Government of Western Australia Department of Water River health assessment in the lower catchment of the Blackwood River Assessments in the Chapman and Upper Chapman brooks, the McLeod, Rushy and Fisher creeks and the lower Blackwood River using the South West Index of River Condition Securing Western Australia’s water future Report no. WST 68 February 2015 River health assessment in the lower catchment of the Blackwood River Assessments in the Chapman and Upper Chapman Brooks, the McLeod, Rushy and Fisher Creeks and the lower Blackwood River using the South West Index of River Condition Securing Western Australia’s water future Department of Water Water Science Technical series Report no. 68 February 2015 Department of Water 168 St Georges Terrace Perth Western Australia 6000 Telephone +61 8 6364 7600 Facsimile +61 8 6364 7601 National Relay Service 13 36 77 www.water.wa.gov.au © Government of Western Australia February 2015 This work is copyright. You may download, display, print and reproduce this material in unaltered form only (retaining this notice) for your personal, non-commercial use or use within your organisation. Apart from any use as permitted under the Copyright Act 1968, all other rights are reserved. Requests and inquiries concerning reproduction and rights should be addressed to the Department of Water. ISSN 1836-2869 (print) ISSN 1836-2877 (online) ISBN 978-1-922124-98-2 (print) ISBN 978-1-922124-99-9 (online) Report to the South West Catchments Council This is a joint initiative of the Department of Water and the South West Catchments Council through funding from the Australian Government’s Caring for our Country and the Government of Western Australia. Acknowledgements The Department of Water would like to thank the following for their contribution to this publication: staff from the South West Catchments Council (SWCC) for assistance with site selection and landholder liaison; staff from the Department of Water (DoW), SWCC and Lower Blackwood Land Conservation District Committee (LCDC) for assistance with fieldwork; Kelli O’Neill, Emma van Looij and Lynette Galvin (DoW) for analysis of macroinvertebrate data; Dominic Heald (DoW) for analysis of water quality data; Lidia Boniecka and Lauren Greening (DoW) for assistance with rainfall and surface water analysis; Deepak Shakya for defining catchment boundaries and modelling mean annual flow; Jo Hugues-Dit-Ciles, Lorraine Duffy (SWCC), Kim Williams (DPaW) and Krish Seewraj (DoW) for reviewing this report. For more information about this report, contact Gillian White, Water Science Branch, Department of Water Citation White, G, Storer, T & Kitsios, A 2015, River health assessment in the lower catchment of the Blackwood River, Assessments in the Chapman and Upper Chapman brooks, the McLeod, Rushy and Fisher creeks and the lower Blackwood River using the South West Index of River Condition, Water Science Technical Series, report no. 68, Department of Water, Perth. Cover photograph: lower reach of McLeod Creek, February 2013 (T. Storer) Disclaimer This document has been published by the Department of Water. Any representation, statement, opinion or advice expressed or implied in this publication is made in good faith and on the basis that the Department of Water and its employees are not liable for any damage or loss whatsoever which may occur as a result of action taken or not taken, as the case may be in respect of any representation, statement, opinion or advice referred to herein. Professional advice should be obtained before applying the information contained in this document to particular circumstances. This publication is available at our website <www.water.wa.gov.au> or for those with special needs it can be made available in alternative formats such as audio, large print, or Braille. Water Science Technical Series, report no. 68 Contents Summary ..............................................................................................................................xiii 1 Introduction ........................................................................................................................ 1 1.1 Study objectives .................................................................................................................. 1 2 Study area ......................................................................................................................... 2 2.1 Location .............................................................................................................................. 2 2.2 Elevation ............................................................................................................................. 5 2.3 Geology, hydrogeology and soils ....................................................................................... 6 2.4 Climate .............................................................................................................................. 10 2.5 Surface water .................................................................................................................... 14 2.6 Land use ........................................................................................................................... 18 2.7 Ecological value ................................................................................................................ 20 2.8 Further information ........................................................................................................... 23 3 Methods ........................................................................................................................... 24 3.1 Overview of South West Index of River Condition ........................................................... 24 3.2 Site selection, reach and catchment definition ................................................................. 26 3.3 Indicator selection and data collection schedule .............................................................. 29 3.4 Data collection and analysis methods .............................................................................. 32 3.4.1 Theme: catchment disturbance ............................................................................................. 33 3.4.2 Theme: hydrological change ................................................................................................. 37 3.4.3 Theme: fringing zone ............................................................................................................ 41 3.4.4 Theme: physical form ........................................................................................................... 43 3.4.5 Theme: water and sediment quality ...................................................................................... 49 3.4.6 Theme: aquatic biota ............................................................................................................ 63 3.4.7 Contextual observations ....................................................................................................... 71 4 Results and SWIRC scores.............................................................................................. 72 4.1 Theme: catchment disturbance ........................................................................................ 72 4.1.1 Sub-theme: land use ............................................................................................................. 72 4.1.2 Sub-theme: infrastructure ..................................................................................................... 72 4.1.3 Sub-theme: land cover change ............................................................................................. 73 4.1.4 Scores: catchment disturbance index ................................................................................... 73 4.2 Theme: hydrological change ............................................................................................ 74 4.2.1 Sub-theme: flow stress ranking ............................................................................................. 74 4.2.2 Sub-theme: farm dams ......................................................................................................... 75 4.2.3 Scores: hydrological change index ....................................................................................... 76 4.2.4 Supplemental information ..................................................................................................... 76 Department of Water v River health assessment in the lower catchment of the Blackwood River 4.3 Theme: fringing zone ........................................................................................................ 80 4.3.1 Sub-theme: extent of fringing zone ....................................................................................... 80 4.3.2 Sub-theme: nativeness ......................................................................................................... 80 4.3.3 Scores: fringing zone index................................................................................................... 81 4.4 Theme: physical form ....................................................................................................... 84 4.4.1 Sub-theme: erosion .............................................................................................................. 84 4.4.2 Sub-theme: longitudinal connectivity .................................................................................... 86 4.4.3 Sub-theme: artificial