Organisers are expecting about 360 people for the Otematata Village People Reunion, which starts today and ends on Sunday.
The township has about 186 permanent residents (according to the 2013 census).
The event marks 50 years since the dam started producing electricity in 1965 and was officially commissioned by then prime minister Sir Keith Holyoake.
While there had been Otematata School reunions in the past, this was the first for the village.
Event organiser Vicky Munro said some of those attending included family members of original residents who were visiting for the first time to see where their parents or grandparents lived while working on the dam.
Visitors were coming from as far away as Ireland. Others included those born in Otematata who lived and worked there including when construction switched to the Aviemore Dam, and people who had businesses in the township.
Work started on creating Otematata in 1957 as the construction camp for the Benmore Dam, and the first 150 workers arrived in January 1958.
At the time, the dam was the biggest man-made structure in New Zealand and the largest earth dam in the southern hemisphere.
At its peak, Otematata had 4166 people, a shopping centre, a large number of sports clubs, primary and high schools and a hospital whose maternity wing had 179 births in 1964.
The reunion weekend starts with a get-together at the Otematata District Club, which was the gymnasium back when the village was booming, from 4pm today.
Tomorrow, Meridian Energy (which owns the Waitaki Valley hydro stations except Tekapo) will run guided bus tours from Otematata to the dam for people who have registered for the reunion.
A dinner with two sittings will start at 5pm in the Otematata Community Centre, followed by an official function and welcome at the Otematata Lakes Hotel.
On Sunday, a fundraising brunch is being offered for the Otematata Fire Brigade.
