WELLTON, Ariz. (AP) -- U.S. Border Patrol agents say they found more than 400 pounds of marijuana in several backpacks at a wildlife refuge in southwestern Arizona. The drugs were spotted Wednesday while agents were patrolling the Cabeza Prieta National Wildlife Refuge. The marijuana, worth an estimated $200,000, will be destroyed. Border Patrol officials say agents in the Yuma Sector work around the clock to combat smuggling operations that try to transport contraband through the refuge. The refuge was established in 1939 to save the area's bighorn sheep. It's also a safe haven for other species, including the endangered Sonoran Pronghorn. Due to the remoteness of the Cabeza Prieta and the neighboring Organ Pipe Cactus National Monument, officials say smuggling organizations have established major routes throughout the region.