The Waihi hydro scheme is located at Lake Ruapapa on the Waihi River 26km north west of Wairoa and 78km south west of Gisborne and has a catchment area of 81.4km2 from the Panekiri range to the dam location.
Completed in 1986 the Lake Ruapapa reservoir is 5.2km in length, with an area of 42ha and holds almost 2million m2 of water.
The dam is a 15m high gated concrete buttress with earth fill flanks. A screened inlet feeds a 2.3m diameter tunnel which sends water through the twin 1.22m diameter penstocks to the powerhouse below.
The powerhouse is on the left bank of the Waiau River just upstream of the confluence with the Waihi River and about 1.9km from the dam. The powerhouse contains two 2.5MW machines with the maximum output discharge of 6m3/s and a rated net head of 100m.
Waihi generates sustainable power for 1,600 homes.