Erosion and Sediment Control Assessment Report Rev. 0 This is an uncontrolled copy if photocopied or printed from the Intranet. Copyright © 2016, SouthernSkies Environmental Ltd. All rights reserved. Page 12 of 30 • Small tributary watercourse has moderate ecological function. • Assessed using the EIANZ criteria as having moderate ecological value. Northern Rock Stack4 • A wetland feature occurs within the TB1 stream corridor at TB1-1c. This wetland has been formed from a former silt pond that was developed as part of the construction of the tailings storage facility (TSF2). • Overall, streams within the NRS footprint are considered to be of moderate ecological value. The streams are historically highly modified with streambeds smothered by fine sediment; partially a result of their predominantly pasture catchments. Macroinvertebrate communities were dominated by tolerant taxa, while the presence of EPT taxa was relatively low. Fish fauna were sparse, with only shortfin eel species recorded during the surveys. • The streams within the NRS footprint are not considered significant under the RPS Section 11A criterial. The tributaries within the NRS footprint were classified using the EIANZ criteria outlined in Table 1 and we considered both sites to have ‘medium’ ecological value (Table 20), Tailings Storage Facility 35 The freshwater ecological values across the Ruahorehore Stream catchment are varied with a mixture of permanent waterways, vegetated drains and water collection ponds (Error! Reference source not found.). 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 macroinvertebrate communities present are diverse with the pollution sensitive EPT taxa present at all sites, but communities are dominated by those species that are more pollution tolerant. Ecological values of the Ruahorehore Stream within the proposed TSF3 footprint are of moderate (RUA_Upper) and high (RUA_Forest) ecological value. Diverse macroinvertebrate and fish communities are present and include the presence of freshwater crayfish and longfin eel (At Risk – Declining). Table 2: Sediment retention device receiving environments. Site Receiving Environment Comments Willows Road Site Unnamed tributary and Mataura Stream (Ohinemuri tributary). Runoff will be treated by ESC measures that will discharge overland and via drainage channels to an unnamed tributary, approximately 1km channel length upstream of the river. Services Trench Ohinemuri River. The trench alignment will cross various overland flow paths and drains that fall towards the river. It will also require services crossing of the river at Willows Road and State Highway 25. 4 Ibid; Section 11.0 5 Ibid; Section 10.0
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