Environmental Water Requirements for The Rubicon River Tom Krasnicki Aquatic Ecologist Water Assessment and Planning Branch Water Resources Division DPIWE. Report Series WRA 02/01 May, 2002. Table of Contents ACKNOWLEDGEMENTS i GLOSSARY OF TERMS ii EXECUTIVE SUMMARY 1 1. INTRODUCTION 3 2. THE RUBICON RIVER 3 2.1 General Description 4 2.1.1 Catchment and Drainage System 3 2.1.2 Geomorphology and Geology 6 2.1.3 Climate and Rainfall 7 2.1.4 Vegetation 8 2.1.5 Land Use and Degradation 9 2.1.6 Port Sorell Estuary 9 2.1.7 Hydrology 11 2.2. Site Selection 13 2.2.1 The Rubicon River at Smith and Others Rd. 13 3. VALUES 15 3.1 Community Values 15 3.2 State Technical Values 17 3.3 Endangered species 18 3.4 Values Assessed 19 4. METHODOLOGY 20 4.1 Physical Habitat Data 20 4.2 Biological Data 21 4.2.1 Invertebrates 21 4.2.2 Fish 21 4.3 Hydraulic Simulation 21 4.4 Risk Analysis 22 5. RESULTS 24 5.1 Physical Habitat Data 24 5.2 Biological Data 25 5.3 Risk Analysis 26 6. DISCUSSION 29 6.1 Vertebrate Fauna 30 6.1.1 Mordacia mordax and Geotria australis 30 6.1.2 Gadopsis marmoratus 30 6.1.3 Pseudaphritis urvillii 31 6.1.4 Galaxias truttaceus and Galaxias maculatus 31 6.1.5 Galaxias brevipinnis and Neochanna cleaveri 31 6.1.6 Prototroctes maraena 32 6.1.7 Lovettia sealii and Retropinna tasmanica 32 6.1.8 Anguilla australis 32 6.1.9 Salmo trutta 32 6.1.10 Nannoperca australis and Perca fluviatilis 33 6.2 Invertebrate Fauna 33 6.2.1 Astacopsis gouldi 33 6.3 Flow Recommendations 34 6.3.1 Rubicon River at Smith and Others Rd. 35 7. REFERENCES 36 APPENDIX 1. WUA GRAPHS FOR THE RUBICON RIVER 40 Front cover: Rubicon River Photo: Mic Clayton 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 author 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 Rubicon River catchment and the assistance of Jo Bentley of the Greater Rubicon Catchment Management Group. Copyright Notice: Material contained in the report provided is subject to Australian copyright law. Other than in accordance with the Copyright Act 1968 of the Commonwealth Parliament, no part of this report may, in any form or by any means, be reproduced, transmitted or used. This report cannot be redistributed for any commercial purpose whatsoever, or distributed to a third party for such purpose, without prior written permission being sought from the Department of Primary Industries, Water and Environment, on behalf of the Crown in Right of the State of Tasmania. Disclaimer: Whilst DPIWE has made every attempt to ensure the accuracy and reliability of the information and data provided, it is the responsibility of the data user to make their own decisions about the accuracy, currency, reliability and correctness of information provided. 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. (2002). Environmental Water Requirements for the Rubicon River . Department of Primary Industries, Water and Environment, Hobart Technical Report No. WRA 02/01 ISSN: 1448-1626 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 Act 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 minimum flow requirements for the Rubicon River. Both community values 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 common jollytail ( Galaxias maculatus ), blackfish ( Gadopsis marmoratus ) and short finned eel ( Anguilla australis ) populations; • Maintain in-stream habitat for macroinvertebrate populations. Recreational values targeted were: • Maintain fish stocks of brown trout ( Salmo trutta ). • Maintain rearing and/or spawning habitat for brown trout. 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 flows at which certain percentages of habitat loss occurred for individual species, relative to the habitat available at a pre-determined reference condition. 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: . • Protect whitebait and native fish populations. • Maintain suitable flows for the protection of the Australian grayling ( Prototroctes maraena ) and the giant freshwater crayfish ( Astacopsis gouldi) , • Maintain fish stocks, including Australian grayling ( Prototroctes maraena ), freshwater flathead ( Pseudaphritis urvillii ), spotted galaxias ( Galaxias truttaceus ), climbing galaxias (Galaxias brevipinnis ), common jollytail ( Galaxias maculatus ), Tasmanian mudfish (Neochanna cleaveri ) Tasmanian whitebait ( Lovettia sealii ), Smelt ( Retropinna tasmanica ), river