Initial explosion on Deepwater Horizon exploration rig kills 11 people. (1)
Second explosion sinks rig.
BP starts drilling first intercept relief well.
BP lowers containment dome over leaking wellhead, but methane hydrate crystals clog tube and the attempt fails. (2)
Research vessel Pelican finds data that suggest a giant underwater oil plume.
EPA approves subsurface use of dispersants.
BP inserts tube into riser to siphon off a small part of leaking oil and gas.
Drilling of a second relief well begins. (3)
Order to restructure Minerals Management Service is signed.
EPA directs BP to find less toxic and more effective dispersants.
EPA calls for reduction in dispersant use and says it will look for an alternative.
U.S. Geological Survey estimates leak to be 17 million to 39 million gal, making it the worst oil spill in U.S. history; Obama announces freeze on new exploratory drilling activities; and MMS head S. Elizabeth Birnbaum resigns. (4)
Attempt to plug well with drilling mud fails.
BP cuts pipe from well, lowers containment cap onto it, and begins to funnel oil. (5)