The Mississippi could drop below flood stage at a key gauge in Vicksburg for the first time in nearly six weeks and officials said Thursday that repairs could start soon on a levee that was blown in Missouri to relieve pressure from the swollen river.

These are key milestones in the historic flood of 2011, but the slow-moving, weekslong disaster could require years of recovery and cost $1 billion in repairs to the levee system alone, officials said.

Col. Thatch Shepard, deputy commander of the U.S. Army Corps of Engineers’ Mississippi River Division, said the government will have to prioritize projects based on funding. He said the flood put unprecedented stress on a levee system that cost $13 billion to construct since 1928.

Shepard joined other corps officials Thursday on a large barge on the Mississippi River near Vicksburg, where the water has slowly retreated back toward it banks after reaching 57.1 feet — almost a foot higher than the previous record set in 1927.

Like other areas along the Mississippi, Vicksburg is drying out, but recovery will take time. About 200 houses flooded in the city alone, with more in surrounding Warren County and other low spots on the unprotected side of the levees. The flooded Mississippi also forced tributaries to flow backward, pushing water upstream for miles and flooding tens of thousands of acres in Mississippi alone.

Col. Jeff Eckstein, commander of the U.S. Army Corps of Engineers’ Vicksburg District, said the river was at 43.5 feet Thursday at Vicksburg, slightly above the 43-foot flood stage.

“The system held, did what it’s supposed to do, protected everybody behind the levees” Eckstein said.

Shepard and Eckstein said officials are now focused on repairing damages to the levees created by unprecedented water levels and flow rate.

“It’s a systems approach. We’re going to look at everything and they will be evaluated on priority of funding,” Eckstein said.

At the top of the priority list is New Madrid Floodway at Birds Point, where the levee was blown to save the town of Cairo, Ill., while sacrificing thousands of acres of farm land in Missouri.

“Believe it or not, farmers are already planting again in that floodway,” Shepard said.

Equipment and personnel were moved to the site this week, and Shepard said repairs there could cost $30 million to $90 million. The corps budget for the fiscal year is about $210 million, Shepard said, so he hopes Congress will approve supplemental funding.

Repairing the New Madrid Floodway levees is vital in the portion of the flood system that protects parts of Illinois, Kentucky, Tennessee and Missouri.

“So you have four states that have a vested interest in how those repairs go,” Shepard said.

The corps hopes to have the levees all along the river repaired before next spring’s flooding season. Shepard said he’s not sure funding will be available for the estimated $700 million to $1 billion it could cost to fix all the levees.

“We’re going to have to make some tough decisions here. Public safety will really be the No. 1 priority,” Shepard said.

Other repairs the corps hopes to make are to sandboils, where water seeped under levees and levee slides, where levees eroded when the water dropped.

Shepard said the extent of damage is still not known. The water has to go down to see what repairs will be needed at the Morganza spillway in Louisiana.

Shepard knows he’s throwing around some big dollar figures, but he said economists estimate that the levees saved $60 billion to $70 billion in property and infrastructure.

“Talk about a return on an investment for American taxpayers, that’s it” he said.