Stygofauna Values at the Lake Disappointment Potash Project Prepared for: Reward Minerals Limited October 2018 Final Report Lake Disappointment Stygofauna Reward Minerals Limited Stygofauna Values at the Lake Disappointment Potash Project Bennelongia Pty Ltd 5 Bishop Street Jolimont WA 6014 P: (08) 9285 8722 F: (08) 9285 8811 E: [email protected] ABN: 55 124 110 167 Report Number: 304 Report Version Prepared by Rev iewed by Submitted to Client Method Date Draft Anton Mittra Stuart Halse email 7 July 2017 Final Anton Mittra Stuart Halse email 27 July 2017 Final V2 Anton Mittra Stuart Halse email 22 September 2017 Final V3 Anton Mittra email 25 October 2017 Stuart Halse Final V4 email 15 October 2018 Anton Mittra BEC_Lake Disappoint m ent Stygofauna Final_V4_8x18.docx This document has been prepared to the requirements of the Client and is for the use by the Client, its agents, and Bennelongia Env ironmental Consultants. Copyright and any other Intellectual Property associated with the document belongs to Bennelongia Environmental Consultants and may not be reproduced without written permission of the Client or Bennelongia. No liability or responsibility is accepted in respect of any use by a third party or for purposes other than for which the document was commissioned. Bennelongia has not attempted to verify the accuracy and completeness of information supplied by the Client. © Copyright 2015 Bennelongia Pty Ltd. i Lake Disappointment Stygofauna Reward Minerals Limited ii Lake Disappointment Stygofauna Reward Minerals Limited EXECUTIVE SUMMARY Reward Minerals Limited is currently seeking approval to develop the Lake Disappointment Po tash Project (the Project), approximately 138 km south of Telfer and 285 km east of Newman in the northern Little Sandy Desert. The Project will require groundwater abstraction from two proposed borefields and therefore has the potential affect any stygofauna habitat, as well as species and communities, that occur there. Desktop review of a 100 km by 100 km area surrounding the Project found no records of stygofauna, but also no evidence of any survey having occurred, so the search area of the review was expanded to include the nearest known stygofauna communities. At least 97 species of stygofauna have been recorded in the extended search area, including nematodes, rotifers, gastropod molluscs, annelid worms, crustaceans (ostracods, copepods, syncarids, amphipods, isopods) and hexapods. Potential stygofauna habita ts in the vicinity of the Project are alluvial, colluvial, fractured sandstone and calcrete aquifers. There are two proposed process water supply borefields: the Cory Borefield will target the Gunanya sandsto ne fractured rock aquifer and the Northern Borefield will target the deeper units of the Tertiary cover sequence of sands, clays and sandy clays that overlies the Proterozoic basement. Regional calcretes will not be targeted for groundwater abstraction and are unlikely to be affected by drawdown. A field survey that collected 30 samples from 15 sites (10 in proposed borefields and five from the surrounding region) confirmed the occurrence of stygofauna in the Project area, with 300 specimens of 13 species being collected. Sixteen out of 30 samples and 13 out of 15 sites yielded stygofauna, althoug h two regional sites yielded only rotifers, nematodes and a very widespread cyclopoid copepod. Major groups recorded include oligochaetes, amphipods, syncarids, cyclopoid and harpacticoid copepods, and ostracods. The Cory Borefield appears to host more stygofauna tha n the Northern Borefield and the assemblages in the two borefields appear to be distinct from one another. Overall, the documented stygofa una community at La ke Disappointment is modest compared with many areas of the Pilbara and Yilgarn. Neither borefield appears rich in stygofauna. Six of the stygofauna species collected are currently kno wn only from the La ke Disappointment area. The distributions of two of the six species, Tubificidae sp. B03 (LD) and nr Pilbar us sp. B07, are locally extensive and include areas outside the proposed borefields and predicted zones of groundwater drawdown. While the o ther four species are known only from inside the proposed borefields and/or zones of predicted drawdown, it is likely that they also have more extensive ranges because of likely habitat connectivity. The locally extensive ranges of species such as the worm Tubificidae sp. B03 (LD) and amphipod nr Pilbarus sp. B07 support the no tion that other species known only from the boefields are likely to be locally widespread. iii Lake Disappointment Stygofauna Reward Minerals Limited CONTENTS Executive Summary ................................................................................................................. iii 1. Introduction .......................................................................................................................... 1 2. Background .......................................................................................................................... 1 2.1. Project Description......................................................................................................... 1 2.2. Subterranean Fauna ..................................................................................................... 1 2.2.1. Stygofauna ............................................................................................................... 4 2.3. Conservation Framework.............................................................................................. 4 3. Desktop Review ................................................................................................................... 5 3.1. Stygofauna Records ...................................................................................................... 5 3.2. Habitat Assessment........................................................................................................ 5 3.2.1. Cory Borefield ........................................................................................................... 5 3.2.2. Northern Borefield .................................................................................................... 7 4. Field Survey ........................................................................................................................... 8 4.1. Sampling Effort................................................................................................................ 8 4.2. Methods .......................................................................................................................... 8 4.2.1. Field Methods ........................................................................................................... 8 4.2.2. Laboratory Methods .............................................................................................. 10 4.3. Personnel ....................................................................................................................... 10 5. Results .................................................................................................................................. 10 5.1. Sampling Efficiency ..................................................................................................... 10 5.2. Species Distributions..................................................................................................... 13 5.3. Stygofauna Values....................................................................................................... 16 6. Potential Impacts on Stygofauna.................................................................................... 16 7. Conclusions......................................................................................................................... 19 8. References .......................................................................................................................... 20 9. Appendices ........................................................................................................................ 22 Appendix 1. Stygofauna species previously recorded in the vicinity of the Project identified through desktop review. ..................................................................................... 22 Appendix 2. Details of holes sampled for stygofauna around Lake Disappointment between 2016 and 2017. ...................................................................................................... 24 Appendix 3. Stygofauna species recorded at Lake Disappointment from October 2016 to March 2017, including collection locations of each species. ........................... 25 LIST OF FIGURES Figure 1. Location of the Project............................................................................................ 2 Figure 2. Geology (Gunanya 1:100,000 map sheet) and proposed borefield locations. ................................................................................................................................... 3 Figure 3. Conceptual hydrological model of the Cory Borefield (from Strategic Water Management 2018). .................................................................................................... 6 Figure 4. Conceptual hydrological model of the Northern Borefield (from Strategic Water Management 2018). .................................................................................................... 7 Figure 5. Locations of sites sampled for stygofauna in and around Lake Disappointment from