South West Waterways

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
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 - Victorias
  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

27
Scales - Spatial Temporal

• Environmental data
• variable
• in space and time
• Analysis needs to consider this
• Must consider cumulative effects
• the accumulation of effects resulting from a
  number of individual actions on the environment,
  distributed through space and/or time
• many types (not necessarily linear)
• recovery, threshold, multiplicative, etc.

28
Condition Assessment - Mitchell

• 10 factors important to aquatic organisms
• bed composition, pools riffles
• bank verge vegetation
• cover for fish (snags, boulders, undercut banks)
• flow depth velocity
• submerged vegetation, instream organic matter
• sedimentation or erosion
• Environmental rating
• very poor - poor - moderate - good - excellent

29

• Excellent
• Generally in forested areas
• Otways (e.g. Gellibrand, Barham, Ford Rivers)
• Moorabool River (below Lal Lal Reservoir)
• Very Poor
• Generally in/near urban areas, or where intensive
  agriculture
• Naringhil Kuruc-a-Ruc Cks
• Yarrowee River, Winter Ck (near Ballarat),

e.g.
e.g.