When did the gulf oil spill happen?

The gulf oil spill started on the 20th April 2010.

approximately 11:00 pm.
april 12 see link
The most notable oil spill of 2010 was the BP Gulf of Mexico oil spill, occurring on April 20.

Other Oil spills of 2010 include:

• Yellow River oil spill in China, started on 30 December 2009 and continued in 2010
• Port Arthur oil spill in Texas, started 23 January
• Great Barrier Reef oil spill off Australia, started 3 April
• ExxonMobil oil spill in Nigeria, ruptured pipeline on 1 May.
• Trans-Alaska Pipeline spill, near Anchorage, Alaska, 25 May.
• MT Bulunga Kelana 3, Malaysia, started 25 May.
• Red Sea oil spill in Egypt, started on 15 June
• Red Butte Creek oil spill, Salt Lake City, Utah, USA, 11 June.
• Xingang Port oil spill in China, Started on 16July.
• Talmadge Creek, Kalamazoo, Michigan on 26July.
• Barataria Bay, Louisiana, 50 miles south of New Orleans. 27 July to present day.
• Mumbai Oil Spill. August 7.

This may refer to

1,2. Any of the Gulf of Mexico Oil spills

3. The Gulf War oil spill.

see related questions.
April 20, 2010
At approximately 9:45 p.m. on April 20, 2010
The huge oil spill in the Gulf of Mexico took place on Tuesday, April 20, 2010.
There have been two major oil spills in the Gulf Of Mexico:

April 20, 2010: BP Deepwater Horizon (Macondo Blowout) Oil spill.

June 3, 1979 : Ixtoc I oil spill.

Minor spills:

September 16, 2004: Taylor Energy wells. Hurricane Ivan caused leaks to 26 wells near Louisiana.

June 8, 1990: Mega Borg SE of Galveston. Explosions in a tanker's pump room caused fire and oil spills while transferring oil

October 23, 2007: Kab 101 - Storms caused damage to Kab 101 causing collisions, leaks resulting in evacuation of oil rigs.

The 2010 BP oil spill was initiated by a methane leak which ignited and exploded on the oil rig. The resulting, explosive event took the lives of 11 platform workers and injured 17 additional people. The valve gave out on April 20th, 2010 but the oil rig ship sank two days later (April 22nd, 2010). The oil leak continued to July 15, 86 days. The oil spill continues to exist to the present day.
It started April 20 2010