Appendix 3: Methods for Assessment of Stream Freshwater Ecology Boffa Miskell Ltd | Waihi North Project: Freshwater Ecological Assessment | Field Methods There was variability in the field methods employed across different areas of the Waihi North Project. The three areas of ‘Wharekirauponga’, ‘Willows Farm’ and ‘Waihi’ all contain different freshwater environments. Wharekirauponga Stream and Tributaries General stream habitat information such as water depth, stream width, stream substrate composition, riparian characteristics and were recorded based on a modified Department of Conservation Stream habitat assessment – field sheet. Water quality was recorded utilising a handheld meter (YSI multi-parameter water quality meter) and will measure dissolved oxygen, pH, conductivity and temperature. The readings were be taken at the beginning of the survey, at the downstream extent of the survey reach. Periphyton communities were assessed for their cover and community cover using the methodology outlined in Gray (2013a). This method involves visual assessment of the periphyton growth on five rocks (i.e. cobbles) at each of three transects across the watercourse (i.e., n = 15). Periphyton community assemblages will be assessed using the methodology outlined in Gray (2013b). This method involves removing the periphyton community off streambed rocks (i.e. cobbles) and preserving it for later analysis in a laboratory. Known area surface sample method was undertaken. Gray (2013b) stipulates the collection of three pooled samples (each from five rocks) collected from each sample site. six pooled samples were collected There are two variations on this method; whole stone surface sample or known area surface sample. The final method will be decided on site depending on the size and availability of rocks within the survey reach. as this aligns with the programme undertaken on the Ohinemuri River as part of the ongoing OceanaGold Waihi freshwater monitoring. Macroinvertebrate communities were assessed through the collection of replicate, quantitative samples following Protocol C3 as described in Stark et al (2001). Six replicate samples were collected at each site using a surber sampler. Samples were processed using Protocol P3, which is a full count of all species, with a subsampling option (Stark et al 2001). Fish communities were surveyed by electric fishing, following the methods outlined in Joy et. al. (2013). The method includes using a NIWA Kainga300 backpack mounted fishing machine to stun fish within the survey reach. The stunned fish are collected and held in bins of freshwater on the river bank. All fish area identified, measured and checked for general health before being returned to the watercourse. Reaches of 75m were fished owing to the challenging nature of the sites. Willows Farm Fieldwork to assess the first impact site and the Mataura Stream was conducted on the 20th and 21st of July 2020. Weather conditions were predominantly fine, with some 16mm of rain on the afternoon of the 20th. There was approximately 55mm of rainfall over the seven days prior to the fieldwork. Further fieldwork was conducted at two potential water take sites within the Waiharakeke Stream catchment on 26th of August 2020. Weather conditions during site visit were overcast with minimal wind. There was approximately 16mm of rainfall during the 48 hours before conducting the site assessment and just over 40mm of rainfall over the previous seven days.
RkJQdWJsaXNoZXIy MjE2NDg3