Shippers in Vicksburg and elsewhere along the Mississippi River are prepared to have vessels navigate perilously low water into the first few months of 2013.

Months of drought have left the Mississippi near historic low levels north and south of St. Louis, where it converges with the Missouri River and a watchtower of sorts for nervous officials and industry chiefs.

“We’ll be dealing with low water until the middle of the springtime,” said Austin Golding, marketing, sales and customer service manager for Golding Barge Line, which has cut drafts on its petrochemical barges to between 7 ½ and 8 feet.

Normally, drafts — the submerged portion of barges — are 12 feet. Those depths haven’t been so deep as the river level has remained low all year.

“We’ve been running in lower drafts for the past few months and stay if we don’t get rain anytime soon,” Golding said.

Vicksburg-based Magnolia Marine and Transport Co. has cut drafts on its barges “by about 20 percent” when in tight spots on the low river, said Roger Harris, vice president of operations.

“We have to pick our spots, do smaller tows,” Harris said. “All we need is a couple of good rains up north.”

The National Weather Service in Jackson forecasts show a line of showers moving across the Lower Mississippi just south of St. Louis by late next week, with up to an inch of rain projected, meteorologist Anna Weber said. Precipitation totals along the Missouri basin couldn’t be projected for December, but maps showed it “even” for the month, Weber said.

Upriver, Cargo Carriers has shortened drafts to 7 feet headed from the Gulf of Mexico to points north of St. Louis, company president Rick Calhoun told The Associated Press. He said every foot of reduced draft means 200 tons, or 13 percent, less cargo being shipped. Cargo Carriers is the shipping arm of Minnesota-based Cargill Inc., operating 1,300 barges.

Nashville, Tenn.-based Ingram Barge, the nations’ biggest carrier on the inland U.S. waterway system, plans to cut drafts to 8 feet for barges north of Cairo, Ill., a company spokesman said.

The Coast Guard has said further restrictions on barge traffic — most notably in a 180-mile stretch between St. Louis and Cairo, Ill. — are likely if the river dips to around 9 feet, though the decision will be based on observed conditions and not the level on the gauge. The river closed intermittently twice in August near Greenville after barges ran aground.

On Monday, an 18-barge tow ran aground on a submerged sandbar on the river south of Memphis. It took 20 hours to refloat the barge, causing a backup of 12 northbound vessels and twice that headed downriver, the Coast Guard said.

The Army Corps of Engineers has turned back requests by federal lawmakers and the barge industry to release more of the Missouri River it is withholding, believing the drought-starved Mississippi River the Missouri feeds still will remain open to shipping despite mounting concerns.

Army Assistant Secretary Jo-Ellen Darcy, in a Thursday letter obtained by The Associated Press, told lawmakers from Mississippi River states she doesn’t consider it necessary to boost Missouri River flows into the Mississippi — something the politicians urgently had sought.

Darcy, a top Army Corps official, noted this week’s revised National Weather Service forecast, which showed the Mississippi’s level wasn’t falling as rapidly as expected. She also said the corps is hastening its push to rid the river of rock pinnacles south of St. Louis that endanger barges when the water level is low.

The Corps hoped to hire a contractor to blow up the rocks as early as January, a month earlier than planned. Corps spokesman Mike Petersen in St. Louis said the agency has expedited soliciting bids for the work.

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The Associated Press contributed to this report.