The Los Angeles Times said the Santa Monica Mountains Conservancy board voted 3-2 for the agreement.
In return, the musician and his partners will pay $750,000 (€504,900) to help pay for trail work and up to $250,000 (€168,350) for consulting services.
But the project must still get final approval and survive any legal challenges in order to receive its money and benefits. Neighbouring residents and environmentalists are concerned about biological and visual impacts in such a sensitive habitat.
The Edge, aka David Evans, has been fighting for permits to build five mansions, including his own, on Sweetwater Mesa since 2006, when he and his wife bought the 156-acre property.
But the project was hit by widespread opposition from conservation groups and the California Coastal Commission, who say it would scar an undeveloped ridgeline visible from much of the Malibu coastline and disturb features and habitats.
In 2009, the conservancy wrote a letter to the coastal commission strongly opposing the project, saying it was inconsistent with the state Coastal Act and would be impossible to build without “unavoidable significant adverse visual and ecological impacts”.
According to the agreement approved this week, the conservancy does not have to rescind the letter, but going forward, could not speak out against the project.
The conservancy is obligated to pass a resolution, write and speak in favour of the deal and may not oppose the development of three other homes proposed for nearby Carbon Mesa.
Critics characterised the deal as Evans buying the agency’s silence.
David Brown, a Sierra Club leader who sits on the conservancy’s advisory board, said: “Though you’re not really endorsing the project, you’re withdrawing your objections to it, and it’s not acceptable.”
Supporters of the deal said they did not believe the conservancy’s change in position would necessarily sway the coastal commission to support the project.