It flows generally southwest from sources south of Waingake, reaching the Wairoa River in Hawke's Bay 10 kilometres (6 mi) northeast of Frasertown.

[2] Whakapunake at 962 m (3,156 ft) is the highest point in the catchment, with the Mangarangiora Stream draining its eastern slopes into the Mangapōike.

[8][9] Lake Te Horonui formed after 25 February 2018, when about 200 m (660 ft) of a sandstone hill slipped and dammed the river.

The landslide was probably due to the river cutting into the foot of the dip slope, where water trapped in the sandstone by an impermeable mudstone may have lubricated the bedding plane.

[18] It was rejected in 1912, in favour of Hangaroa, Waikura and Ngātapa, as they served an area thought to have more economic potential.

In October 1942 ratepayers approved a £45,000 loan for a 246 million gallon 246,000,000 imp gal (1,120,000 m3) reservoir, designed by G. F. Clapcott, the borough engineer, with a 3.25 mi (5.23 km) pipeline and an 80 ft (24 m) tunnel to Te Ārai valley.

[32] In 2023 Cyclone Gabrielle damaged 9 of the 21water pipe bridges in the network and left two of reservoirs with cloudy water.

[34] The Cyclone also left forestry slash backed up for more than 50 m (160 ft) at the bridge where the Mangapōike joins the Wairoa.