El Toro MCAS was closed on July 2, 1999 as part of the Federal Base Realignment and Closure (BRAC) process. On March 6, 2002, the federal government announced that the property would be sold to private owners through an on-line public auction managed by the General Service Administration and would be subject to local zoning regulations.

The Department of the Navy sold the property on February 16, 2005 to the winning bidder, Lennar Corporation, for $649 million. As a condition of the sale of the property, Lennar Corporation signed a Development Agreement that deeded 1,347 acres to the City of Irvine for the Orange County Great Park and agreed to pay an additional $200 million for future development and maintenance of the Park.

The Orange County Great Park Plan will provide a wide array of active and passive uses, including a 2.5 mile canyon and lake, miles of walking and biking trails, a cultural terrace, Orange County's largest sports park, a botanical garden, and a tethered helium observation balloon that will be an icon for the Great Park. More than 3,885 of the 4,700 acres will be dedicated to open space, education, and other public uses.

The Orange County Great Park will include over 1,300 acres of magnificent public spaces, including:

• 2.5 mile canyon
• More than 20-acre lake
• Cultural Terrace
• Botanical Gardens
• Great Lawn
• Performing Arts Venue
• Veterans Memorial
• Aircraft Museum
• Sports Park
• 974-acre nature preserve
• Wildlife corridor linking the Cleveland National Forest to the Laguna Coast Wilderness Park