CAPE GIRARDEAU, Mo. — A federal judge on Friday gave the Army Corps of Engineers the go-ahead to break a Mississippi River levee and flood Missouri farmland if the agency deems it necessary to spare a flood-threatened Illinois town upstream.

A day after hearing five hours of testimony over Missouri’s bid to block any intentional levee break, U.S. District Judge Stephen Limbaugh Jr. found the corps’ plan to breach the Birds Point levee appropriate to ensure navigation and flood-control along the still-rising Mississippi.

“This court finds that the corps is committed to implementing the (floodway) plan ‘only as absolutely essential to provide the authorized protection to all citizens,'” Limbaugh said in his ruling. “Furthermore, this court finds that no aspect of the corps’ response to these historic floods suggests arbitrary or capricious decision-making is occurring.”

The corps has proposed using explosives to blow a 2-mile-wide hole through the levee in southeast Missouri’s Mississippi County, arguably to ease waters rising around the upstream town of Cairo, Ill., near the confluence of the Mississippi and Ohio rivers.

Illinois, Kentucky and Tennessee all want the corps to move forward with the plan. Missouri had sought a temporary restraining order to block the detonation, and Attorney General Chris Koster immediately appealed Limbaugh’s ruling to the Eighth U.S. Circuit Court of Appeals in St. Louis.

Limbaugh already had voiced reluctance to get involved in the dispute, noting a 1984 federal appeals court ruling found that Congress had given the corps broad discretion in operating floodways such as the southeastern Missouri one — and that challenges of that authority were “largely unreviewable.”

The corps halted its preparation for the levee break Thursday, saying it needed until the weekend to assess whether a sustained crest of the Ohio at Cairo would demand the extraordinary step.

The river’s crest at the Cairo flood wall could reach 60.5 feet — a foot above its record high — as early as Sunday and stay that level before slowly retreating by Tuesday, according to the National Weather Service’ office in Paducah, Ky. Cairo’s wall protects the town up to 64 feet, but there’s concern the lingering crest could put extra pressure on it and earthen levees protecting other parts of the city.

Jim Pogue, the region’s Army Corps spokesman, said the agency remained “in a wait-and-see stage” Friday, with twin barges loaded with explosives still docked six hours downriver from the Bird’s Point levee.

“We’re hoping we can get a handle on this and sincerely hope we won’t have to operate the floodway,” he said. “Our intent is to make sure that if we have to move on to the next step (and breach the levee), everyone would have at least 24 hours’ notice.

“We’re just in a holding pattern right now. I can’t speculate on when something might happen.”

John McManus, an assistant Missouri attorney general, had argued in court Thursday that the break would unleash a torrent of water that would carve a channel through prime farmland, flood about 90 homes and displace 200 people. The rush of water also stood to cause an environmental catastrophe, sweeping away everything from fertilizer to diesel fuel, propane tanks, pesticides and other toxins, McManus and some of the four witnesses who testified for the state suggested.

Attorneys for the corps and the state of Illinois countered that the farmers already have land that’s flooded and have been given ample notice to clear their properties of anything toxic. The state of Illinois and the town of Cairo argue the well-being of Cairo’s 2,800 residents outweighs farmland that would be swallowed up by the rush.

Cairo Mayor Judson Childs welcomed Limbaugh’s ruling Friday, but issued another call for the struggling city’s residents to voluntarily clear out as earthen levees safeguarding it continued to show seepage. At least a couple hundred residents heeded Child’s urging to leave earlier this week.

Limbaugh’s decision “was the proper thing to do. You just don’t select land over people’s lives,” Childs said after the ruling, for which he said he was “very appreciative, and the people of Cairo are grateful for it.”