CHICAGO  Asian carp, the voracious, nonnative fish whose arrival near Lake Michigan is threatening to cause havoc in the Great Lakes, are now setting off strife on land as well.  In an urgent effort to close down Chicago-area passages that could allow the unwanted fish to reach Lake Michigan, the State of Michigan is suing the State of Illinois and other entities that govern the waterways here. Minnesota, Ohio and Wisconsin have filed documents in recent days supporting Michigan’s move, and Indiana says it will soon do the same.  The new rift between these Midwestern states, which would reopen a nearly century-old legal case in the United States Supreme Court over Great Lakes waters, comes at a particularly sensitive moment  just as the numerous entities with interests in the Great Lakes had united in what lakes advocates consider some of their most significant progress in decades.  In 2008, the eight states that touch the Great Lakes helped push through a federal-state compact that bars diversion of water from the lakes unless all of the states (and the Canadian provinces involved) agree. That Great Lakes Compact, which was years in the making, at last calmed fears that other water-starved regions might tap into the lakes, which make up 20 percent of the world’s freshwater.  And this fall, the federal government approved what many saw as the first step in a major restoration for the lakes, long sought in these states.  Some $475 million was designated to clean up pollution, protect habitat and fight invasive species in the Great Lakes.  “Years ago, we realized that this region of the country needed to do a much better job of speaking with one voice or we would not be heard in Washington,” said David A. Ullrich, executive director of the Great Lakes and St. Lawrence Cities Initiative, one of several alliances that formed in recent years around the notion that those with Great Lakes interests needed to work together if they hoped to draw the support and attention captured, say, by the Florida Everglades.  Of the Asian carp threat and the legal sparring suddenly brewing between the states, Mr. Ullrich, whose group of 70 lakes mayors includes Richard M. Daley of Chicago, a Democrat, said, “It’s a very serious issue, and I think we are going to need to figure out a way to come together as a region.”  For years, leaders in the region worried about Asian bighead and silver carp  large, imported fish that can take over an ecosystem by consuming the food supply of other fish and that were known to be making their way north up the Mississippi River. But the efforts took on a new urgency in November, when the authorities reported finding genetic evidence of the carp within about six miles of Lake Michigan, in the Chicago-area waterway system that links the Mississippi to the Great Lakes.  As lake advocates called on leaders to close locks in the waterway system in an emergency effort to block the fish, representatives from the office of Mike Cox, the attorney general of Michigan, said he had reached out to leaders on the other side of the lake, in Illinois, but got no response.  Mr. Cox, a Republican who is running for governor of Michigan this year, said hundreds of thousands of jobs in his state depended on Lake Michigan, and in December he filed a lawsuit. “This is an environmental and economic emergency,” Nick De Leeuw, a spokesman for Mr. Cox, said of the potential damage the carp could inflict throughout the lakes. “It’s almost like a bad science fiction movie.”  In his legal filings, Mr. Cox called for an injunction to close locks immediately, but he is also seeking, ultimately, to separate the Mississippi River system from the Great Lakes entirely.  More than a century ago, a canal was built linking the two waterways. Barges travel between the two, and over the years, the design helped carry sewage away from Chicago and Lake Michigan as part of an engineering feat that reversed the flow of the Chicago River.  The Michigan lawsuit would reopen a Supreme Court case from the 1920s (which was later modified repeatedly) in which neighboring states complained that Illinois’s diversion of water away from the lake was wrong.  The suit leaves Illinois leaders in an awkward spot: though many of them have expressed horror at the thought of Asian carp taking over Lake Michigan, a closing of locks could also cause damage for a barge industry here. And permanent separation of the two waterways might also require changes to the Chicago area’s wastewater infrastructure.  A spokeswoman for Gov. Patrick J. Quinn of Illinois, a Democrat who is up for election this year, said he believed that “everything should be looked at in a careful and studied way.”  And Suzanne Malec-McKenna, the commissioner of Mr. Daley’s Department of Environment, said, “While we recognize that Asian carp pose a significant threat to the Great Lakes, shutting down the waterway system in Northeastern Illinois before fully understanding the impact it would have on the movement of people, goods and storm water is a shortsighted answer to a complex problem.”  Left uncertain is what so much turmoil over the carp might do to the broader efforts at cooperation on the lakes, or whether it might damage relations just as the region tries to figure out how best to spend the hundreds of millions of dollars in restoration money.  Notwithstanding this lawsuit, said David Naftzger, executive director of the Council of Great Lakes Governors (including Mr. Quinn and the governors whose states have signed on with Michigan to close the locks), there have been long efforts to work together in the region to fight invasive species, even these carp.  “That will continue,” Mr. Naftzger said, pointing out that it is attorneys general, not governors, who would be handling any legal back-and-forth. “This doesn’t mean other elements of the state governments won’t persevere to find common ground.”  All that being said, Mr. Naftzger added, if some solution to the carp problem cannot be found, all sorts of progress could eventually be at risk.
A nonnative fish that consumes the food of other, native fish is unwanted in Michigan, and the state is suing to have waterways shut down.