5. Waikato Region
5.1 Catchment #2: Waikato
This catchment has:
- The largest catchment area of the North Island, including:
- Lake Taupo and its catchment
- Waikato River below Lake Taupo outlet
- Waipa River
- numerous existing hydro-electric power stations (grid or network connected) (also used for cooling Huntly Power Station),
- controlled lake storage (e.g. Lake Taupo, and Lake Moawhango (on the Rangitikei)).
Table 5: Hydropower Opportunities in the Waikato Catchment with High to Medium Confidence of Proceeding in the Next 20 Years.| Name | MW | Average Energy Production (GWh p.a.) | Public Reference |
| Wairehu Canal | 9 | 40 | SKM 2004 |
| Waipapa River | 5 | 21 | T&T 1982-1 |
| Waipa River C/2A | 10 | 44 | T&T 1982-1 |
| Waipa River C/2B | 2 | 11 | T&T 1982-1 |
5.1.1 Wairehu Canal
This canal is used to transfer water from the Whanganui catchment to the Taupo / Waikato catchment as part of the Tongariro Power Scheme and has a 37m head differential. The surplus head is dissipated at drop structures along the Wairehu canal between Lakes Otamangakau and Rotoaira and has always been recognised as potential for hydro development.
The proposed scheme configuration is likely to be:
- An intake located between the existing drum screens and the Wairehu canal control gate at the outlet to Lake Otamangakau
- A canal or pipeline running alongside the existing canal to a headpond downstream from the State Highway 47 road crossing
- Penstocks, power station etc towards the Lake Rotoaira end of the canal,
A recent estimate is for a 9MW power station yielding approximately 40GWh p.a. (50% plant factor).
Possible Interest - Genesis (Owner of Wairehu Canal)
5.1.2 Waipapa River (B/5A)
The Waipapa River and its tributaries rise in the steep afforested Rangitoto Range west of Whakamaru and flow in a predominantly north easterly direction to reach the Waikato River a short distance from the Waipapa hydro dam. In its middle reaches west of Mangakino, both the river and its adjacent main tributary exhibit favourable combinations of flow and channel gradients for run-of-river diversion type hydro schemes.
A possible development option is a 2km long canal on the left bank7, crossing a tableland west of the road, where a headpond could be provided, to discharge into an unnamed stream; a small power station may be economic at the drop into the stream . The combined flows of the diversion and the unnamed stream would then be picked up at the 350m level and carried by a canal, pipeline and penstock to a power station close to the confluence with the Waipapa River.
The mean flow from the 26km² catchment is estimated to be 1m³/s. With an installed capacity of 4.8MW, 21GWh p.a. would be available (50% plant factor).
5.1.3 Waipa River (C/2A & C/2B)
The Waipa River, and one of its upper tributaries the Tunawaea Stream, rise in the steep afforested Rangitoto Range between Te Kuiti and Mangakino. Near their confluence in the Waipa Valley both rivers fall steeply over rapids along narrow gorges and afford potential for substantially run-of-river diversion type hydro schemes.
The C/2A scheme headworks would be located 100m downstream of Okahura Stream confluence and 1km upstream from the Owiwi Rapids with a tunnel and pipe, into a power station located 0.5km above Tunawaea Stream confluence. The catchment area of 147km², and a mean flow rate of 7m³/s and head of 102m, with a 10MW generator would give approximately 44GWh p.a. (50% plant factor).
The C/2B scheme headworks would be located at 380m contour on the Waipa River, with a natural channel down to a power station at the Okahura confluence. The 93km² catchment area, with a mean flow rate of 3.5m³/s, head of 39m, and a 2MW generator would give approximately 11GWh p.a. (50% plant factor).
5.2 Other Opportunities in this Region
5.2.1 Prohibited
#224 Marakopa River Falls - 6.7MW (Scenic Reserve)
5.2.2 Undefined
#2 Waikato catchment
Lake Taupo Gates
Tauranga Taupo River Headwaters - 5MW
Waihaha River West Taupo - 10MW ([MOC 1990], Blue Duck, river of national importance)
Waikato River at Huka Falls - 5MW
Tongariro Power Scheme enhancements
Waihohonu stream and nearby rivers and streams upstream of the Tongariro Power Scheme
There are several locations adjacent to the Waikato River which could be developed for out-of-river storage. These could be in the form of pumped schemes or utilised for flood storage.
#59 Mokau catchment
Although having two existing power stations totalling 6.5MW, further opportunities in the catchment have generally not been investigated because of perceived economic, distance from transmission and other infrastructure, and possible environmental issues.
Mokau - 50MW
Back to Top