| Makotuku River | |
| Name Etymology: | Maori meaning "white heron stream" |
| Subdivision Type1: | Country |
| Subdivision Name1: | New Zealand |
| Subdivision Type2: | Region |
| Subdivision Name2: | Manawatū-Whanganui |
| Subdivision Type3: | District |
| Subdivision Name3: | Ruapehu District |
| Subdivision Type4: | Settlements |
| Subdivision Name4: | Horopito, Raetihi |
| Length: | 40km (30miles) |
| Source1: | Mount Ruapehu |
| Source1 Location: | Sunset Ridge, Tūroa skifield |
| Source1 Elevation: | 1700m (5,600feet) |
| Mouth: | Mangawhero River |
| Mouth Elevation: | 455m (1,493feet) |
| Progression: | Makotuku River → Mangawhero River → Whangaehu River |
| River System: | Whangaehu River |
The Makotuku River is a river of the west of New Zealand's North Island. It flows southwest from Tūroa ski field, on the slopes of Mount Ruapehu, and passes through the town of Raetihi before its confluence with the Mangawhero River. It has been affected by several lahars over the last 160,000 years.[1]
The New Zealand Ministry for Culture and Heritage gives a translation of "white heron stream" for Mākōtuku.[2]
The long term e. coli rating for the river at Raetihi is poor.[3]
Raetihi's drinking water comes from the river. In 2018 Veolia added activated carbon dosing, coagulation, flocculation, a lamella settler, filters and UV disinfection to the previous two settling ponds and chlorination, to minimise the effect of future pollution events.[4]
In December 1979 17000l of heating oil (diesel and kerosene) and, in September 2013, 19000l of diesel spilt into the river at the Turoa ski field,[5] 27km (17miles) upstream. The 2013 leak required Raetihi to have 21 days of water supply from road tankers.[6] The leaks had impacts on mayflies, lichens, mosses, fish and whio.[7] [8] Ruapehu Alpine Lifts Ltd was fined $300,000 for the 2013 spill.[9]
The 60 kW[10] Raetihi hydro-electric scheme produces about 1.75GWh a year and was built in 1918, about 6km (04miles) north of Raetihi. Its water comes from the Makotuku River, Makara Stream, Makaraiti Stream and a tributary of Mangaone Stream. It has a head of 116m (381feet) from its headpond to its generator, near the Orautoha Stream.[11] The original generator remains in use.[12]
The 1.2km (00.7miles) Makotuku River Walkway was upgraded in 2021, with loop tracks on the east side of Raetihi.[13] Much of the funding for the work came from the compensation paid after the 2013 oil spill.[14]