State of the Environment Report EXECUTIVE SUMMARY There is a growing focus in the community on restoration of urban and other areas damaged by human actions. We want to clean up the environment close to where we live - our air, our open spaces, and our water. This study examines the potential for restoration of one such damaged system - the waterways of the Merri Catchment, in Melbourne’s northern suburbs. The Merri Creek rises in the foothills of the Great Dividing Range near Wallan, approximately sixty kilometres north of Melbourne, and flows south, through rural, industrial and residential areas to its confluence with the Yarra River near Dights Falls in the inner city suburb of Abbotsford. The Merri Creek itself is approximately 80 kilometres long and the catchment drains an area of approximately 400 square kilometres. This study presents all the available information on the state of the waterways of the Merri Catchment. It identifies, as far as possible, the problems resulting from human activities. Throughout the study the principles of Integrated Catchment Management have been used, in particular the concepts of: • recognition of the intrinsic worth of the natural environment • an interdisciplinary approach and a systems perspective • concern to include community values • an integrated environmental and socio-economic approach The most important findings of the State of the Environment Report are that: • Agricultural practices - such as removal of riparian vegetation, drainage of wetlands and stock trampling of stream banks - are a major cause of aquatic ecosystem degradation. • Urban development has massively altered the flow and the water quality of the waterways, for example by increasing the quantity of stormwater which carries a high load of contaminants. • Sewage treatment in the catchment is inadequate, with effluent from Craigieburn Sewage Treatment Plant and from unsewered industrial and residential areas contributing significantly to the nutrient problem in some parts of the Merri Catchment. • Industrial activities still pollute the waterways - mainly from inadequate storage, disposal and transport of materials such as chemicals. • Despite these obvious problems, there are still long stretches of the Merri Creek that have National, State, Regional or Local biological significance, with surviving remnant populations of increasingly rare species such as the Growling Grass Frog, Freshwater Blackfish and Rufous Night Heron and habitats such as the endangered Western (Basalt) Plains Native Grassland. • There is strong community support for waterway restoration. i Waterways of the Merri Catchment Page ii State of the Environment Report Table of Contents 1. INTRODUCTION ...................................................................................................9 1.1 The Merri Creek and its Catchment....................................................................................................... 9 1.2 Background to the Report...................................................................................................................... 10 1.3 The Merri Creek Management Committee.......................................................................................... 12 1.4 Monash University Master of Environmental Science ........................................................................ 12 1.5 Methodology and Methods..................................................................................................................... 13 1.6 Structure of this Report ......................................................................................................................... 15 1.7 A Journey down the Merri Creek ........................................................................................................... 2 2. THE HUMAN ENVIRONMENT ............................................................................11 2.1 Introduction............................................................................................................................................... 9 2.1.1 Previous work...................................................................................................................................... 9 2.2 Changes in Human Use since Settlement.............................................................................................. 12 2.2.1 Introduction....................................................................................................................................... 12 2.2.2 Agriculture ........................................................................................................................................ 12 2.2.3 Industrialisation................................................................................................................................. 14 2.2.4 Urbanisation ...................................................................................................................................... 16 2.3 Current Community Attitudes and Uses .............................................................................................. 20 2.4 Agencies and Institutions ....................................................................................................................... 23 2.4.1 The Players........................................................................................................................................ 23 2.5 Legislation, Strategies and Policies ....................................................................................................... 29 2.5.1 The Environment Protection Act 1970 (Vic.) ................................................................................... 29 2.5.2 Other State legislation ....................................................................................................................... 34 2.5.3 Commonwealth strategies, legislation and policies........................................................................... 35 2.6 Current Arrangements .......................................................................................................................... 36 2.7 Conclusions.............................................................................................................................................. 37 3. GEOMORPHOLOGY AND FLOW ......................................................................45 3.1 Introduction............................................................................................................................................. 43 3.1.1 Previous work.................................................................................................................................... 43 3.2 “Natural” states ...................................................................................................................................... 45 3.3 Existing states.......................................................................................................................................... 45 3.3.1 The Merri Creek................................................................................................................................ 46 3.3.2 Summaries of the Significant Tributaries.......................................................................................... 50 3.3.3 Wetlands............................................................................................................................................ 54 3.3.4 Water Harvesting .............................................................................................................................. 55 iii Waterways of the Merri Catchment 3.3.5 Stormwater ........................................................................................................................................ 55 3.3.6 Floods ................................................................................................................................................ 58 3.3.7 Groundwater...................................................................................................................................... 59 3.4 Conclusions.............................................................................................................................................. 60 4. WATER QUALITY...............................................................................................67 4.1 Introduction............................................................................................................................................. 71 4.1.1 Previous Work................................................................................................................................... 71 4.1.2 Scope of this section.......................................................................................................................... 73 4.2 ‘Natural’ states........................................................................................................................................ 73 4.3 Water quality parameters as indicators of stream health................................................................... 74 4.4 Existing states.......................................................................................................................................... 74 4.4.1 Physical and chemical parameters..................................................................................................... 74 4.4.2 Biological Parameters.......................................................................................................................