JACKSON, Miss. -- Freight barges were idled among some 50 vessels stacked up Tuesday along a normally bustling stretch of the Mississippi River that was closed as crews worked to clean up leaking oil spilled in a weekend barge accident.
Workers have been skimming oily water around the clock near Vicksburg, Miss., since a barge carrying thousands of gallons of oil struck a railroad bridge and began leaking before dawn Sunday. The accident forced the closure of a 16-mile stretch of the lower Mississippi, a major inland corridor for vessels carrying oil, fuel, grain and other goods.
A Coast Guard spokesman, Jonathan Lally, told The Associated Press by telephone early Tuesday that 50 barges and other vessels idled as the river remained closed to traffic eight miles north and eight miles south of Vicksburg.
Lally said the Coast Guard would release an estimate of how much oil spilled later Tuesday.
"The reason why the vessels are being held is the sensitive nature of this work," Lally said. "They are concerned with safety of all those working at the site and any transit in the area could cause a wake, which wouldn't be safe for the crews there."
A tug was pushing two tank barges when the collision occurred about 1:30 a.m. Sunday, authorities said. Both barges were damaged, but only one leaked and authorities subsequently declared the bridge safe after an inspection.
Experts say the stretch of river is one of the most dangerous along the 2,500-mile-long river.
The leaking tank, which was pierced above the water line, was carrying 80,000 gallons of light crude, authorities said. The Coast Guard hasn't said how much oil was in the other tanks on the barge and the companies involved have declined to comment.
Tugs were holding the ruptured barge at the bank on the Louisiana side of the river, directly across from Vicksburg's Riverwalk and Lady Luck casinos.
Orange boom floated in the water downstream and oil was being pumped from the ruptured tank into another tank on the same barge. Another boom was set up as a second line of defense. Officials hope to eventually transfer all the oil to another barge in coming days.
Lally said some oil could be seen lapping up against one of the booms, but it was being held in place. He said the oil was being contained and there was no evidence of it washing ashore.
"We did have a Coast Guard helicopter crew fly for 60 miles up the shoreline there to see if they could spot any environmental impact and they weren't able to find anything," he said, adding a Coast Guard boat surveying 15 miles south of the site also detected nothing.
Lally said officials were awaiting a recovery plan from the spill's "responsible party" and would then have "a better estimate of when the river will be reopened."
Both of the barges involved are owned by Corpus Christi, Texas-based Third Coast Towing LLC, authorities said. A woman who answered the phone at the company Tuesday declined to comment.
Both vessels were being pushed by the tug Nature's Way Endeavor. The website for Nature's Way Marine LLC of Theodore, Ala., identifies the vessel as a 3,000-horsepower, 90-foot-long boat. It was built in 1974 and underwent a rebuild in 2011, according to the company.
The company referred calls to the Coast Guard on Tuesday.
Authorities said United States Environmental Services, an oil spill response company, was collecting oily water.
Drew Smith, a hydraulic engineer with the Army Corps of Engineers, wouldn't speculate on the specific cause of Sunday's crash, which is under investigation by the Coast Guard. But he said the Mississippi at Vicksburg is challenging for southbound vessels.
Southbound tows must travel faster than the flow of the water for their rudders to steer effectively. At Vicksburg they must negotiate a 120-degree turn on the meandering Mississippi, then straighten up to pass under the railroad bridge and the Interstate 20 bridge.
The task is made more difficult by the Yazoo River, which empties into the Mississippi north of the bridges, increasing the speed of the current.