A fleet of oil-retrieving skimmers and other vessels, as well as close to 400 people, were working Monday in parts of the Houston Ship Channel to contain up to 400 bbl (168,000 gallons) of heavy oil that spilled following a collision Saturday between an oil barge and cargo ship. The ship channel, one of the world’s busiest waterways to move petrochemicals, could be closed partially to import and export traffic for a week or more.

The U.S. Coast Guard (USCG) on Monday afternoon was working to reopen a portion of the shipping lanes. The estimated economic impact of closing the Houston Ship Channel is $330 million/day, according to the Port Authority of Houston.

Last year about 2.15 million b/d of fuel products, including gasoline and diesel, were exported via the Houston Ship Channel from the Gulf Coast, while 3.76 million b/d of crude were imported, according to the Energy Information Administration. When imports are delayed, refiners may use more domestic crude from pipelines. However, the Gulf Coast refiners export around 11% of the nation’s fueling capacity.

Refiners offered few details on the impacts to their operations. ExxonMobil Corp. had reduced rates at its 560,500 b/d refinery in Baytown, but no other information was revealed. Marathon Petroleum Corp., Royal Dutch Shell plc and Valero Energy Corp. are among the biggest refiners in the region. Valero’s refineries near Houston and in Texas City have combined capacity of more than 300,000 b/d.

As of Monday afternoon, 93 vessels were waiting to move through the channel, with 56 outbound and 37 inbound, the USCG stated. The lanes are closed from north of Texas City to the entrance at the Bolivar Peninsula. According to USCG data, six collisions occurred last year closing the ship channel a combined 26 hours, versus 5.5 hours in 2012 and 157.2 hours in 2011. 

Heavy oil continued to wash ashore Monday afternoon.

“This is a significant spill,” said USCG Capt. Brian Penoyer, commander of the Houston-Galveston regional office. To complete the cleanup “will take quite a bit of time, given the complexity of the vessels and a very busy waterway.”

The USCG, the National Transportation Safety Board and the Texas Land Office are investigating.

According to authorities, Houston-based Kirby Inland Marine Corp.’s Miss Susan was towing a barge carrying close to one million bbl of heavy crude when it collided in heavy fog just after noon on Saturday with Summer Wind, a 585-foot cargo ship. The capital of the Summer Wind, which was carrying rice, reported the incident.

The Kirby Corp. barge was being towed to the Bolivar Peninsula from Galveston. Six crew members on the tow vessel were injured; two people were transported to the hospital after coming into contact with hydrogen sulfide, officials said.

Kirby Inland Executive Vice President Jim Guidry said the company was “very concerned. We’re focused on cleaning up” and would take responsibility for the costs. Earlier this month Kirby Inland announced that this year it plans to add 830,000 bbl of inland tank barge capacity to its Houston operations to carry growing U.S. unconventional oil production.

The damaged barge’s oil load was emptied Sunday, with contents transferred to other vessels to prevent more spills from a hole in one of the tanks. The barge then was refloated and moved to a different position near the site of the collision. Environmental crews, boats and oil booms were being deployed from the Texas City Dike, which juts into Galveston Bay.

Some cleanup crews were being deployed from the Texas City Dike, which juts five miles into Galveston Bay.

According to the Texas City Office of Emergency Management (OEM), the spill could have been far worse because the barge was holding close to one million gallons of oil at the time of the collision. An OEM spokesman said there was a “reasonable amount of oil” in the water.

Warnings to mariners were in place for Galveston Bay, the third largest sailboat harbor in the country. There also is a fragile shorebird habitat on both sides of the Ship Channel. The Houston Audubon Society said the Bolivar Flats Shorebird Sanctuary attracts up to 70,000 shorebirds at this time of the year and peak shorebird migration season is approaching.

Officials also closed bay area parks and asked people not to fish in the popular areas along the flats, and to dispose of any fish that had been caught. Ferry services between Galveston and the Port of Bolivar also were suspended, but partial service could be restored soon, the USCG said. Two Carnival Corp. cruise ships were allowed to enter and dock in Galveston on Sunday and Monday “to minimize inconvenience to the thousands of passengers aboard and limit economic impacts from the spill,” according to the USCG.