78 • Periphyton was dominated by diatoms followed by filamentous algae. • Algal standing crop or biomass was below the thresholds set out in the NZ Periphyton guidelines and in spring 2021 median Chl-a levels were below the NBL for ecosystem health (aquatic life) for periphyton. • Macroinvertebrate community Index scores (QMCI and MCI) show the Ohinemuri River to range from poor to fair and varies between Attribute C and below the NBL of the NOF for ecosystem health (aquatic life). • No statistical difference in macroinvertebrate community indices and attributes upstream and downstream of the WTP discharge to the Ohinemuri are evident • Shortfin eels and common bullies were the most widespread and common species recorded during monitoring, but longfin eels, Cran’s Bully, and rainbow trout were all recorded during monitoring surveys. Banded kokopu have been recorded in earlier surveys. • The Ohinemuri River is classified as a significant trout fishery. • Overall ecological values are moderate. 13.6.9 Summary of Ecological Condition of the Ohinemuri River In summary, in the mid-lower reaches of the Ohinemuri River, indicators of ecological condition suggest moderate ecological values, and values increase towards the headwater areas. There is no evidence that discharges associated with mining activities at Waihi have an adverse impact on the ecological values of the Ohinemuri River, and the benthic periphyton and macroinvertebrate communities have not varied greatly over the period of monitoring. This suggests that the ecological values of the Ohinemuri in the vicinity of the Waihi mining operation have not changed. It is worth noting, that the Ohinemuri River catchment is not identified as a priority catchment or as an outstanding freshwater body (although the Waihou River at Whites Road is listed to be included as outstanding) in the RPS (section 8.2.1). 13.7 Summary of Ecological Values In this section we summarise each of the WNP elements based on our assessment applying the EIANZ criteria, and our assessment of significance for indigenous biodiversity (based on RPS significance criteria). The overall assessment for each habitat or ecological attribute is summarised in Table 25.
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