Environmental Water Requirements for The Emu River Tom Krasnicki Aquatic Ecologist Water Assessment Section Water ResourcesDivision DPIWE. Report Series WRA 01/07 December, 2001. Table of Contents ACKNOWLEDGEMENTS i GLOSSARY OF TERMS ii EXECUTIVE SUMMARY 1 1. INTRODUCTION 3 2. EMU RIVER 4 2.1 General Description 4 2.1.1 Catchment and Drainage System 4 2.1.2 Geomorphology and Geology 5 2.1.3 Climate and Rainfall 5 2.1.4 Vegetation 5 2.1.5 Land Use and Degradation 6 2.1.6 Emu Estuary 6 2.1.7 Hydrology 7 2.2. Site Selection 9 2.2.1 The Emu River off Manina Rd 9 3. VALUES 11 3.1 Community Values 11 3.2 State Technical Values 12 3.3 Endangered species 13 3.4 Values Assessed 15 4. METHODOLOGY 16 4.1 Physical Habitat Data 17 4.2 Biological Data 17 4.2.1 Invertebrates 16 4.2.2 Fish 18 4.2.3 Platypus 17 4.3 Hydraulic Simulation 18 4.4 Risk Analysis 19 5 RESULTS 20 5.1 Physical Habitat Data 21 5.2 Biological Data 21 5.3 Risk Analysis 22 6 DISCUSSION 23 6.1 Vertebrate Fauna 24 6.1.1 Mordacia mordax and Geotria australis 24 6.1.2 Gadopsis marmoratus 25 6.1.3 Pseudaphritis urvillii 25 6.1.4 Galaxias truttaceus and Galaxias maculatus 25 6.1.5 Galaxias brevipinnis and Galaxias cleaveri 26 6.1.6 Prototroctes maraena 26 6.1.7 Lovettia sealii and Retropinna tasmanica 26 6.1.8 Anguilla australis 26 6.1.9 Salmo trutta and Oncorhyncus mykiss 27 6.1.10 Ornithorhyncus anatinus 27 6.2 Invertebrate Fauna 28 6.2.1 Astacopsis gouldi 28 6.2.2 Beddomeia protuberata 28 6.3 Flow Recommendations 29 6.3.1 Emu River off Manina Rd 29 7 REFERENCES 30 APPENDIX 1. WUA GRAPHS FOR THE EMU RIVER 34 Front cover: Emu River at Upper Natone Rd Photo: Tom Krasnicki Acknowledgments This study has been conducted under the Natural Heritage Trust as part of the project "Tasmanian Environmental Flows" (NRC13182) and has received funding from the Commonwealth Government and the Department of Primary Industries, Water and Environment. The authors would like to thank the following individuals from the DPIWE for their assistance in field data collection and for assistance in preparation of this report: Cameron Amos, John Gooderham, Adam Jagla, David Horner, Mark Nelson, Rebecca Pinto, Nick Probert, Martin Read, Bryce Graham and Ian Tye. The author would also like to acknowledge the support received from landowners and stakeholders within the Emu River catchment. Special thanks to Tony Clifford from Gunns Pty Ltd. for providing information on the operation of the Burnie Mill Water Supply System. 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The Department of Primary Industries, Water and Environment, its employees and agents, and the Crown in the Right of the State of Tasmania do not accept any liability for any damage caused by, or economic loss arising from, reliance on this information. Preferred Citation Krasnicki, T. J.. (2001). Environmental Water Requirements for the Emu River. Department of Primary Industries, Water and Environment, Hobart Technical Report No. WRA 07/2001 ISBN: The Department of Primary Industries, Water and Environment The Department of Primary Industries, Water and Environment provides leadership in the sustainable management and development of Tasmania’s resources. The Mission of the Department is to advance Tasmania’s prosperity through the sustainable development of our natural resources and the conservation of our natural and cultural heritage for the future. The Water Resources Division provides a focus for water management and water development in Tasmania through a diverse range of functions including the design of policy and regulatory frameworks to ensure sustainable use of the surface water and groundwater resources; monitoring, assessment and reporting on the condition of the State’s freshwater resources; facilitation of infrastructure development projects to ensure the efficient and sustainable supply of water; and implementation of the Water Management Act 1999, related legislation and the State Water Development Plan. i Glossary of Terms ARMCANZ Agriculture and Resource Management Council of Australia and New Zealand ANZECC Australian and New Zealand Environment and Conservation Council cumec a measure of flow discharge. 1 cubic meter per second; equivalent to 86.4 ML/day Commissional Water Under the Water Act 1957, the right to take water from a water resource Right (C.W.R.) (watercourse, lake, river, stream or any surface water or groundwater) for commercial (irrigation) use. discharge a volume of water passing a given point in unit time Water Provisions for Are that part of the Environmental Water Requirements that can be met. That is, the the Environment water regime for the environment through agreement or negotiation. (WPEs) Environmental Water Are descriptions of the water regimes needed to sustain ecological values of aquatic Requirements ecosystems at a low level of risk. These descriptions are developed through the (EWRs) application of scientific methods and techniques or through the application of local knowledge based on many years of observations. IFIM Instream Flow Incremental Methodology macrophytes large aquatic plant macroinvertebrates invertebrate (without a backbone) animals which can be seen with the naked eye. megalitre a measure of water equivalent to 1000 000 litres (or about the size of an Olympic swimming pool) pools deep, still water , usually within the main river channel riffles areas of fast moving, broken water Riparian Right Under the Water Management Act 1999 a person who owns land or occupies a property may take water from a watercourse or lake on, or adjoining, that land for the purposes of domestic use, or irrigation of a household garden, or stock watering, or firefighting, or drilling. riparian vegetation vegetation on the banks of streams and rivers run unbroken, moving water sinuosity degree of “bendiness” of a river (ratio of valley length: river length) snags instream woody debris substrate the structural elements of the river bed; boulder, cobble etc. taxon (plural: taxa) the member of any particular taxonomic group eg. a particular species, family etc. transect in this study, a line across the river bed perpendicular to flow, used for a standardised collection of depth, velocity and substrate information WL Water licence – Under the Water Management Bill 1999 water licences are issued for the purpose of taking water from a water resource (watercourse, lake, river, stream or any surface water or groundwater). The amount of water taken depends upon the water allocation under the issued licence. The Department of Primary Industry, Water and the Environment allocates water for irrigation, stock and domestic, aesthetic, commercial and industrial purposes. WUA Weighted Useable Area, or the amount of useable habitat available in the river for a species ii Executive Summary This report details the ecological assessment of flow requirements for the Emu River. Both community and State technical values were identified as part of the assessment process and the ecological values identified from this process were used to focus the assessment of Environmental Water Requirements. Ecological values specifically targeted included: • Maintain habitat for, brown trout (Salmo trutta), river blackfish (Gadopsis marmoratus) common jollytail (Galaxias maculatus) and shortfinned eel (Anguilla australis) populations; • Maintain platypus (Ornithorhynchus anatinus) habitat and • Maintain habitat for macroinvertebrate populations found in the Emu River. A risk analysis was performed to provide (1) a series of options for negotiation of Water Provisions for the Environment and (2) the ecological risk of failure in not achieving these flows for each of these values. This was achieved by determining the flow at which the useable habitat available to a species changes by a certain percentage, relative to a reference flow. The percentage changes in habitat that determined risk categories were taken from Davies and Humphries (1996). This analysis was done for each of the key biota (including both fish and invertebrate species). Other values identified, and discussed elsewhere in the report include: • Maintain suitable flows for the protection of the Australian grayling (Prototroctes maraena), the giant freshwater crayfish (Astacopsis gouldi), and the freshwater snail (Beddomeia protuberata). • Maintain fish stocks, including Australian grayling, freshwater flathead (Pseudaphritis urvillii), spotted galaxiid (Galaxias truttaceus), common jollytail (Galaxias maculatus), Tasmanian whitebait (Lovettia sealii), river blackfish, brown trout and shortfinned eel (Anguilla australis). • Maintain rearing and/or spawning habitat for lampreys (Mordacia mordax and Geotria australis), river blackfish, brown trout (Salmo trutta), freshwater flathead, spotted galaxiid and common jollytail. • Maintain instream woody debris as habitat for river blackfish and trout. One site was selected to represent the river, identified by preliminary analysis of river reach characteristics along the river continuum. The Environmental Water Requirements and associated risk of failure to provide these flows are as follows. Emu River – Off Manina Rd The EWRs relate to the Emu River reach extending upstream from Fern Glade Reserve to a point approximately 500m above the confluence with the Pet River. The flow recommendations resulting from the risk analysis are considerably influenced by the water requirements for macroinvertebrate species found in the Emu River.