Because of the area's history as a military training base, some military debris including unexploded ordnance remained in the area when it was developed, in spite of multiple cleanup efforts by different branches of the services. In 1983 two 8-year-old Tierrasanta boys were killed after discovering unexploded ordnance in a canyon near their home. The military has performed clearance operations as recently as 1994 and the U.S. Army Corps of Engineers continues to investigate the area every five years under its FUDS Formerly Used Defense Sites program.