He believed "tonnes" of soil had dropped on to the beach below.
The power poles are on Te Ariki Park, at the end of Maungatapu Rd, home of the Rangataua Sports and Cultural Club. Te Ariki Park is next to, and owned by, Maungatapu Marae.
"If it keeps raining like it was over the weekend then it could cause a lot of problems because it's not going to stop eroding," said Hinerongo Walker, a marae trustee who has lived in Maungatapu all her life. "I went down there to have a look and it's bad. Straight away I saw [the slip]. It's really dangerous."
Mrs Walker said the community had been rallying against Transpower for the past five to six years.
Transpower spokesperson Rebecca Wilson said a patroller visited the site after the weekend rain and the power poles were "completely stable".