Constraints Management Strategy

33.Goulburn

In central Victoria, the Goulburn River and its associated floodplain and wetland habitats support intact river red gum forest; and numerous threatened fish, mammal and bird species. The Lower Goulburn floodplain covers some 13,000 ha alongside the river channel from Goulburn Weir to the River Murray junction and contains many important cultural heritage sites.

Potential constraints to environmental flow delivery in the Goulburn valley consist mainly of third party inundation impacts below Lake Eildon and around Shepparton; and timing issues to be able to supplement unregulated tributary inflows with storage releases.

To achieve higher managed flows downstream of Goulburn Weir, unregulated tributary flows downstream of Lake Eildon would need to be supplemented with either Lake Eildon releases and/or adjustments to Waranga Basin harvesting operations. Importantly, large releases relying solely on Lake Eildon are unlikely to be feasible. The reach between Lake Eildon and Goulburn Weir has a much lower channel capacity, and landholders and businesses near Alexandra and Molesworth start to get affected when any flows get above 10,000 ML/day. The role of unregulated tributaries is critical for the future of higher managed flows in the lower Goulburn system.

Consultation

Consultation with landholders and communities in the Goulburn valley has commenced. Three regional advisory groups have been formed to assist MDBA with capturing the key issues and impacts likely to arise from increased flows. MDBA’s regional consultation and analysis of the available technical work indicates that more frequent overbank environmental flows downstream of Goulburn Weir are feasible.

In addition to information gathered through the regional advisory groups, consultation during the public comment period captured a broad range of overbank flow issues likely to be experienced along the Goulburn River. Several people commented that the MDBA consultation process in the Goulburn region has been good and is beginning to capture local knowledge well. The priority actions listed for the Goulburn River were strongly supported. It was also recognised by a number of people that environmental flows will add to the biodiversity and value of the natural environment and may have positive economic outcomes, while having the additional potential to add to the amenity and quality of life for residents and visitors.
People also provided specific feedback on impacts or other issues that will be considered in future work on implementing the Strategy, including:

• 
  they don't want to see the Goulburn environment (e.g. bank erosion) or communities impacted solely to provide larger flows further downstream
  
• 
  40,000 ML/day at McCoys Bridge may be too risky as if a local rainfall event occurs as well, it could become a damaging flood (there may be a risk of unintended adverse consequences)
  
• 
  40,000 ML/day at McCoys Bridge is too close to triggering the statutory release formula for the Loch Garry flood protection scheme
  
• 
  increases in water levels don't have to be large to start affecting landholders in the mid-Goulburn, downstream of Lake Eildon. It should be acknowledged that Goulburn-Murray Water specifically constrains releases from Lake Eildon because of the risks of inundating private land in this reach
  
• 
  higher flows create access issues including road closures, these would occur in the Lower Goulburn floodplain at the range of flows being considered (25,000–40,000 ML/day)
  
• 
  the load on storm water drainage infrastructure during high river flows is a significant concern
  
• 
  risks to irrigation pumps
  
• 
  assessing the adequacy of the rainfall and river height gauging network to be able to trigger and manage environmental releases at a time of high river flows
  
• 
  how levee bank ownership and management will be considered
  
• 
  the backing up effects of high flows on tributaries means that it’s not just mainstem landholders that could be affected; there is the potential for new ‘breakaways’ to form if tributaries cannot freely drain.
  

Also raised, was that people:

• 
  want to see scenarios of what these high flows could look like (the sorts of river heights and rainfall conditions) and how they would be managed (i.e. not just a flow target)
  
• 
  need a better understanding of the role and unpredictability of tributaries in order to piggy-back environmental water on top of flow pulses.
  

34.Priority actions for 2014

MDBA consultation has captured a broad range of overbank flow issues likely to be experienced in the Goulburn River. The next step requires better

understanding of the issues and their scale of impact; and the identification and cost of potential mitigation options including:

• 
  continued commitment to active community involvement
  
• 
  improved understanding of the opportunities to supplement tributary flows
  
• 
  enabling environmental watering coordination between catchments
  
• 
  enhanced ability to forecast tributary inflows
  
• 
  improving the accuracy and confidence in flow inundation maps
  
• 
  identifying mitigation options for private and public assets
  
• 
  ensuring levee banks are to a standard strong enough to contain environmental flows
  
• 
  quantifying the broad range of impacts of delivering higher flows including issues and mitigation options
  
• 
  exploring opportunities to make policy changes to river operations
  
• 
  scoping out a regional flood warning and notification system.
  

Figure Goulburn River at Yambuna


Figure Schematic drawing of the Murrumbidgee