For more than a decade after World War II, Navy pilots from the El Toro Marine base dropped thousands of bombs and rockets on a large swath of south Orange County.
The target practice ended after the Korean War nearly 50 years ago. But the legacy of those bombing runs continues to haunt the area in the form of unexploded munitions hidden beneath open spaces.
The Trabuco Bombing Range now consists of the housing tracts of the city of Rancho Santa Margarita and the rolling ridges and crevices of O'Neill Regional Park. About 70 tons of bombs and rockets were excavated when the city was built, so few are believed to remain there. However, countless others remain beneath the soil in parts of the sprawling 3,100-acre county park, a popular spot for hiking, mountain biking and picnicking.
Local officials believe the munitions represent a public hazard and are unhappy at the federal government's timetable for cleanup, which would not begin for 21 years.
"Quite frankly, 2023 is really unacceptable," said Rancho Santa Margarita Councilman Gary Thompson. "We're talking about an area utilized by the public. They certainly should put a priority on that."
There is no record of any injuries caused by people coming into contact with the unexploded ordnance in Orange County, though federal authorities have recorded dozens of civilian causalities at other sites with unexploded munitions across the nation, including the death of two San Diego boys in 1983. The bombs used for practice contain only a fraction of the firepower of normal bombs, but the government said they can still cause serious injuries.
"It's like Russian roulette," said Lenny Siegel, director of the Center for Public Environmental Oversight in Washington, D.C. "You know most people won't be hurt."
The 1,812-acre bombing range is one of more than 9,000 so-called "formerly used defense sites" across the United States. About 2,500 need cleanup that will cost about $19 billion. However, federal spending has hovered around $220 million annually, said Candace Walters, a spokeswoman for the Army Corps of Engineers headquarters in Washington. "That doesn't go very far."
If that spending pace remains stagnant, cleaning up all the sites will take nearly a century.
An Oregon congressman has been pushing for years to focus more attention on the issue of unexploded munitions and former defense sites.
"No one is really in charge of dealing with the problem of unexploded ordnance, and there is not adequate funding to address it," Rep. Earl Blumenauer (D-Ore.) said.
According to a federal study that has yet to be published, at least 67 civilians have been killed and 137 injured from unexploded ordnance since World War I. Nearly half of those killed or injured were minors.
One of the most tragic and well-known accidents took place in 1983 in a northern San Diego subdivision built on a World War II artillery range. Two 8-year-old boys were killed after coming across a live mortar shell. A third boy was seriously injured.
In other cases around the nation in recent years, bomblets containing liquid sarin nerve gas were found in a national wildlife refuge near Denver, and mortar shells containing a gas that explodes when it comes in contact with air were discovered 2,100 feet from an elementary school on Cape Cod in Massachusetts.
At the Trabuco Bombing Range in south Orange County, Navy pilots from the El Toro Marine Corps Air Station used the grazing land as a bombing- and gunnery-practice range from 1944 to 1956. Aiming at a mission-era adobe hut, the men bombarded the land with 3-, 4- and 25-pound practice bombs, as well 2 1/4-, 3 1/2- and 5-inch practice rockets.
The military removed all ordnance found on the surface, and 70 tons was excavated when Rancho Santa Margarita was built. The deepest rocket was found eight feet underground. Some of the ordnance was reburied 30 feet beneath the 8th hole of the Tijeras Creek Golf Course.
Construction workers in the city find one or two practice bombs or rockets a year; the county's bomb squad is called out to dispose of it. But the park was never graded, so it's unknown how many are hidden by a few feet of eroding soil.
Bruce Buchman, the south district supervisor for the county's Public Facilities and Resources Department, said park rangers haven't found a practice bomb or rocket in two decades. But he urges park visitors not to wander off trails into unexplored wilderness.
The practice bombs contain an explosive charge designed to expel a puff of smoke to let pilots know whether they hit their target. But about 10% of the charges didn't detonate. Decades of age and exposure have made these bombs unstable and more dangerous, officials said.
"It may not kill you, but you'll lose a finger or a hand," said Debra Castens, a program manager with the Los Angeles district of the Army Corps of Engineers, which is the lead federal agency overseeing the former Trabuco Bombing Range.