Paul Bailey's election is being touted as shifting the 5-4 majority of the Hawke's Bay Regional Council in favour of the proposed Ruataniwha Water Storage Scheme to now being against.
Widespread concern about the dam is what the new councillor believes united political views to win him a seat.
Receiving about 7700 votes from Napier residents, Mr Bailey - a two-time Green Party candidate - became one of two new councillors elected over the weekend.
Although former council chairman Fenton Wilson has said Mr Bailey's appointment might not shift the majority, the fact he was elected showed people had serious concerns about the dam.
It was not only his anti-dam stance which Mr Bailey felt drew people to vote for him, but the public knowledge of his "green bent" - having been Napier's Green Party candidate for the past two general elections.
"A lot of people saw me standing as sticking up for the environment, they thought it was safe electing a person with a green bent," he said.
"I think the message is that people who had real concerns about the dam, that covered a broad range of political views," he said, adding these were not just environmental concerns, but also economic and political.
"It proves to me how poorly [the Hawke's Bay Regional Investment Company] has managed this process."
Mr Bailey said the election results for him, and the three incumbent Hastings councillors, showed a "vote against the dam".
"The election ended up being a referendum on the dam," he said.
Mr Bailey's fellow Napier councillors - incumbent Alan Dick and former Neil Kirton - have both held the role for multiple terms.
However, Mr Bailey was not intimidated by their local government tenures, saying he had a lot of governance experience through the Green Party, and was "not afraid of the learning curve", which awaited him on council.
"I feel a huge weight of responsibility on my shoulders, but at the same time I've got my sleeves rolled up and I'm ready to get into it."