Three fundamental strategies for addressing spilled oil were: to contain it on the surface, away from the most sensitive areas, to dilute and disperse it into less sensitive areas, and to remove it from the water. The Deepwater response employed all three strategies, using a variety of techniques. While most of the oil drilled off Louisiana is a lighter crude, the leaking oil was of a heavier blend which contained asphalt-like substances. According to Ed Overton, who heads a federal chemical hazard assessment team for oil spills, this type of oil emulsifies well. Once it becomes emulsified, it no longer evaporates as quickly as regular oil, does not rinse off as easily, cannot be eaten by microbes as easily, and does not burn as well. "That type of mixture essentially removes all the best oil clean-up weapons", Overton said.
On 6 May 2010, BP began documenting the daily response efforts on its web site. While these efforts began using only BP's resources, on 28 April, Doug Suttles, chief operating officer, welcomed the US military as it joined the cleanup operation. The response increased in scale as the spill volume grew. Initially, BP employed remotely operated underwater vehicles, 700 workers, four airplanes, and 32 vessels. By 29 April 69 vessels, including skimmers, tugs, barges, and recovery vessels, were active in cleanup activities. On 4 May, the US Coast Guard estimated that 170 vessels, and nearly 7,500 personnel were participating, with an additional 2,000 volunteers assisting. On 26 May, all 125 commercial fishing boats helping in the clean up were ordered ashore after some workers began experiencing health problems. On 31 May, BP set up a call line to take cleanup suggestions which received 92,000 responses by late June, 320 of which were categorized as promising.
An oil containment boom deployed by the U.S. Navy surrounds New Harbor Island, Louisiana.
The response included deploying many miles of containment boom, whose purpose is to either corral the oil, or to block it from a marsh, mangrove, shrimp/crab/oyster ranch or other ecologically sensitive areas. Booms extend 18–48 inches (0.46–1.2 m) above and below the water surface and are effective only in relatively calm and slow-moving waters. More than 100,000 feet (30 km) of containment booms were initially deployed to protect the coast and the Mississippi River Delta. By the next day, that nearly doubled to 180,000 feet (55 km), with an additional 300,000 feet (91 km) staged or being deployed.
Some US lawmakers and local officials claimed that the booms didn't work as intended, saying there is more shoreline to protect than lengths of boom to protect it and that inexperienced operators didn't lay the boom correctly. Billy Nungesser, president of Plaquemines Parish, Louisiana, said the boom "washes up on the shore with the oil, and then we have oil in the marsh, and we have an oily boom. So we have two problems”.
Barrier island plan
On 21 May, Plaquemines Parish president Billy Nungesser publicly complained about the federal government's hindrance of local mitigation efforts. State and local officials had proposed building sand berms off the coast to catch the oil before it reached the wetlands, but the emergency permit request had not been answered for over two weeks. The following day, Nungesser complained that the plan had been vetoed, while Army Corps of Engineers officials said that the request was still under review. Gulf Coast Government officials released water through Mississippi River diversions to create an outflow of water that would keep the oil off the coast. The water from these diversions comes from the entire Mississippi watershed. Even with this approach, on 23 May, the National Oceanic and Atmospheric Administration predicted a massive landfall to the west of the Mississippi River at Port Fourchon. On 23 May, Louisiana Attorney GeneralBuddy Caldwell wrote to Lieutenant General Robert L. Van Antwerp of the US Army Corps of Engineers, stating that Louisiana had the right to dredge sand to build barrier islands to keep the oil spill from its wetlands without the Corps' approval, as the 10th Amendment to the U.S. Constitution prevents the federal government from denying a state the right to act in an emergency. He also wrote that if the Corps "persists in its illegal and ill-advised efforts" to prevent the state from building the barriers that he would advise Louisiana GovernorBobby Jindal to build the berms and challenge the Corps in court. On 3 June, BP said barrier projects ordered by Adm. Thad Allen would cost $360 million. On 16 June, Great Lakes Dredge and Dock Company under the Shaw Environmental and Infrastructure Group began constructing sand berms off the Louisiana coast.
By late October, the state of Louisiana had spent $240 million of the proposed $360 million from BP. The barrier had captured an estimated 1,000 barrels (160 m3) of oil, but critics and experts[who?] say the barrier is purely symbolic and call it "an exercise in futility" given the estimated 5,000,000 barrels (790,000 m3) of oil in the gulf and the millions of dollars and man-hours used to build the barrier. Many scientists say the remaining oil in the Gulf is far too dispersed to be blocked or captured by the sand structures. "It certainly would have no impact on the diluted oil, which is what we're talking about now," said Larry McKinney, head of the Gulf of Mexico research center at Texas A&M University. "The probability of their being effective right now is pretty low."
On 16 December, a report by a presidential commission called the berms project "underwhelmingly effective, overwhelmingly expensive" because little oil appeared on the berms. However, the commission admitted the berm might help with reversing the effects of erosion on the coast. Jindal called the report "partisan revisionist history at taxpayer expense".