In this quiet, pastoral corner of Southern California, the U.S. Navy is preparing to get rid of one of America's ugliest legacies of the Vietnam War - napalm.

About 23 million pounds of the sticky, flammable substance have been sitting in 35,100 jungle-green canisters at the Fallbrook Naval Weapons Station here for 20 years.Some of the bombs have been leaking, at least 156 of them so badly that they had to be removed and incinerated, Navy officials said.

The toxic stockpile has some local residents frightened, but others are unfazed, accepting such hazards as the price they pay for the heavy concentration of military installations in San Diego County.

The big question now is what to do with it.

The use of napalm - a mixture of gasoline, benzene and polystyrene plastic - mostly ended with the withdrawal of U.S. troops from Vietnam about 20 years ago. There, during the height of the conflict, the use of napalm by U.S. forces came to symbolize the worst side of America's involvement in the fighting.

Napalm bombs were dropped as a defoliant to clear large stretches of dense jungle and as a weapon to burn out Viet Cong guerrilla forces - sometimes at a cost of civilian casualties.

Worldwide the image of random destruction wrought by napalm hit home in movies like "Apocalypse Now" and in the legendary photo of a naked young Vietnamese girl, her skin seared, running terror-stricken from the scene of an attack.

For almost a generation, the last of the military's stock has sat in wooden crates on three dirt sites here until the first leak was discovered in 1989.

This year, 1,780 canisters have been found leaking, according to Eike Hohenadl, the Navy's napalm project manager. All but a few of them have been repaired by re-welding or replacing gaskets, where the thick, jellylike material had oozed out and hardened.

While state environmental officials don't consider the canisters hazardous, especially since they no longer contain detonators, they still want them removed.

Failure to do so under the Federal Facilities Compliance Act could cost the Navy as much as $25,000 per canister for each day the waste remains.

Environmental officials are worried about the potential for ground water contamination or the release of benzene vapors, although the air at the sites has tested cleaner than on the grounds of a local high school, said Rich Varenchik of the California Department of Toxic Substance Control.