The ephemeral Saga and Inca channels are characterised by low banks (predominantly <1.5 m high), a meandering planform, and bedload material consisting of unconsolidated sands and gravels, which are typical of the rivers of this region (cf. Taylor and Hudson-Edwards, 2008). The adjacent floodplains are relatively uniform alluvial surfaces with no evidence of significant incision and terrace formation. Finer alluvial sands and silts comprise these surfaces, with occasional small gravels. Although the channel and floodplain contain native vegetation

(eucalypts), it is generally sparse, which see more is a function of the semi-arid climate as well as cattle grazing. The study area is situated within the Lawn Hill Subprovince of the greater Mount Isa Inlier, with the basement sequence comprising Proterozoic sedimentary, volcanic and intrusive rocks; metamorphosed regionally and folded by the Barramundi

Orogeny (Page and Williams, 1988). Key cover sequences comprise mainly fluvial and shallow marine sedimentary deposits with some volcanics that include the primary ore bearing deposits for many of the Cu and Pb–Ag–Zn mines within the area (Derrick, 1982). AG 14699 The Lady Annie ore body is part of a key unit within these deposits known as the greater McNamara Group (Page and Sweet, 1998), which is characterised by dolomite, siltstones and quartzo-feldspathic sandstone. Chalcopyrite (CuFeS2) and pyrite (FeS2) occur in the coarse grained carbonate breccia of the primary ore body. The overlying oxidised zone comprises primarily of copper minerals such as cuprite (Cu2O), chalcocite (Cu2S), bornite

(Cu5FeS4) and malachite (Cu2CO3(OH)2) (Cavaney, 1975 and Van Dijk, 1991). The Saga and Inca creek catchment lies across the McNamara Group and the younger Georgina Basin, which is composed of Cambrian limestone, dolomite, conglomerate, sandstone, siltstone and chert of the Georgina Basin as well as Cainozoic surface alluvial and colluvial sediments (Denaro et al., 2001 and Grimes et al., 1998). Agriculture, predominantly cattle grazing, is the most extensive land use within the catchment with 330 pastoral holdings, which includes the Yelvertoft cattle station (Fig. 1) (Lake Eyre Basin Coordinating Group, 2000). Since 2011, the Georgina and Diamantina catchments of the Lake Eyre BCKDHB Basin have been protected under the Wild Rivers Act 2005 (Queensland; Queensland Government, 2013). The Lady Annie Project, starting in October 2007, is a Cu heap leaching operation involving open pit mining of the Cu oxide deposits with all processing carried out at a central plant located within the upper reaches of the Saga and Inca creek catchments (Fig. 1; Australia’s Identified Mineral Resources, 2009 and Snowden Mining Industry Consultants, 2010). Residual waste is held in two main storage ponds at the processing plant and includes water, sulphuric acid and fine rock.