12. Nelson-Marlborough Region
12.1 Catchment #106: Pelorus
This catchment has:
- no existing hydro-electric power stations (excluding network connected stations),
- no controlled lake storage.
Table 20: Hydropower Opportunities in the Pelorus Catchment with High to Medium Confidence of Proceeding in the Next 20 Years.| Name | MW | Average Energy Production (GWh p.a.) | Public Reference |
| Pelorus | 7 | 32 | RSML 1981-2 |
12.1.1 Pelorus River
A site was found where the topography seemed favourable for the construction of a rock fill dam. The proposed dam site, at Rainy River, is 6.5km downstream of Pelorus Bridge on State Highway 6. It was proposed that the dam would be constructed some 120m upstream of the Pelorus and Rainy river confluence. At this point, the gorge is approximately 40m deep and the river bed some 15m wide. Therefore it is assumed that an average annual flow of 17m³/s at the dam site could be expected. The 40m head and an installed capacity of 7MW would deliver approximately 32GWh p.a. (50% plant factor).
12.2 Catchment #18: Wairau
This catchment has:
- existing hydro-electric power stations, (e.g. Branch, Waihopai)
- no significant controlled lake storage.
Table 21: Hydropower Opportunities in the Wairau Catchment with High to Medium Confidence of Proceeding in the Next 20 Years.| Name | MW | Average Energy Production (GWh p.a.) | Public Reference |
| Wairau | 100 | 500 | TPL 2003-1 |
| Waihopai | 6 | 26 | RSML 1981-2 |
12.2.1 Wairau
The proposed scheme is an extension of TrustPower's Branch hydroelectric scheme. Under the project, part of the Wairau River flow would be diverted into the existing Branch scheme and the water conveyed through interconnecting canals and penstocks to new power stations, with the tailrace of the last station at the end of the Wairau Valley, about 25km south west of Blenheim.
With a proposed additional installed capacity of approximately 100MW, the scheme would generate about an additional 500GWh of electrical energy annually.
TrustPower are currently carrying out an environmental feasibility assessment and have indicated that, subject to project feasibility, they expect to apply for resource consents in April this year.
Possible Interest - TrustPower (owns existing power stations, investigating the opportunity).
12.2.2 Waihopai
The Waihopai River has its source in the mountains east of the Leatham and Branch Rivers. It flows north-east to join the Wairau upstream of Renwick. Desk studies indicated a possible scheme on the lower Waihopai River with an intake upstream of the bridge adjacent to the 150m contour for 9km along the base of the left bank foothills. As the river is entrenched in rock for 3-4m, a large concrete weir structure would be required to abstract water at the terrace level.
This scheme would also have an irrigation potential of some 1600ha of prime farmland.
From an installed flow of 25m³/s, and with a head of 30m, an installed capacity 6MW would give approximately 26GWh at 50% plant factor.
12.3 Catchment #54: Awatere
This catchment has:
- no existing hydro-electric power stations,
- no controlled lake storage.
Table 22: Hydropower Opportunities in the Awatere Catchment with High to Medium Confidence of Proceeding in the Next 20 Years.| Name | MW | Average Energy Production (GWh p.a.) | Public Reference |
| Middle Awatere | 12 | 50 | RSML 1981-2 |
12.3.1 Middle Awatere
The section of river from Gladstone Bridge to the Medway River confluence is referred to in this report as the Middle Awatere. There are several dam sites in the gorge and the best one was considered to be some 4km upstream of the Jordan River confluence (about 35km up the Awatere Valley from Seddon).
The mean annual flow recorded is 20.94m³/s. A 49m high earth dam could be constructed in the gorge with nett head of 46m which, with an installed capacity of 12MW, would deliver approximately 50GWhp.a. (50% plant factor).
12.4 Catchment #126: Waimea
This catchment has:
- no existing hydro-electric power stations,
- no controlled lake storage.
Table 23: Hydropower Opportunities in the Waimea Catchment with High to Medium Confidence of Proceeding in the Next 20 Years.| Name | MW | Average Energy Production (GWh p.a.) | Public Reference |
| Wairoa Gorge | 16 | 70 | NZERDC 1979 |
12.4.1 Wairoa Gorge
At the point at which the Wairoa River emerges from steep hilly country on the Waimea Plains near Wakefield (south-west of Nelson), it has a gauged mean flow of over 16m³/s. About 2km upstream from this point the river forks with approximately half the total flow coming from each of the Wairoa to the west and the combined Lee and Roding catchments to the east.
The proposal involves the damming of the Wairoa immediately downstream of the Lee River confluence to create a head of 90m with the purpose of creating benefits from flood mitigation, irrigation, town water supply, recreation, and electricity generation. If it can be shown that the economic benefits of such a scheme justify its construction then it could provide useful power for the area, with a proposed peak output of 16MW, delivering approximately 70GWh p.a. (50% plant factor).
12.5 Other Opportunities in this Region
12.5.1 Prohibited
#18 Waihopai River - 6MW
12.5.2 Undefined
#41 Motueka - 39MW
#54 Upper Awatere River - 4MW
#109 Takaka
Cobb Scheme Supplement - 5MW
Anatoki River - 13MW
#222 Aorere - Finney Creek - 30MW
Back to Top