FARGO, N.D. (AP) — A federal judge has thrown out a complaint challenging a $2.1 billion project to divert the Red River around Fargo and Moorhead, Minnesota, that accused the U.S. Army Corps of Engineers failed to follow proper protocol when selecting the route.

The channel is designed to move water around the flood-prone Fargo metropolitan area, but would need a staging area south of the cities to store water in times of serious flooding. A group representing about 20 upstream cities and townships in North Dakota and Minnesota filed a lawsuit in August 2013 asking for a cheaper project that doesn’t flood farmland.

U.S. District Court Chief Judge John Tunheim said in a ruling released late Thursday that the Corps did not violate the law when it chose a route on the North Dakota side of the waterway over an alternative on the Minnesota side. Tunheim issued no opinion on which path is the best.

“The court’s task today is not to decide whether the Minnesota alternative is good, or the selected North Dakota route is bad,” Tunheim wrote. “The court’s role is only to evaluate whether the government’s decision-making process in declining to choose the Minnesota route was ‘arbitrary and capricious.’ It was not.”

The judge did not lift a temporary injunction that stopped construction of a ring levee around the upstream communities of Oxbow, Hickson and Bakke. That will be in place until the Minnesota Department of Natural Resources completes its environmental review.

Gerald Von Korff, the attorney representing the Richland/Wilkin Joint Powers Authority that filed the complaint, said the judge’s decision to hold the injunction is good for his clients.

“The major difference between Minnesota’s environmental law and the federal is that the federal agency can authorize a project even if it is a bad one,” Von Korff said. “Minnesota’s permitting standards are drastically different. Minnesota cannot approve a project when there is a less impactful feasible alternative.”

Robert Cattanach, attorney for the Fargo-Moorhead Diversion Authority, said the judge’s decision “convincingly rejected every single legal argument” by the upstream opponents. He said he expected the final two complaints in state court to be resolved within the next month when the Minnesota DNR releases its findings.

“Virtually all legal obstacles standing in the way for permanent flood control for the Fargo-Moorhead region have now been eliminated,” Cattanach told The Associated Press.

Minnesota Gov. Mark Dayton has accused the authority of ramming the project down his state’s throat before the environmental impacts can be assessed.

The Fargo-Moorhead area dealt with three straight years of high water beginning with a record crest in 2009 that destroyed about 100 structures and led to a massive sandbagging effort to save the city. Fargo last experienced significant flooding in 2013.

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