Appendix 3: Methods for Assessment of Stream Freshwater Ecology Boffa Miskell Ltd | Waihi North Project: Freshwater Ecological Assessment | Further habitat assessments were only undertaken on those watercourses that were classified as perennial, or permanent. Stream Ecological Valuation The SEV is recommended by Auckland Council for providing an ecological valuation of streams and is increasingly being used outside of Auckland. The SEV uses a set of fourteen qualitative and quantitative variables to assess the integrity of stream ecological functions (Table 1). Field work consists of a comprehensive assessment of the in-stream and riparian environment. This includes a fish survey, aquatic macroinvertebrate sampling and cross-sections of the stream to measure width, depth and substrate, as well as using qualitative parameters for reach-scale attributes. Table 3-1: Summary of the 14 ecological functions used to calculate the SEV score. Hydraulic functions: Biogeochemical functions: Processes associated with water storage, movement and transport. • Natural flow regime • Floodplain effectiveness • Connectivity for species migrations • Natural connectivity to groundwater Relates to the processing of minerals, particulates and water chemistry. • Water temperature control • Dissolved oxygen levels maintained • Organic matter input • In-stream particle retention • Decontamination of pollutants Habitat provision: Biotic functions: The types, amount and quality of habitats that the stream reach provides for flora and fauna. • Fish spawning habitat • Habitat for aquatic fauna The occurrences of diverse populations of native plants and animals that would normally be associated with the stream reach. • Fish fauna intact • Invertebrate fauna intact • Riparian vegetation intact This data is analysed using a series of formulae in order to produce an SEV score of between 0-1, where a 0 is a stream with no ecological value and 1 is a pristine stream with maximum ecological value. Interpretation of SEV scores is given in Table 4 below. Table 3-2: Interpretation of SEV scores (Adopted from Golder Associates, 2009). Score Category 0 - 0.40 Poor 0.41 – 0.60 Moderate 0.61 – 0.80 Good 0.81+ Excellent Ecological Compensation Ratio
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