo," she said, explaining that she had hoped for a little more direction from the corps.
U.S. Sen. Rob Portman, R-Ohio, agreed, saying he wished "the U.S. Army Corps of Engineers' report would have identified the best option for preventing the spread of invasive species to the Great Lakes."
Lake Erie, Mr. Portman said, is a backbone to Ohio's economy and helps support 100,000 jobs.
U.S. Sen. Sherrod Brown, D-Ohio, said keeping Asian carp out of the Great Lakes and the Ohio River "is about safeguarding our economy and the livelihood of thousands of Ohioans."
The corps is taking public comment on its report through March 3 and has scheduled six public meetings across the Great Lakes basin -- plus one in St. Louis -- for discussion.
Closest to the area will be meetings Jan. 16 in the Cleveland Public Library, 325 Superior Ave. NE, Cleveland, and Jan. 21 at the University of Michigan League, 911 N. University Ave., Ann Arbor. Both will run from 4 to 7 p.m.
Block News Alliance consists of the Pittsburgh Post-Gazette and The Blade of Toledo, Ohio. Tom Henry is a reporter for The Blade.