52 10.2.1.4 Fish Communities Fish populations present at site RUA_revegetated contained an abundance of common bully (n= 90) . Shortfin eel and kōura were also present. Fish populations at site RUA_lower had an abundance of shortfin eel with at least 30 individuals present; predominantly living within the macrophyte. Kōura, a common bully and a rainbow trout (Oncorhynchus mykiss) were also present. Site RUA_upper was home to a large longfin eel over 1.1 m in length. Longfin eel are classed as At Risk – Declining (DOC 2018a). In addition, three shortfin eels and five kōura were present. Kōura were abundant at site RUA_forest with over 60 individuals recorded. A longfin eel and a shortfin eel were also recorded. A waterfall located between site RUA_upper and site RUA_forest represents a significant barrier to fish passage of swimming species. Fish populations at site RUA_Trig Road were poor with only shortfin eel recorded. 10.2.1.5 Stream Ecological Valuation SEV scores ranged from 0.4 (RUA_Trig_Road) to 0.85 (RUA_Forest), thus ranging from poor to excellent stream functionality. As might be expected SEV scores were highest in the upper catchment and scores were lowest in the lower catchment, including the Trig Road site (RUA_Trig_Road). The key driver of the SEV is the presence of riparian vegetation as well as the retention of more natural attributes notably within the forested and upper sections of the stream. As for the SEV descriptions for the Mataura Stream catchment, the SEV scores for the Ruahorehore Stream occur within the range reported for forested and rural streams (WRC 2020, AC 2011). The individual SEV attribute scores for each site on the Ruahorehore Stream are provided in Appendix 5. 10.2.1.6 Vegetated Drains Ruahorehore Numerous drains intersect the farmland within the proposed tailings and rock disposal area. These drains contain substantial volumes of flowing water, and evidently work to lower the water table sufficiently to have enabled pastoral conversion of wetlands likely to have been once present throughout areas of low-lying land. The margins of these drains are predominately vegetated with rank grass, exotic herbs and exotic trees and shrubs including: Spanish heath, pampus, blackberry, gorse, Chinese privet and crack willow. The incised stream banks however are generally well-vegetated in native ferns such as wheki (Dicksonia squarrosa), kiokio, ring fern (Paesia scaberula) and bracken (Pteridium esculentum). These vegetated drains provide habitat to freshwater macroinvertebrate and fish species, functioning in a similar manner to natural streams. In particular, they provide fish passage from the Ruahorehore Stream to the forested headwaters of the sub-catchment. 10.2.2 Summary The freshwater ecological values across the Ruahorehore Stream catchment are varied with a mixture of permanent waterways, vegetated drains and water collection ponds (Table 19). The Ruahorehore Stream, both adjacent to and downstream of the proposed TSF3 is a highly modified habitat of generally moderate-poor quality. Riparian vegetation is limited (except at site RUA_forest within the SNA) with excessive macrophyte growth common. The
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