Environmental watering – How is it the same or different from floods? Denis Flett Chairperson, Victorian Environmental Water Holder Friday 14 November 2014

Overview What is environmental watering? Floods are important for the environment Risk management is key So how do we manage environmental water? Manage risk while optimising environmental outcomes

A short (crude!) history Dams were constructed Increased water use Decreased river health Government invested in recovering water for the environment > environmental watering

History of Government commitment to water for the environment 1997 Murray-Darling Basin Cap on diversions introduced 2003 The Living Murray program introduced (to recover 500GL for the River Murray) – the start of government investment in water recovery 2005 Victorian Environmental Water Reserve and regional sustainable water strategies introduced 2007 Commonwealth Environmental Water Holder established 2011 Victorian Environmental Water Holder established on 1 July 2011

Releasing environmental water from reservoirs to improve the health of waterways The aim is to help plants and creatures survive, feed, breed and flourish Environmental water releases mimic some of the flows that would have occurred naturally before major reservoirs were built What is environmental watering? “ Putting back some of the flow regime ”

Why healthy waterways matter

Floods are important for ecological health Movement of carbon and nutrients (boom for fish and bugs) Stabilisation of riverbanks (through better vegetation) Increase in water quality (regular flooding avoids leaf litter build up) Flush out salt (rehabilitation of salty wetlands) ….all of which support native plant and animal species Floods and the environment

BUT: Environmental assets share the floodplain with economic and social assets… Floods and the environment Managed environmental water is mostly restricted to in-channel flows. Floodplain watering is only considered if risks can be managed and consent is provided by land owners / managers. SO:

Case study 1: Goulburn River (Dec 2013) Delivery of flows within the river channel, below flood levels that will pose a risk to private land Case study 2: Barmah Forest ( ) With permission, active delivery to the floodplain Two examples of environmental watering Both of these examples demonstrate risk management with key partners

In-channel Vs overbank flows (Case study 1: Goulburn River)(Case study 2: Barmah Forest)

Case study 1 – Goulburn River Fresh (Dec 2013) Aim of watering: Stimulate fish breeding (golden perch) Support establishment of amphibious bank vegetation Support macro-invertebrate response Desired environmental flow rate: Up to 15,000ML / day for 2 days

Case study 1 – Goulburn River Risk management 15,000 ML/day for 2 days desired for maximum environmental outcomes Constraints considered (in partnership with storage managers) Possible private land impacts Difficulty of timing releases to supplement unregulated tributary inflows Watching the forecast: rainfall and natural flooding After consideration of constraints, environmental water managers ensured the flow peaked at only 7,461 ML / day

Case study 1 – Goulburn River Environmental outcomes Golden perch spawning was detected 2 days after the start of the rise of the fresh, as well as at the peak of the fresh (7,416 ML/day at McCoys Bridge) Re-establishment of amphibious lower bank vegetation

Case study 2 – Barmah Forest Large-scale floodplain watering (Nov 2013) Aim of watering: Growth of moira grass (incl. flowering and seed dispersal), plus other benefits for fish, birds, bugs, vegetation etc Importance of moira grass: Important for nutrient cycling and as food and habitat for animals Flooding requirements: >0.5 metres depth for >3 months, followed by summer drying

Moira grass extent reduced by 96% over 80 years Credit: Keith Ward, Goulburn Broken CMA

18,000 ML/day at Tocumwal desired for maximum environmental outcomes There was a risk of NSW private property impacts Worked with NSW agencies and landholders Agreed to a two-week trial at desired river level before dropping to 15,000 ML/day prior to harvest time Case study 2 – Barmah Forest Risk management

Natural flooding in Barmah Forest helped! Credit: Murray-Darling Basin Authority Natural flooding from late July to late September

Managed environmental water from early October to early December

Moira grass root system OUTCOMES!!!! 20 Moira grass flowers Moira grass flower, VEWH Keith Ward measuring moira grass length, VEWH

Environmental watering – How is it the same or different from floods? Floodplain management and environmental watering: Floodplain management aims to protect social and economic assets on a floodplain Environmental water management aims to protect environmental assets in a river channel and on a floodplain There are similarities: Risk management is inherent to both There are opportunities for synergies: Environmental flows can extend floods at acceptable levels (as in Barmah Forest) to achieve environmental outcomes Shared data and learnings?

22 Comments or questions