4 OGNZ WUG mine: assessment of potential ecological effects Project 2034 SeeAttachment C for key tables from the EIANZ guidance that we have used to assess magnitude, values and level of potential adverse effect. Added to this, we have provided context in terms of our opinion on the likelihood of an adverse effect occurring at the site, given the controls in place and our experience with the subject site. Table 2 (andTable 1) provides a summary of the activities or aspects of the WUG that may result in adverse effects on Archey’s and Hochstetter’s frogs. The initial description we provide of the potential adverse effects associated with each activity does not include any actions to manage those effects. For each activity or aspect inTable 2(andTable 1) we go on to provide our assessment of the potential level of adverse effect after adoption of the avoidance and mitigation measures that OGNZL has agreed to adopt as part of the WUG design and as are recorded in the proposed conditions of consent. Values and magnitude have been assessed according to Tables 5, 6 and 8 in the EIANZ framework (see Attachment B). Level of effect is assessed using a risk matrix approach as per Table 10 of the EIANZ guidance. A level of effect that corresponds to Moderate, High or Very High is generally accepted by ecologists to constitute a ‘significant ecological effect’ under the RMA, while a Low or Very Low level of effect is usually considered to correspond to a ‘minor ecological effect’ or ‘less than minor ecological effect’ under the RMA. It is usual for a ‘Very High’ level of effect to trigger re-design or avoidance. The level of effect presented inTables 1 and 2 may change if additional technical information is provided to us, especially where it includes additional measures to avoid or reduce the magnitude of adverse effect, or where effective mitigation is provided to further minimise the severity of effect. The level of effect concluded inTables 1 and 2 is after efforts to avoid, remedy or mitigate have been applied (that is, for clarity, magnitude of effect is assigned after to the application of avoidance/ mitigation measures). The ecological values of Archey’s frog and Hochstetter’s frog are scored as ‘High’, following the criteria listed in EIANZ Table 5 when considering species with an ‘At Risk -Declining’ threat classification. Where an activity may result in a loss of Archey’s or Hochstetter’s frogs, we have considered that the potential loss of a small number of frogs constitutes a ‘low’ magnitude of effect. This differs from the opinion that was given by all experts at the start of this exercise in 2021 where we had followed the approach where, although both Archey’s and Hochstetter’s frogs are classified as ‘At Risk – Declining’, and their populations appear to be stable within Coromandel Forest Park, we speculated that mortality of even a small number of individuals could have a high magnitude of effect. The key reasons for the change from considering some potential loss of frogs from being a ‘high’ magnitude of potential effect to ‘low’ magnitude is because: 1. Work by Dr Lloyd for this project analysed measured Archey’s frog densities across different habitat types and elevations and from that analysis estimated the likely population size for Archey’s frogs in the Coromandel (not including elsewhere and not including a substantial area of the Coromandel for which information on Archey’s frog presence is unknown). That work indicates that our best estimate for the total Coromandel Archey’s frog population is 54.8 million frogs6. This is substantially greater than our original assumptions of population size, which was based on DOC’s estimates of between 5,000 - 20,000 mature individuals for the national population7. The work by Dr Lloyd for this project indicates that a conservative (high) estimate is that Archey’s frogs living within the potential disturbance area of the WUG comprise 0.53 % to 0.58 % of the total Coromandel population, and that area of habitat involved is 0.54 % of the total area of Archey’s frog habitat available within areas where frogs are currently known on the Coromandel (this excludes a very large area of the Coromandel potentially also occupied by Archey’s frogs but for which there are no records in the national database, and also excludes two other Archey’s frog populations fromWhareorino and Pureora Forest Park); and 6 Lloyd, B. 2022. Estimating the proportion of the Coromandel’s Archey’s frog population in the area affected by vibrations from the proposed Wharekirauponga Mine. Report prepared for OGNZL. 26 May 2022. 7 DOC Threat Classification listing qualifiers.
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