A tip from managers at the Las Virgenes Municipal Water District led to an investigation of drug dealing at the Calabasas plant and the arrests of three men, including two district employees, the Los Angeles County Sheriff's Department said this morning.

The suspects were arrested at the district water plant in the 14200 block of Las Virgenes Road after a six-week investigation during which undercover deputies bought drugs six times from the suspects, Sgt. John Andrews said.

Som Guar, 21, of Granada Hills and Richard Zuniga, 30, of Thousand Oaks, both district employees, were arrested on suspicion of possession of a controlled substance and selling marijuana. The third suspect, Samuel Villano, 26, of Chatsworth, who is not employed by the district, was arrested on suspicion of possession of a controlled substance and selling cocaine.

Six ounces of cocaine and a small amount of marijuana were confiscated from the men, Andrews said.