Turlock Irrigation District received reports Wednesday that two males claiming to be with the utility were knocking on doors, saying they needed access to the homes to check electrical plugs.
"Do not let them in," TID tweeted. "... They are definitely not TID employees."
TID received just a few calls, spokesman Calvin Curtin said, "but for every person who calls, who knows how many don't?" The reported incidents were in the areas of Keyes and Bystrom, he said.
The two males were wearing blue T-shirts that had "TID" printed on them, Curtin said.
The Stanislaus County Sheriff's Department retweeted the TID tweet, which encouraged customers to get a description of the males and call law enforcement.
The Sheriff's Department nonemergency dispatch number is 209-552-2468. For Turlock police, call 209-668-5550. Anyone who feels threatened should call 911.