Around five thousand people visited the Clyde Dam and hydro-electric power station on Saturday, the first open day since the station opened.

The open day celebrates 25 years since the filling of Lake Dunstan began, on April 22, 1992.

Visitors took self-guided tours around the 60-metre-high dam and powerhouse, including seeing the machines that generate the station's 464MW output, with release of water down the spillways thrilling many of those who visited the facility.