by Gavin Kemble, Environmental Manager, Trustpower.
1.
Physical Methods
Chemical Methods
Cultural and other management methods
Yours faithfully,
Gavin Kemble
Return to:Thank you for giving TrustPower Limited ('TPL') the opportunity to comment on the contents of your article titled "Mahinerangi, A Lake in Danger. The Price of Chemical Spraying".
We are unaware of any operating regime for Lake Mahinerangi being agreed by the previous owners (Dunedin City Council) of the Waipori HEPS as stated in Paragraph 3 of your article. In this respect, we understand that Dunedin City Council utilised the water within Lake Mahinerangi without restriction and, as a consequence, employed a ten (10) metre operating range. As you are aware, TPL is proposing to halve this operating range to five (5) metres under normal conditions.
2.
It is inaccurate to imply that the environment and efficiency come second to TPL's need to maximise profits. In this respect, TPL is committed to ensuring that its operations do not induce significant adverse environmental effects. This is evidenced by the time and resource being committed by TPL in researching the environmental issues raised by the stakeholders during the reconsenting process. As previously indicated if this research highlights that significant adverse environmental effects are being induced appropriate mitigation measures will be developed and implemented.
3.
As you are also aware, TPL is in the process of maximising the efficiency of the Waipori HEPS. In this respect, it is in no ones best interest to employ inefficient plant. While the preparation of the 'Lake Mahinerangi Weed Management Strategy' was funded by TPL, it was never intended that this document would apply solely to the lakebed and riparian margins administered by the Company. In this respect, and in response to comments made by stakeholders at the first 'Weed Management Meeting' (being the meeting held on the 7th of February 2000) a more 'holistic', catchment wide approach has been adopted. A catchment wide approach was adopted as it was felt that this would provide a sustainable, long-term solution to the weed problem apparent within and adjacent to the lake, and indeed within the entire catchment. All at the meeting agreed that this would not be achieved were the Strategy to focus only on the land under TPL's control and/or administration.
4.
It is for the above reason that the Strategy recommended that TPL contribute in the order of $66,000 (over a five (5) year period) for the control of weeds. In this regard, it was felt that this amount would be needed to control and (where appropriate) eradicate the gorse and broom existing on the land administered by TPL. The $351,000 referred to in Paragraph 11 of your article is the estimated cost of weed control within the whole Lake Mahinerangi Catchment. While TPL accepts that it must address the weeds present on its land, it does not accept that it should also be responsible for weed control on land owned and utilised by others.
As stated by Mr Harris and Dr Ryder at the second Weed Management Meeting (being the meeting held on the 26th of May 2000), a 'tool box' of possible methods for gorse and broom control is promoted within the draft Strategy. This statement is supported by Section 8 of the draft Strategy which recommends that the following methods of gorse and broom control be used in Lake Mahinerangi's catchment:
5.
Dozer and Excavators
Hand clearing manually
Use of fixed wing plane and helicopter
Using other methods
Use of pellets
Flooding land area
Stock grazing sheep/oversowing
Subdivision fencing
Plant competition using shrubs and trees
While Section 12 of the draft Strategy does indicates that the application of approved herbicides should be the dominant form of weed control, we understand that this recommendation was made on the basis of the proven cost and control effectiveness of this method, and not, as implied by your article, because it was the most suitable option for TPL. The somewhat bleak picture painted in Paragraph 12 of your article (being that the Draft Weed Management Strategy will result in an environmentally degraded 'dust bowl') is, in our opinion, incorrect. This statement contradicts the advice provided by the reputable and respected weed management consultants and ecologists that prepared the draft Strategy.
6. The statement made within Paragraph 15 of your article that methods of control, such as the planting of trees and native grasses were not costed in the Draft Weed Management Strategy because they would "interfere with TrustPower's operating regime…" is inaccurate. We understand that these methods of control were not costed because the necessary data was not available at the time when the Strategy was prepared.
7. While we accept that a request was made for TPL to monitor the effect of inundation on gorse and broom, your statement that such a request was 'refused' is mis-leading. In this respect, TPL stated that it would commission such work if, once it had been considered by those who attended the second Weed Management Meeting, it was generally accepted by the stakeholders as being required. We note that this issue was raised at the aforementioned meeting but did not receive strong support (other than by Ms Joel and yourself). As a consequence, no further work has been commissioned on this matter. We are, however, willing to revisit your proposed investigation at the next Weed Management Meeting.
8. The statements made within Paragraph 15 of your article that "[TPL] said that periodic inundation was not an option for them…" and that "They [being TPL] also said that such control methods would not be supported by other stakeholders" are false and misleading. Such statements were never made by TPL or its representatives.
9. Lastly, Paragraph 16 of your article suggests that TPL are committed solely to the use of herbicides to control gorse and broom. This is incorrect. The precise methods of control will be determined in conjunction with the other members of the 'Steering Committee' established (at the second Weed Management Meeting) to implement the Weed Management Strategy.
Environmental Manager
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