South West Waterways Values, Condition & Impacts A context for water issues in the West RFA

1. South West Waterways Values, Condition & Impacts A context for water issues in the West RFA Dr. Tim Fletcher

2. Introduction • General presentation - sets the context for more specific presentations which follow • The information presented is not “new” • it is a broad summary of the state of knowledge of regional waterways • Presents the big picture of waterways in the region - both the condition & impacts • puts RFA water issues in regional context

3. Outline • Waterways in the West RFA region • Values & uses (demands) of waterways • Impacts on waterways • Condition of regional waterways • Methods to protect waterway values

4. Waterways within the West RFA Covers part of 16 river basins Goulburn Campaspe Loddon Avoca Yarra Maribyrnong Werribee Wimmera-Avon Moorabool Barwon Otway Coast Lake Corangamite Hopkins Portland Coast Glenelg Millicent

5. Waterways in the Corangamite region(Barwon, Moorabool, Lake Corangamite & Otway Coast Basins)

6. Waterway Values & Uses • Environmental • Economic • Social Many competing demands...

7. Economic & Social Values • Water supply • drinking & domestic (e.g. garden watering), industrial, agriculture (stock & irrigation) • Extraction • fish, gravel, sand, soil (floodplain) • Tourism & recreation • walking, sightseeing, fishing, boating, swimming • Aesthetics • rural landscape, parkland, urban design • Waste discharge • sewerage, industry, stormwater

8. Environmental Values • Instream • habitat for fish, macroinvertebrates (“bugs”), macrophytes (“plants”) • Riparian (streamside) zone • habitat corridor, unique landscape element (ecotone) • Floodplain • intermittent habitat (billabongs), nutrient transfer, sediment deposition • Dynamic, variability, diversity

9. Impacts on Waterways • Urbanisation • Agriculture • Forestry • Others (e.g. mining)

10. Impacts of Urbanisation (e.g Geelong, Ballarat) • Hydrology • increased impervious area, decreased vegetation cover • “flashy catchments” - rapid flows over short time • leads to downstream erosion & scouring • river isolated from its floodplain • extraction of flows for water supply • Water quality • increased sediment transport • increased nutrients (N, P) - sewerage, fertilisers, etc • reduced dissolved oxygen (DO) • pathogens, heavy metals, hydrocarbons, litter • Channel & riparian zone • gross modification • channelisation, clearing of vegetation - loss of diversity • barriers to fish passage (weirs, culverts, etc)

11. Impacts of Agriculture • Hydrology • Vegetation removal (runoff, erosion,  groundwater, salinity) • Diversion & storage of stream water • impacts on aquatic communities (flora & fauna) • Flood control (levees, etc) • river isolated from floodplain, flow concentration, erosion • Water Quality • sediment & nutrients (fertiliser use, stock access & cropping, soil erosion) • pathogens (stock access) • potential chemical contamination (herbicide/pesticide) • changed organic inputs, dissolved oxygen levels

12. Impacts of Agriculture (cont.) • Channel & Riparian Zone • vegetation removal (changed shade, temperature, etc) • de-snagging, channel “cleaning” & “straightening” • loss of habitat • channel deepening & erosion (from increased runoff) • fish barriers (storages, weirs, poorly designed crossings) • reduced physical and biological diversity • smaller range of habitats (suits less species)

13. Impacts of Forestry • Hydrology • short and long-term changes to water yield • presentation by Dr. Rob Vertessy • Water quality • sediment mobilisation & transport • presentation by Dr. Jacky Croke • Channel & riparian zone • short or long-term changes to vegetation structure • depending on proximity of harvesting • generally less than urbanisation or agriculture

14. Condition of Waterways in SW Vic • Two comprehensive assessments of environmental condition: • Mitchell (1990) • 96 sites • Index of Stream Condition (ISC) (1999) • 217 sites

15. Condition Assessment - ISC • Hydrology • deviation from natural flows • Physical form • bed & bank stability • barriers to fish passage • instream habitat (snags, etc) • Streamside zone • vegetation cover & condition, weeds, regeneration • Water quality • total phosphorus, turbidity, EC, pH • Aquatic life • macroinvertebrate population diversity  Five sub-indices  Index of Stream Condition

16. Very Poor Excellent 7% 13% Poor Good 29% 25% Moderate 26% Results • Excellent • Generally in forested areas: • Otways (e.g. Gellibrand, Barham, Ford Rivers) • Moorabool River (e.g. below Lal Lal Reservoir) • Very Poor • Generally in/near urban areas, or where intensive agriculture is present: • Naringhil & Kuruc-a-Ruc Cks • Yarrowee River & Winter Ck (near Ballarat) Mitchell, 1990

17. Results(Mitchell 1990)

18. Mundy Gully, Lismore

19. Winter Creek

20. Yarrowee River

21. Moorabool River

22. GellibrandRiver Ford River

23. Aire River Moorabool River

24. How can we best protect our waterways? • Considering that • there are many different values/uses of land and water ….

25. Protecting waterway values... • Initial assessment of capability/impacts of the particular use • Best practice land use • urbanisation • agriculture • forestry BUT all of the above depend on • Long-term environmental monitoring • both broad scale/background & specific

26. Some references Mitchell (1990). The environmental condition of Victorian streams Ladson & White (1999). An index of stream condition: reference manual Commissioner for the Environment (1988). State of the environment report 1988 - Victoria’s inland waters Corangamite CaLP (1997). Corangamite Regional Catchment Strategy Fletcher & Bren (1999). Cumulative effects analysis; grasping the big picture of environmental change in rivers. In Proceedings of 2nd Australian Stream Management Conference