SAN DIEGO (AP) -- A historic San Diego County canyon, used in the past by cattle rustlers and more recently by illegal immigrants from Mexico, is about to disappear from the landscape.

The federal government's project to fill in Smuggler's Gulch with dirt is scheduled to be completed by May. The Los Angles Times reports the government has lopped off the top of nearby hills and shoved some 1.7 million cubic yards of earth into the pass and neighboring Goat Canyon.

Border Patrol officials say the move, which includes installing lighting, fencing and surveillance cameras, will help them control the porous border.

Environmentalists fear that the project will harm endangered fauna, the Tijuana Estuary and Native American sites.