The Houston Ship Channel (HSC) was partially reopened to barge traffic March 25 after a marine fuel oil spill shut down the waterway for a few days.

The U.S. Coast Guard had reported March 24 that 46 outbound and 47 inbound vessels were in the queue for transit in the Port of Houston.

The operator of the bulk carrier that collided with the barge carrying fuel oil in the HSC was on probation for a 2011 federal pollution violation.

Cleopatra Shipping Agency Ltd. operates the Summer Wind, a 585-foot Liberian flag vessel owned by Sea Galaxy Marine SA, Greg Beuerman, a spokesman for the U.S. Coast Guard Joint Information Center, said in a telephone interview with Bloomberg March 25.

Cleopatra Shipping, based in Pireas, Greece, pleaded guilty in September 2012 to violating the Act to Prevent Pollution from Ships, according to a statement from federal prosecutors in Baton Rouge, La., issued at the time. Cleopatra Shipping was ordered to pay a $300,000 fine and serve a three-year term of probation requiring implementation of an environmental compliance program.

According to the plea agreement entered at the time, Cleopatra Shipping was allowed to move for early termination of the probation after 24 months. There’s no indication from the court docket that the company has applied for that. Conditions of the probation included no further violations of federal, state or local laws and the funding of the compliance program.

In August 2011, the Stellar Wind, an ocean-going bulk carrier traveling from Spain to the U.S., discharged bilge water and other oily waste without using an oily-water separator as required by federal and international law, prosecutors said. The chief engineer didn’t record the illegal discharges as required and made false entries indicating that the separator was used.

A message left by Bloomberg March 25 with U.S. Attorney J. Walter Green, working in Louisiana’s Middle District in Baton Rouge, seeking comment wasn’t immediately returned. There was no answer at numbers listed for Cleopatra Shipping in Greece and London.

The 4,000-barrel spill occurred when a barge being towed by the vessel Miss Susan collided with the Summer Wind, causing one of the barge’s six tanks to leak fuel oil, the Coast Guard said. The Coast Guard is investigating.

The barge is owned by Kirby Inland Marine LP, which is responsible for the cleanup. The Oil Pollution Act applies even though the collision occurred in state waters, Beuerman said.

Kirby Inland Marine and Cleopatra Shipping were sued March 25 in Houston federal court by commercial and sport fishermen claiming damages from the weekend spill, which closed the HSC, the entrance to one of the nation’s busiest ports.

That lawsuit may start a protracted legal battle over who will bear ultimate financial responsibility for environmental damages, which could drag on for years.

“I think we found after the BP oil spill it’s very difficult to predict how that oil is going to behave,” Melinda Taylor, a law school lecturer at the University of Texas at Austin who specializes in environmental issues, said in a telephone interview with Bloomberg. “A lot of it depends on weather conditions, the type of oil that spilled, the weight of that oil and the constituents in that oil.”

While Kirby Inland Marine will foot the bill for the cleanup up front, the company may seek to recoup costs from other parties if they are found to be responsible for the collision, Taylor said.

“Under the Clean Water Act, the government can recoup natural resources damages,” she said. “As we found in the Exxon Valdez, and more recently in the BP case, those damages can add up really quickly.”

The spill will probably endanger migratory birds coming from Mexico, Central America and South America, said Robin Doughty, a professor in the department of geography and the environment at the University of Texas at Austin.

“Galveston Bay is one of the major sites for migratory birds in the U.S.,” he said in a telephone interview with Bloomberg. “The spill impacts the colonies that live in the area, but also others that are migrating to the site, potentially exposing who knows how many birds to the oil.”