Supporting Technical Assessments

GHD | Oceana Gold New Zealand Ltd. | 12552081 | Waihi North Project 68 6.3.7 Seasonal Ohinemuri River Water Quality The predicted water quality fluctuates seasonally. As a large proportion of the mass going through the WTP is from the WUG operations and is modelled as constant throughout the year, in-stream concentrations increase over the summer months (while remaining compliant) as the dilution of the treated water becomes less. This is illustrated for manganese and zinc in Figure 50 and Figure 51 respectively for the modelling year 2027. A similar pattern is evident in most of the consented trace elements. Figure 50 Predicted manganese concentrations at OH6 over 2027

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