3 Waitaki Hydro Scheme
3.1 Introduction
This section sets out matters relating to the operation of Waitaki Hydro Scheme. It describes the existing consents, the current environmental issues of the Waitaki Hydro Scheme, and the potential effects following the separation of SISOE.
3.2 Status of Consents, Conditions and Agreements
The Waitaki Hydro Scheme is a system of natural and artificial lakes, canals and dams in the Mackenzie Basin. In 1991, the Canterbury Regional Council granted sixty-three water rights with twenty-two conditions, under the Water and Soil Conservation Act 1967 ("WSCA"). The water rights, which are now deemed resource consents pursuant to the transitional provisions of the Resource Management Act 1991 ("RMA") expire on 30 April 2025. The consents were granted virtually via consensus, as a result of the extensive consultation undertaken between ECNZ and the Waitaki Working Party (a group comprising all key stakeholders).
Nine "Agreements to Electricity Corporation's Water Rights" documents have been signed by ECNZ as a result of consultation with interested parties prior to the granting of the water rights. Most of these agreements include a clause requiring a seven-yearly review of the matters covered by the agreement.
In the "Agreement to Electricity Corporation's Water Rights" between ECNZ and twelve interested parties constituting the Waitaki Working Party, dated 26 November 1990, a clause stated "that the parties agree that the Canterbury Regional Council be requested to issue the rights for a term of 35 years ... with a review every seven years, to examine their appropriateness and efficiency". The water rights do not include this review clause as a consent condition, and in fact could not have been, as a review mechanism was not provided for in the WSCA.
However a review is currently being carried out and a scoping report has been prepared providing a preliminary list of issues that may need to be covered in the review process. In addition, a consultation process with interested parties and stakeholders has commenced.
The consultation with the parties to the agreement provides an opportunity for SISOE to develop ongoing working relationships with stakeholders.
Matters relating to the review include the following:
- The initial parties agreed that only the conditions agreed to as part of the "General Agreement" would be subject to review. All the key operational rules for the Waitaki Hydro Scheme conditions are in this category.
- The consent itself and its term are not matters for negotiation.
- Only those parties comprising the initial Waitaki Working Party could participate in the review.
- A condition would be subject to a review process only if a majority of the Working Party agreed.
Matters that are likely to arise relate to the provision of minimum flows required in the Pukaki, Tekapo and other rivers.
It must be noted that Ngai Tahu has signified that they consider there are matters yet to be addressed and they seek the following mitigation:
- In relation to effects on "Mahika Kai", the mitigation sought is:
- An annual trap and transfer programme for the movement of migrants (fish) from upper catchments to the Lower Waitaki.
- A recruitment survey of elvers to monitor the effectiveness of existing elver passes.
- Identification of measures to ensure eel passage beyond Lake Benmore.
- Enhancement of wetland areas for Ngai Tahu management and use.
- In relation to effects on Ngai Tahu relationships with the area:
- Sponsorship of an annual "hikoi" through the Waitaki catchment for members of the three Papatipu Runanga affected.
- In relation to the effect on "mauri" of the waters of the Waitaki catchment:
- Ongoing consultation and an enhanced working relationship between Ngai Tahu and Southern Generation, and a commitment to annual funding of projects.
- In relation to the effect on Ngai Tahu's ability as "kaitiaki" to protect and/or enhance important values and uses:
- ECNZ to identify means whereby Ngai Tahu can be enabled to manage the implementation of mitigation measures in the some way the Department of Conservation does for the Project River Recovery in respect of black stilts.
Finally, the nine "Agreements" include, as background, a statement that ECNZ has "made an undertaking to the Crown to apply for new water rights within 15 years of 1 April 1988". The Interim Development Group understands that this obligation was fulfilled in 1993 by ECNZ.
3.2.1 Agreements
The agreements are as follows, all dated 26 November 1990.
- The "General Agreement" or "Waitaki Agreement" between ECNZ and:
- Her Majesty the Queen (through Department of Conservation).
- South Canterbury Fish & Game Council (Temuka).
- Ngai Tahu Trust Board.
- Benmore Irrigation Company Limited.
- NZ Canoeing Association.
- Mackenzie District Council.
- Lower Waitaki Irrigation Company.
- Maerewhenua District Water Resource Company.
- Morven Glenavy Ikawai Irrigation Company.
- Transit New Zealand.
- South Canterbury Branch of Royal Forest & Bird Society of NZ.
- NZ Salmon Anglers Association;
This agreement included agreed conditions as described above (including a review clause) and recommended that the Canterbury Regional Council adopt these.
- The Agreement between ECNZ and Her Majesty the Queen (through the Department of Conservation)
This document sets out an agreement in relation to habitat improvement in the Waitaki Valley, with the terms of the agreement to be reviewed seven yearly. A substantial sum was required to be paid by ECNZ for the first seven years.
Clause (o) of the document indicates that the goal of the agreement was "providing habitat and conditions equivalent to or greater than the net loss of habitat and conditions attributable to the Waitaki Hydro Electric Power Development".
Clause (m) of this agreement states that:
"ECNZ and the Department of Conservation agreed that a four cumec flow in the Lower Pukaki riverbed would enhance habitat, and the provisions of the agreement are in part in lieu of that flow."
It is not clear what proportion of the mitigation funding relates to this 4-cumec flow.
At the time the agreement was signed a funding arrangement was preferred by ECNZ, over an agreed minimum flow. SISOE needs to review the economic implications of setting a minimum flow, rather than continuing to supply funds under this agreement. As noted, it is not clear which "part" of monies supplied under the first seven-year agreement relates to the 4-cumec flow (clause (m)).
- The Agreement between ECNZ and Transit New Zealand
This document sets out ECNZ's agreement to carry out inspections, and to remedy or prevent lakeshore erosion on Stage Highways 8 and 80.
- The Agreement between ECNZ and Mackenzie District Council
This document sets out ECNZ's agreement to modify culverts and remedy erosion in relation to roads and properties at Lake Tekapo and Lake Pukaki and to advise and consult with the Tekapo Community Board and wider community about lake levels at or below 704.5 m. It also includes agreements relating to tourism advertising and consultation about development of a canoe course.
Tekapo Community Board is concerned about impacts of low lake levels at Lake Tekapo, which can have the effect of making boat ramps inoperable, and the lakeshore area appear unsightly.
The agreement requires an "advisory" and "consultative" role on ECNZ's part and does not set out any obligations to maintain Lake Tekapo at a certain level.
- The Agreement between ECNZ and the New Zealand Canoeing Association
This document sets out an agreement for ECNZ to provide funding for the Canoe Association to design for and implement the enhancement of parts of the Upper Tekapo River for white water recreation.
A canoe course has been completed under this agreement.
- The Agreement between ECNZ and South Canterbury Fish & Game Council
This document sets out ECNZ's agreement to fund the rearing and release of smolt for the period 1991 - 1995, and the Fish & Game Council's commitment to report on the release and effects of the programme. It also sets out ECNZ's agreement to notify the Fish & Game Council of flows more than 150 cumecs below mean flow for May, and advise of operationally induced conditions which could significantly affect the Waitaki fishery.
- The Agreement between ECNZ and Royal Forest & Bird Protection Society of New Zealand Incorporated
This document requires ECNZ to arrange studies in conjunction with the Royal Forest & Bird Protection Society and with the Department of Conservation on the effects of initial spill flow in the Pukaki River on wading birds. It ensures that ECNZ acknowledges the need to strictly comply with operating rules and water right conditions associated with Lake Tekapo lake levels. It also records the Royal Forest & Bird Protection Society' has a particular interest that the seven year review condition attaching to ECNZ's water rights fully consider the issue of Pukaki River flow regimes.
- The Agreement between ECNZ and Benmore Irrigation Company
This agreement relates to the possible extraction of water from the Upper Ohau River by Benmore Irrigation Company. ECNZ has agreed to seek variations to its water rights to dam the Ohau River at the Lake Control Weir, and to maintain a specified minimum flow over a period of abstraction by Benmore Irrigation Company.
(Note: the Benmore Irrigation Company is about to apply for consents for extraction and ECNZ is working through the process at present, in relation to any variations required as per the agreement.)
- The Agreement between ECNZ and the "Lower Waitaki Irrigators" (Lower Waitaki Irrigation Company, Maerewhenua District Water Resource Company Limited, Morven Glenavy Ikawai Irrigation Company)
The agreement sets out a notification system relating to expected flows in the Lower Waitaki River, and an agreement by ECNZ to fund costs to develop inflows to the irrigation system. A twice-yearly consultation programme has also been agreed to.
A minimum flow regime of not less than 120 cumecs has been agreed, with provision for the Canterbury Regional Council to reduce this temporarily, and provide for flow regimes for emergency situations. A "ramping" rate is agreed whereby when the discharge is less than 200 cumecs, the discharge cannot be reduced in any one hour by more than 10%, or by increased greater than 30 cumecs. It sets out that the preferred operating regime is for a constant or only slowly varying flow downstream of Waitaki Hydro Scheme.
- The Agreement between ECNZ and:
- Mackenzie District Council;
- The Department of Conservation;
- Her Majesty the Queen via the Minister of Lands;
- Canterbury Regional Council; and
- Fish & Game New Zealand.
The agreement sets out the land to be vested in the Mackenzie District Council as road, and outlines the contributions to be made by each party for the roads maintenance. The agreement also notes the roads to be maintained by ECNZ.
3.2.2 Summary
The agreements summarised above are additional to the conditions attached to the water rights.
The water rights are valid until 2025. The status of the current review is a "consultative review", and not a statutory review imposed as a water right condition.
3.3 Adequacy of the Existing Resource Consents
In respect of the existing resource consents for the Waitaki Hydro Scheme, the evaluation finds as follows:
- All necessary discharge permits and water permits have been obtained from the Canterbury Regional Council in respect of the Waitaki Hydro Scheme.
- The structures on the beds of lakes and rivers of the Waitaki Hydro Scheme rely on the transitional provisions of the Resource Management Act 1991 ("RMA") [s418 Certain existing permitted uses may continue]. Section 418 states that a resource consent for a structure on the bed of lakes and rivers is not required for any activity lawfully being carried out, until a Regional Plan provides otherwise.
Once the relevant Regional Plan becomes operative, ECNZ will not be able to rely on s418 of the RMA. As such, land use consents under s13 will be required from the Canterbury Regional Council for all structures located on the beds of lakes and rivers (e.g. dams). Therefore it is important that SISOE is involved in the plan development process, through participation in the consultation and submission processes.
Time spent in consultation would be well spent. - The structures on the beds of lakes and rivers of the Manapouri Power Station rely on the transitional provisions of the Resource Management Act 1991 ("RMA") [s418 Certain existing permitted uses may continue]. Section 418 states that a resource consent for a structure on the bed of lakes and rivers is not required for any activity lawfully being carried out, until a Regional Plan provides otherwise.
- Irrespective of the zoning or other provisions of the relevant district planning documents, the continued operation of the Waitaki Hydro Scheme is authorised by the provisions of s10 "Certain existing uses in relation to land protected" of the RMA, provided that the activity is not discontinued and that the effects of the use are the same or similar in character, intensity and scale to those that existed before the rule became operative or the proposed plan was notified. This is likely to be the case for all the components of the Waitaki Hydro Scheme.
Therefore, the only district planning issues relate to s16 Duty to avoid unreasonable noise and s17 Duty to avoid, remedy or mitigate adverse effects. Realistically, given the longstanding nature of the activities at the Waitaki Hydro Scheme, the only potential issue would relate to noise. In this regard, a noise survey was undertaken in March 1996 by Malcolm Hunt Associates who concluded that:
The report recommended that the outdoor alarm point at the Waitaki Station be decommissioned and replaced with an alternative device. This has been carried out. ECNZ is in the process of investigating transformer noise.
3.4 Potential Effects of Operating Plan on the Waitaki Hydro Scheme
The Operating Plan for SISOE sets out a variety of possible changes in river flows and lake levels as a result of the three possible operating strategies.
Set out below are the key environmental issues associated with potential consequences of each strategy. The discussion is sub-divided into three parts, namely, Lake Tekapo, the upper Waitaki area and the lower Waitaki area, as per the Operating Plan. We do not describe the effects where the Operating Plan scenarios indicated "no change".
3.4.1 Lake Tekapo
3.4.1.1 Analysis
Water flows from Lake Tekapo through the 25.2 MW Tekapo A Power Station and the 160 MW Tekapo B Power Station on the shores of Lake Pukaki. Lake Tekapo has a 9 m operating range and a lower limit of 702.1 m. The upper limits vary on a month-by-month basis, from 709.7 to 710.9 m. There are no significant routine operating constraints on Lake Tekapo. From 1 October to 31 March, if the lake level is below 704.1 m, no water can be taken from Lake Tekapo unless Huntly and New Plymouth Power Stations are operating at their maximum.
Highly Aggressive Scenario - Hour-to Hour Changes
The Operating Plan indicates that there may be changes in canal flows on an hour-to-hour basis. A salmon farm is located in the Tekapo-Pukaki canal. Our understanding is that the contracts with salmon farmers do not include any limitations or constraints on flows or levels, with the exception that the canal cannot be emptied except for maintenance. The salmon farm does not require a specified flow rate in order to continue operation.
Highly Aggressive Scenario - Seasonal Changes
The lake will move through a wider range seasonally within the range specified by the consent conditions. Consent CRC 905301 requires lake levels to be returned to above 704.1 m as soon as practicable.
Discussions with the Southern Generation environmental personnel indicate that Tekapo residents and holidaymakers prefer the lake to remain above 707 m in summer (over the period 1 October - 1 March). A level of 706 m is required to allow boat ramp use. Higher lake levels reduce dust generation from the exposed shoreline, and enhance the visual quality of this tourist attraction.
Competitive Scenario - Seasonal Changes
Lake Tekapo may be kept at a lower average level, with similar implications to the aggressive scenario, for other lake users.
Passive Scenario - Day-Night Changes; Seasonal Changes
With potentially higher levels in the lake, and greater spill, the effects on recreational users would be beneficial. However, if lake levels remain high there are potentially higher flood risks as the storage buffer is decreased.
3.4.1.2 Issues Arising
- Lake Level
Maintaining a lake level above 706 - 707m over the summer months is likely to attract comment from the Tekapo community, as the visual quality and recreational usage may be affected.
Lake Tekapo is visibly exposed to the public as Tekapo township is sited on its shores. It is a focus for recreational use while also a well-known beauty spot. The lake could be operated with this in mind and any necessary compensation could be made at Lake Pukaki.
- Operation
The consent condition on CRC 905302 relating to the use of Tekapo unless Huntly and New Plymouth are operating to full capacity is anomalous in a fully competitive environment and where the assets in question are owned by competitors. This requires a legal review. An alternative means of controlling the operation of Lake Tekapo may need to be devised. Additionally, should the Huntly or New Plymouth power stations be mothballed, it may be necessary to renegotiate this condition.
3.4.2 Upper Waitaki, Including Lake Pukaki
3.4.2.1 Analysis
Water flows from the Lake Pukaki Hydro Dam along the Ohau Canal. Water from Lake Ohau also enters this canal, which flows to Ohau A, through Lake Ruataniwha to Ohau B, then via the Ohau-Benmore Canal to Ohau C.
Lake Pukaki has maximum levels of 532 m from September to April, and 532.5 m from May to August. The minimum level is 518.2 m, and the extreme minimum is 518.0 m. The design flood level is 534.1 m. The maximum discharge rate to the Pukaki River is 3400 cumecs. A variety of controls on discharges to the Pukaki-Ohau Canal and Pukaki River are in place.
Highly Aggressive Scenario - Hour to Hour Changes, Day-Night Changes and Seasonal Changes
Under this scenario the Ohau Station would shut down overnight and run by day. On an hour-to-hour and day-to-day basis there would be little change, but the strategy would keep Lake Pukaki lower through the winter and possibly also through the summer.
Currently there is little or no recreational use of Lake Pukaki due to the high turbidity of the water. Its colloidal nature discourages recreational boating and there is little aquatic biota. Our understanding from ECNZ environmental staff is that a proposal to build a holiday village on the shore of Lake Pukaki 2 kms from Gate 18 is in development. Should this occur, there may be pressure to keep Lake Pukaki at a higher level for aesthetic/visual amenity reasons. There are three existing boat ramps on Lake Pukaki, all of which are broken.
Competitive Scenario - Seasonal Changes
No major changes are envisaged on an hour-to-hour, day-night or day-to-to basis, but an overall lower average storage on a seasonal basis is expected. Similar comments to those above apply in this scenario.
Passive Scenario - Higher on Average Level in Lake Pukaki
With higher average lake levels there is the potential for greater erosion around the lakeshore. This is currently dealt with by a condition on consent CRC 905321 which requires precautionary measures to prevent erosion as required by the Canterbury Regional Council, and remedial measures to remedy any damages, as required by Canterbury Regional Council. The lake is a young landform feature and erosion control and repair is likely to be a continuous and ongoing process.
3.4.2.2 Issues Arising
- Lake Level
Long term erosion control and remediation will be required, and this may increase if lake levels are held higher than currently.
- Pukaki River
The black stilt management and rehabilitation project "Project River Recovery" is a programme to which ECNZ contributes funds by agreement with the Department of Conservation. The funding is used in the mitigation for a variety of effects on the Waitaki System, including the loss of a 4-cumec flow in Pukaki River.
It does not appear that the operating scenarios will significantly affect the current flow regime in the Pukaki River, such that Project River Recovery would be affected.
- Lake Ohau and Upper Ohau River
The lake is operated within its natural levels. Minimum flows to the Ohau River are specified in the consent conditions at 8 cumecs in winter and 12 cumecs in summer. An irrigation scheme is proposed by farmers in this area to take 4 cumecs in the summer months. The resource consent process for this matter is currently being worked through, with ECNZ involvement. The new operating scenarios are unlikely to affect this proposed scheme, given the existing consent conditions.
- Lake Ruataniwha
The lake's operating range is around 1 - 1.5 m, with no constraints on its operation. A two-week per year rowing event takes place on the lake that requires a constant lake level and relatively still water. This will continue to require goodwill on SISOE's part.
There is a bird sanctuary in the vicinity.
- Lower Ohau River
The lower river is normally dry. It is known to be a favoured wading bird habitat. The Department of Conservation prefers a large flow in the channel every few years to scour the riverbed, turn the gravels and remove periphyton, weeds, etc. There is likely to be some pressure from the Department of Conservation for a minimum flow similar to that imposed for the Upper Ohau River for the purpose of optimising wading bird habitat and use. This is a matter for the consents review rather than relating to the possible operating scenarios.
3.4.3 Lower Waitaki, Lake Benmore, Lake Aviemore, Lake Waitaki
3.4.3.1 Analysis
Lake Benmore is the largest of the three lakes in the lower Waitaki Hydro Scheme, at 74.5 hectares. Lake Aviemore and Lake Waitaki are 28.8 and 6.2 hectares respectively. Lake Benmore has a normal operating range of 1.05 m, but its wider range is 7.45 m. Lake Aviemore normally operates over a 0.6 m range, with a full range of 3.95 m. Lake Waitaki has a normal operating range of 2.1 m, with a full range of 7.5 m.
Highly Aggressive Scenario - Hour-to-Hour, Day/Night and Day-to-Day Changes
The effects of an aggressive operating strategy in the Waitaki Hydro Scheme would be seen in storage levels at Lake Benmore and in flow rates on the Waitaki River. There may be fluctuations between night and day and between weekdays and weekends.
Competitive Scenario - Day/Night Changes
These would be less significant than those for the highly aggressive scenario.
Passive Scenario
No changes identified.
3.4.3.2 Issues Arising
- Lake Levels
Lake Benmore is very popular for recreational boating and fishing, and commercial tourist fishing operators use the lake. Camping around the lakeshore is popular, particularly at Sailors Cutting. Lakes Aviemore and Waitaki are also used recreationally. Rapidly rising lake waters can affect the use of the camping ground as the risk of campsite flooding increases. Campers like to camp as close to the water as possible. This can be a particular problem at Lake Aviemore.
No significant erosion issues have been identified at Lake Benmore. A more aggressive regime could exacerbate erosion in the Lake Aviemore area. Consultation with Transit New Zealand and/or the Mackenzie District Council regarding erosion remediation may be required. Some shoreline erosion at Te Akatarawa Road already occurs and is subject to remediation by ECNZ.
- Waitaki River Flow Rates
A minimum flow rate of 120 cumecs is required in the Waitaki River below Benmore as a condition of consent CRC 905360. A discharge flow ramping rate applies at flows less than 200 cumecs, with specified rates allowed under increasing and decreasing river flows. ECNZ voluntarily limits ramping rates to those required at flows less than 200 cumecs even when flows are greater than this. Our understanding is that the existing minimum flow is considered acceptable as a minimum, though it is likely that interest groups would prefer a minimum of 150 cumecs to improve fish spawning.
Monitoring of minimum flows by ECNZ is continuous, and the minimum flow level is rarely applied. ECNZ tends to operate above 150 cumecs as a self-imposed minimum to minimise concerns from the conservation organisations.
Erosion is an ongoing issue in the lower Waitaki River valley. Water right conditions require ECNZ to take precautionary measures to avoid erosion, and to provide such remedial repairs as the Canterbury Regional Council requires. Currently ECNZ makes an annual contribution to the Canterbury Regional Council, which maintains an erosion fund. The Canterbury Regional Council utilises this fund to carry out annual repairs and undertake preventive works at erosion "hot spots".
Floods and flow variation are natural events in a system such as the Waitaki River, which has a very large unforested upland catchment. The effect of the dams within the system causes faster, shorter floods, rather than the longer slower floods that would occur naturally. There appears to be general acceptance that the existing operating regime is being managed appropriately to minimise flooding. However, the Lower Waitaki River Rating Group, members of which were affected by floods in 1995 may wish to see the dams used more proactively for flood control.
The Canterbury Regional Council currently monitors around 20 cross-sections of the river, on a five-yearly basis.
A change to the operating scenario that causes more rapid fluctuation in the lower river than occurs at present, may increase erosion downstream. If significant additional erosion were to occur, this may require renegotiation of monitoring and remediation budgets currently paid to the Canterbury Regional Council.
The hydrological consequences of adopting the aggressive and competitive scenarios need to be carefully evaluated in detail to ascertain whether and to what extent they move outside the current situation. If the hydrological consequences were significantly different, discussion with the Canterbury Regional Council would indicate whether additional monitoring (either in frequency or in number of profiles) should be undertaken. While this is not required by consent conditions, it would benefit the good working relationship currently held between Southern Generation and the Canterbury Regional Council, which SISOE wishes to build on.
3.5 Relationship with Regulatory Authorities
As part of this review, a meeting was held with management staff from Canterbury Regional Council. This meeting indicated that a good working relationship had formed between ECNZ and staff of the Canterbury Regional Council and that ECNZ was held in high regard. In addition, it was also noted that the Canterbury Regional Council considered the term of the existing consents were appropriate; the level of compliance was considered to be excellent; and any outstanding issues were considered minor and of no particular significance.
3.6 Potential Environmental Effects After SISOE Split
Our understanding is that the operation of the Waitaki Hydro Scheme is unlikely to change under SISOE management. However, if the operating scenario were to change, the hydrological consequences would require careful evaluation.
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