An explosive ordnance disposal diving team based at Naval Air Station Fallon in Fallon, Nev. removed the unloaded AT4 from the aqueduct about two miles south of Patterson near Oak Flat Road at about 9:45 p.m. after entering the water about 30 minutes earlier.
"Everything went perfect," said Joel Ledesma, Delta field division chief of the state Department of Water Resources, giving kudos to Navy dive team members for their work.
Plant growth on the rocket launcher indicated the weapon had been in the water for more than a year, said EODCS Bob Frew, lead petty officer of the explosive ordnance detachment that removed the rocket launcher. At the same time, the weapon appeared to be in relatively good shape, so it probably had not been in the water for five years or more, he said.
"It is definitely U.S. military inventory," Frew said. "I don't know how it ended up there."
The Navy will seek to trace down the rocket launcher's lot number and find out how it ended up in the aqueduct and then destroy it, Frew said.
Caltrans dive team members found the weapon at about 3 p.m. Wednesday, Jan. 30 while doing a routine inspection of the Oak Flat Road bridge over the aqueduct, according to Caltrans and Department of Water Resources representatives.
The detachment that retrieved the rocket launcher Thursday serves a response area that includes parts of California, Nevada, Utah and southern Oregon, Frew said. Frequently, the group assists communities that do not have bomb squads of their own, he said.
While there was no rocket inside the launcher that the dive team retrieved, Frew noted the group has found live ammunition from old bombing ranges that end up in bodies of water at times.
His detachment also has retrieved torpedoes, depth charges and grenades used by both the U.S. military and foreign armies, he said.
"We've had worse things in waterways," he said Thursday, a few minutes after his detachment removed the AT4 from the aqueduct.