14. Canterbury Region
14.1 Catchment #23: Waiau
This catchment has:
- no existing hydro-electric power stations,
- no controlled lake storage.
Table 25: Hydropower Opportunities in the Waiau (Canterbury) Catchment with High to Medium Confidence of Proceeding in the Next 20 Years.| Name | MW | Average Energy Production (GWh p.a.) | Public Reference |
| Clarence to Waiau Diversion | 70 | 300 | NHRA 8 |
| Upper Waiau | 56 | 240 | NHRA 8 |
| Mid Waiau | 60 | 270 | NHRA 8 |
| Lower Waiau | 50 | 220 | NHRA 8 |
14.1.1 Clarence to Waiau Diversion
The arrangement investigated for this opportunity diverts water from the Clarence catchment into the Waiau catchment near Hanmer Springs. A concrete dam/spillway would be located on the Clarence approximately 1500m downstream of the Jollies Pass road where the river is flowing predominately northwards. The dam would raise the water level 30m and divert it through a 3500m tunnel to a surge chamber and powerhouse near Hanmer Springs. A six kilometre tailrace canal would then discharge water into the Hanmer River about six kilometres from its confluence with the Waiau. An installed capacity of 70MW would give approximately 300GWh p.a. (50% plant factor)
14.1.2 Upper Waiau (W97)
This scheme is based on damming the Waiau midway between the Hope confluence and Hanmer Plain, where the river is flowing predominantly eastward. The dam/spillway would raise the water level 46m and generate power in an adjacent powerhouse. An installed capacity of 56MW would give an annual output of approximately 240GWh p.a. (50% plant factor).
14.1.3 Mid Waiau (W81)
This scheme has been assumed to be integrated with the Clarence C171 scheme.
The scheme would be located in a gorge in the Waiau downstream from Hanmer Springs, at a locality known as "Hells Gate Corner", some 81km from the mouth. The river at this point abruptly changes course from flowing predominantly eastward to flowing predominantly southward on leaving Hanmer Plain. The scheme consists of a dam/spillway raising the water level some 40m, with an associated powerhouse. An installed capacity of 60MW would give an annual output of approximately 270GWh p.a. (50% plant factor).
14.1.4 Lower Waiau (W2)
The scheme studied would involve damming the Waiau two kilometres from the mouth of the river where the river is flowing predominantly south-eastward. The dam/spillway would raise the water level 25m and pass it to a powerhouse sited on more gentle slopes about 300m below the dam. An installed capacity of 50MW would give approximately 220GWh p.a. (50% plant factor).
14.2 Catchment #31: Hurunui
This catchment has:
- no existing hydro-electric power stations,
- no controlled lake storage.
Table 26: Hydropower Opportunities in the Hurunui Catchment with High to Medium Confidence of Proceeding in the Next 20 Years.| Name | MW | Average Energy Production (GWh p.a.) | Public Reference |
| Hurunui (H24) | 36 | 160 | NHRA 8 |
| Hurunui (H36) | 43 | 190 | NHRA 8 |
14.2.1 Hurunui (H24)
Two possible dam sites on the lower Hurunui where the river is entrenched in the Lowry Peaks Range were suggested.
The proposed dam site would be upstream of the State Highway 1 bridge. The mean annual flow at this point is estimated (from earlier work) to be 58m³/s. The river is still entrenched in the Lowry Peaks Range at this point.
The available flow and 45m head at this site, with a 36MW generator, would give approximately 160GWh p.a. (50% plant factor).
14.2.2 Hurunui (H36)
This envisages a dam sited just below the Pahau River confluence and would raise the water by about 48m. The power station, with an installed capacity of 43MW, would give approximately 190GWh p.a. (50% plant factor).
14.3 Catchment #51: Ashburton
This catchment has:
- no existing hydro-electric power stations,
- no controlled lake storage.
Table 27: Hydropower Opportunities in the Ashburton Catchment with High to Medium Confidence of Proceeding in the Next 20 Years.| Name | MW | Average Energy Production (GWhp.a.) | Public Reference |
| Blowing Point | 7 | 31 | CPWN #2 |
14.3.1 Blowing Point
An irrigation water enhancement scheme pre-feasibility study for the Ashburton Community Water Trust identifies opportunities that would draw water at times of higher flows from high country tributaries in the Rangitata, Ashburton and Rakaia catchments. This water would be channelled into one or more storage reservoirs, with potential sites identified in the Stour River valley and at Blowing Point in the Ashburton gorge. There is a possibility of a 7 to 8MW power station being incorporated into a Blowing Point Dam, giving approximately 31GWh p.a. (50% plant factor).
14.4 Catchment #3: Waitaki
This catchment has:
- the largest storage capacity of New Zealand lakes for hydro-electric use
- existing hydro-electric power stations (e.g. Benmore, Waitaki),
- controlled lake storage (Tekapo, Pukaki, Ohau)
Table 28: Hydropower Opportunities in the Waitaki Catchment with High to Medium Confidence of Proceeding in the Next 20 Years.| Name | MW | Average Energy Production (GWh p.a.) | Public Reference |
| Project Aqua | 524 | 3000 | MEL 2004 |
| Pukaki Canal Intake | 44 | 120 | SKM 2003 |
| Hopkins River | 9 | 37 | RSML 1982-2 |
| Waiareka-Kakanui Irrigation Scheme | 11 | 51 | RSML 1982-2 |
14.4.1 Project Aqua
Project Aqua is a proposed hydro-electric scheme that would run along a 60km canal on the south side of the lower Waitaki River. It would comprise six individual generation units in series, with a combined total capacity of around 524MW. It is expected to generate around 3,000GWh in a mean hydro year, and around 2,000GWh in a 1-in-20 dry-year. (Note: Generation statistics from MEL)
14.4.2 Pukaki Canal Intake
The difference in head between Lake Pukaki and the Pukaki - Ohau A Canal that conveys the lake water to Ohau A power station can be utilised for generation.
A recent review study identified, among a number of opportunities, building a new low station at Pukaki dam canal intake. This station would have an output of about 40MW when the lake was full. As the head for this station will change significantly with normal operational changes in the level of Lake Pukaki, the amount of energy generated (indicatively 120GWh p.a.9) will be very dependant on the management of Lake Pukaki storage.
14.4.3 Hopkins River
Desk studies have indicated a possible small hydro scheme on the Hopkins River. The scheme would divert the river at the 580m contour, the narrowest point, with a 5,500m headrace on the right bank, to a headpond. From here water would be conveyed by twin penstocks to a powerhouse at river bed level. The race would cross five small side streams.
This scheme would have an estimated mean annual flow at intake 24.5m³/s. A 30m head and an installed capacity of 9MW would give approximately 37GWh p.a. (50% plant factor).
As a concrete stream bed intake structure would not be practical in this river because of size and cost, a system similar to the Wilberforce River diversion into Lake Coleridge could be feasible.
14.4.4 Waiareka-Kakanui Irrigation Scheme
The Ministry of Works and Development had proposals to irrigate the Waiareka-Kakanui district. With an irrigation scheme that would abstract 22m³/s from the Waitaki River near the 150m contour with a 24km race to a tunnel portal near the Awamoko Stream. A 3km tunnel would then convey water to the Waiareka-Kakanui valley for distribution in the irrigation race network, with some 60m head available from the irrigation race at the Awamoko Stream to the Waitaki River.
The irrigation flow would be shut off at the tunnel portal and a power station or stations totalling 11MW built to use this head. A headpond would be incorporated in the main race. The tailrace would then connect into the Awamoko Stream.
The forecast energy output (of 51GWh p.a.) has been based on an 85 % plant factor for 7 months of the year.
This ability to take up opportunity will be dependent on the outcome of decisions on Project Aqua and irrigation proposals in this area.
14.5 Other Opportunities in this Region
There are a number of rivers in Canterbury where other opportunities have been identified. This is the region most likely to have further hydro-electric development associated with irrigation (Highbank and Montalto are existing power stations associated with the Rangitata Diversion Race).
14.5.1 Prohibited
Restrictions in the Canterbury Region include National Water Conservation (Ahuriri River) Order 1990 and National Water Conservation (Rakaia River) Order 1988.
#3 Ahuriri - Avon Burn (1 & 2) - 6MW
#30 Rakaia - 35MW
14.5.2 Undefined
#17 Waimakariri - 100MW
#24 Lower Clarence
#23 Waiau - Kakapo Brook - 5MW
#77 Ashley catchment
Ashley River - 5MW
Ashley Gorge dam - 8MW
#472 Rangitata - 50MW
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