U:\2021\BM210482_IBo_Waihi_North_Project\Documents\WNP_Freshwater_Report_May_2022\FINAL_Freshwater_Report_FOR DELIVERY_June 2022\FINAL DELIVERED 17 JUNE 2022\WAI-985-000-REP-LC-0007_Rev0_Freshwater_20220621_FINAL.docx • Streamworks should ideally be undertaken offline or should be isolated with water pumped around the area of works. • Ensure material from vegetation removal does not enter the stream. 22.3 Stream reclamation Across the footprints of works for WNP there is an overall expected loss of some 3,941 m of low to high value stream loss (Table 47) as well as some 9 m2 of warm spring. This is to be offset with the creation of 10,178 m of stream diversion channels and stream restoration. With the exception of the warm spring, the offset has been calculated through an Ecological Compensation Ratio (ECR) but the outcome equates to an approximate 2.6:1 offset ratio (gain:loss). 22.4 Stream offset calculations The ECR has the underlying principle of ‘no net loss’ and is based upon ‘no net loss of areaweight stream function’. A minimum quantum of offset of 1:1 is expected. For the loss of the warm spring, we have provided a ratio-based compensation based on the aquatic attributes. 22.5 ECR multiplier For WNP a multiplier of 1.0 has been applied in the calculation of the ECR (the standard application of ECR recommends a multiplier of 1.5). The use of this lower multiplier is justified for the following reasons: • The WNP results in no actual permanent loss of streams. Streams are either replaced within a short timeframe (functional diversions) or returned and rehabilitated at a later date (Mataura Stream tributary 2). • The overall condition and health of these final watercourses will be an improvement upon those currently present. • The residual effect on streams is limited to a timeframe rather than a permanent loss. • A large extent of stream diversions and stream offset restoration works can be commenced and undertaken prior to any stream loss. This significantly reduces any time lag factor. • The replacement streams (diversions) contain the same source water and retain the same connectivity with their respective upper catchments (i.e., the offset is not at a different location). • OGNZL has a successful track record of successful stream restoration work within the OGNZL owned land and around the Waihi area. • OGNZL has undertaken extensive stream restoration works, particularly on the Ohinemuri River and Ruahorehore Streams, already improving the ecological function of the watercourses. This has never previously been accounted for in any mitigation (and for clarity these existing restoration works are not being utilised in this application).
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