8. Hawkes Bay Region
8.1 Catchment #16: Wairoa (Hawkes Bay)
This catchment, the fifth in size in the North Island, has:
- existing hydro-electric power stations (e.g. Tuai, Kaitawa, Piripaua, Waihi)
- lake storage (Lake Waikaremoana).
Table 11: Hydropower Opportunities in the Wairoa (Hawkes Bay) Catchment with High to Medium Confidence of Proceeding in the Next 20 Years. | Name | MW | Average Energy Production (GWh p.a.) | Public Reference |
| Wairoa - Mangapoike | 11 | 47 | BA 1981 |
8.1.1 Wairoa - Mangapoike
The Mangapoike Valley rises in elevated country to the north-west of Mahia Peninsula, and the River itself flows largely parallel to the Hawke's Bay shoreline, in a westerly direction to join the Wairoa River at its downstream limit.
A small part of the headwaters of this river is diverted for the Gisborne Water Supply and it is notable, considering the matter of road access to the river, that the upper reaches of the river are reached by road from the Gisborne direction while road access to the lower reaches of the river from Frasertown near Wairoa. No through road exists.
Two options have been proposed, one with a high dam which would result in a 23MW generating capacity, or a lower output one, approximately 11MW, which would significantly reduce the area of land inundated. The lower output option would deliver approximately 47GWh p.a. (plant factor 50%).
8.2 Catchment #34: Mohaka
This catchment has:
- no existing hydro-electric power stations,
- no controlled lake storage.
Table 12: Hydropower Opportunities in the Mohaka Catchment with High to Medium Confidence of Proceeding in the Next 20 Years.| Name | MW | Average Energy Production (GWh p.a.) | Public Reference |
| Mohaka (Raupunga) | 75 | 330 | ECNZ 1992, W20/92 |
8.2.1 Mohaka (Raupunga) (M15)
From its source in the Kaweka Ranges, the Mohaka River travels 172km into the mouth at Mohaka in Hawkes' Bay. The catchment is steep and rugged, and at 2430km², is eleventh in size in the North Island. A suitable site for a dam is in the lower reaches of the river near Raupunga about 15km upstream from the mouth.
In evidence given by B. E. Cox for Electricorp regarding the application for a Water Conservation Order for the Mohaka River system in 1991, two dam configurations were considered as possible development schemes at the Raupunga site. A lower one with an 80m head and a higher one at 100m with installed capacities of 85MW and 105MW respectively.
The 1992 Planning Tribunal report and recommendations on the Mohaka River Water Conservation Order regarding electricity generation identifies that a 70m dam at Raupunga can be accommodated without endangering the outstanding qualities of the river. This idea appears to be reflected in the amended draft water conservation order where development may be allowed below Willowflat.
The level of the lake formed and the height of the dam formed would need to meet the requirements of a Mohaka River Water Conservation Order (currently in draft form).
A 70m dam with an installed capacity of 75MW with a 50% plant factor would result in an annual average of 330GWh per year of electricity being generated.
8.3 Catchment #21: Ngaruroro
This catchment is the seventh in size in the North Island and has:
- no existing hydro-electric power stations,
- no controlled lake storage.
Table 13: Hydropower Opportunities in the Ngaruroro Catchment with High to Medium Confidence of Proceeding in the Next 20 Years.| Name | MW | Average Energy Production (GWh p.a.) | Public Reference |
| Ngaruroro (Below Taruarau) 6/3 | 21 | 92 | T&T 1981-3 |
| Ngaruroro (Above Taruarau) 6/7 | 24 | 103 | T&T 1981-3 |
| Ngaruroro (Whanawhana Scheme) 6/21A | 30 | 131 | T&T 1981-3 |
| Ngaruroro (Above Whanawhana) 6/1 | 22 | 95 | T&T 1981-3 |
| Upper Ngaruroro - 6/10 | 37 | 164 | T&T 1981-3 |
8.3.1 Ngaruroro (Below Taruarau) (6/3)
This scheme would consist of a 50m high earth / rock dam with an adjacent powerhouse.
A catchment area of 978km² gives a mean annual flow rate of 33.2m³/s, and with a 100ha intake reservoir, a nett head of 43m and a 21MW generator would give approximately 92GWh p.a. (50% plant factor).
8.3.2 Ngaruroro (Above Taruarau) (6/7)
This scheme would consist of a 41m high concrete dam and a 0.5km long tunnel to a powerhouse.
A catchment area of 463km² gives a mean annual flow rate of 19.8m³/s, and with a 21ha intake reservoir, a nett head of 85m and a 24MW generator would give approximately 103GWh p.a. (50% plant factor).
8.3.3 Ngaruroro (Whanawhana Scheme) (6/21A)
The downstream end of the Ngaruroro River gorge at Whanawhana offers a reasonable damsite, provided problems of spillway capacity and shingle movement can be accommodated.
A catchment area of 1100km² gives a mean annual flow rate of 36.5m³/s, and with a 380ha intake reservoir, nett head of 55m and a 30MW generator would give approximately 131GWh p.a. (50% plant factor).
8.3.4 Ngaruroro (Above Whanawhana) (6/1)
This scheme would consist of a 52m high concrete dam and an adjacent powerhouse.
A catchment area of 1104km² gives a mean annual flow rate of 36.4m³/s, and with a 260ha intake reservoir, a nett head of 39m and a 21.6MW generator would give approximately 95GWh p.a. (50% plant factor).
8.3.5 Upper Ngaruroro (6/10)
A catchment area of 365km² gives a mean annual flow rate of 16.9m³/s, and with a 50ha intake reservoir, a nett head of 153m and a 37.4MW generator would give approximately 164GWh p.a. (50% plant factor).
8.4 Catchment #33: Tukituki
This catchment, the tenth largest in size in the North Island, has:
- no existing hydro-electric power stations,
- no controlled lake storage.
Table 14: Hydropower Opportunities in the Tukituki Catchment with High to Medium Confidence of Proceeding in the Next 20 Years.| Name | MW | Average Energy Production (GWh p.a.) | Public Reference |
| Tukituki | 9 | 39 | TBA |
8.4.1 Tukituki
The Tukituki River flows from its headwaters in the Ruahine Range to its mouth at Haumoana in Hawkes Bay. An opportunity being investigated jointly by Centralines Ltd and Meridian Energy Ltd for a combined hydro/irrigation scheme would use a 12km canal running from just downstream of Waipawa past Otane and rejoining the river about 5km downstream of Patangata. An installed capacity of 9MW could be realised, which would give approximately 39GWh p.a. assuming plant factor of 50%.
Potential Interest - Centralines / Meridian Energy (Current Investigations)
8.5 Other Opportunities in this Region
8.5.1 Prohibited
There are no known prohibited opportunities.
8.5.2 Undefined
#33 Tukituki - Makaroro above Wakarara - 4MW
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