SAN DIEGO -- Drug enforcement officials discovered a 29,000-plant crop of marijuana -- with an estimated street value of $116 million -- on the Santa Ysabel Indian Reservation near Highway 79 and Highway 76, the agency told 10News Tuesday.

Officers with the U.S. Drug Enforcement Administration and the Narcotics Task Force, which is made up of law enforcement from around the region, spent 9 hours in triple-digit temperatures to investigate the area where the plants were being grown.

Authorities at the scene gathered evidence, including equipment possibly used to grow and manufacture the drugs.

The plants had to be airlifted out of the area because the terrain was considered too treacherous to transport out over the ground.

Deputy Steve Reed of the county task force told 10News the discovery of water lines led authorities to the marijuana farm.

"We got some reports of water lines that shouldn't have been where they were, [we] didn't know where they went. We flew over, figured it was probably marijuana, and sure enough, it was," said Reed.

10News' Joe Little reported no arrests were made and authorities did not know who was connected to the marijuana plants.

Officials with the Santa Ysabel Indian Reservation were assisting authorities with the investigation, and Little reported tribe members were not being linked to the crops.

Reed said Tuesday's discovery was the second-largest this year. He told 10News agents found 41,000 plants near Palomar Mountain earlier this year.

Authorities told 10News the plants will be destroyed later this week.