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Biomonitoring of streams associated with Henty Gold Mine 2006 Report to Henty Gold Mine, Placer Dome Asia Pacific.


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Davies, PE ORCID: 0000-0003-2651-4061, Cook, LSJ and Sloane, T 2006 , Biomonitoring of streams associated with Henty Gold Mine 2006 Report to Henty Gold Mine, Placer Dome Asia Pacific..

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The following report details the findings of biological monitoring performed in 2006 in streams associated with the Henty Gold Mine. This represents the 14th year of biological monitoring of two sites in the upper Henty River and one in a tributary of Newton Creek. This monitoring program involves the annual quantitative and semi-quantitative sampling of benthic macroinvertebrates in riffles (sections of fast, broken or chaotic flow over a cobble substrate), as well as the quantitative sampling of fish. The same set of sites has been sampled in the same season (usually autumn-early winter, late February to June), with only minor variation, each year. Sampling in 2006 was conducted in late May. The program samples an upstream (‘control’) site in the Henty River and two potentially affected (‘treatment’) sites, one downstream of the point of mine water discharge from the artificial wetland complex in the Henty River, and the other downstream of the leach residue pond emergency spillway overflow into a tributary of Newton Creek.

This report represents the 2006 annual update of the entire monitoring program from its inception, and has been written so that the reader does not necessarily have to refer to previous reports (Davies 1995, Davies and Cook, 1998-2000, 2001-2002, 2003, 2004, 2005).

Emissions from the Henty Gold wetland wastewater treatment facility into the Henty River commenced in 1996. The use of the same sampling methods throughout the monitoring program from 1993 to 2006 allows comparisons to be made between sites and years. The study design, based on both standardised quantitative and semi-quantitative sampling, is also robust to changes in sampling personnel. In this report, comparisons are made between yearly sample data derived from pooled Surber sample units. The primary variables used for these comparisons are: total abundance, number of taxa and the abundance of individual orders and/or families of macroinvertebrates. Trends in community composition and compositional similarity to control site are also evaluated, using a control-chart approach.

Both quantitative (‘Surber’) and AUSRIVAS rapid assessment protocol (RAP) sampling of stream macroinvertebrates are conducted at Henty Gold Mine. Surber sampling provides a detailed, quantitative assessment of impact specific to Henty Gold Mine’s operations, while AUSRIVAS sampling allows semi-quantitative assessment results to be reported in the context of other sites in the region and the entire state if required. Both of these methods are recommended in the ANZECC (2000) water quality monitoring and reporting guidelines.

Fish sampling has also been conducted, by electrofishing, at each Henty River site. Since other factors may also determine the abundance and presence of fish in the upper Henty (spawning success and stocking of the storage downstream), the presence of fish juvenile and adults is reported and no further data analysis is conducted.

Item Type: Report (Technical Report)
Authors/Creators:Davies, PE and Cook, LSJ and Sloane, T
Keywords: Tasmania, streams, freshwater, Henty Gold Mine
Publisher: Freshwater Systems
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