Environmental issues

Water

Murrumbidgee Valley environmental watering updates

Murrumbidgee River 2014 ‘piggyback’ flow        

The Office of Environment and Heritage (OEH) is currently working with partner water management agencies to plan for an environmental water release in the Murrumbidgee River during late winter to early spring 2014. The objective for this water flow is to reach many nationally significant mid-Murrumbidgee wetlands and other low-lying wetlands along the Yanco Creek system.

What is a ‘piggyback’ flow?

A piggyback flow takes advantage of higher river levels after a rain event. Environmental water allocations are added to, or piggybacked on, the higher river levels to efficiently use limited environmental water allocations, creating a more effective watering event that will access the targetted lagoons, anabranches and swamps. The amount of water released is calculated to hold the river below minor flood levels.

What level will the Murrumbidgee piggyback flow reach?

The environmental water release is designed to add to natural flows so that the river level approaches, but does NOT exceed 4.9 metres (or approx. 27,400 megalitres (ML) per day) at Wagga Wagga. This is well below the minor flood level of 7.3 m and 1 m lower than previous environmental water release levels in 2011.

How much water will be released?

The volume of environmental water released over the duration of the event could range from 40,000 ML to a maximum of 200,000 ML, depending on allocation availability and the size of the base flow. The peak of the flow event would be expected to last for about four days.

Why is it being planned?

During the drought years of 2002-2010, hundreds of natural wetlands which connect to the Murrumbidgee River during rising river flows remained dry. The lack of flows to these wetlands has resulted in severe impacts on their vegetation and biology. The planned environmental water releases will be designed to inundate a large number of the lower lying wetlands and greatly assist in their recovery.

When will it happen?

The Murrumbidgee piggyback flow is being planned to occur sometime during the period July-September 2014. The actual commencement date and duration for the event will depend on rainfall. The potential timing, based on Bureau of Meteorology rainfall forecasts and State Water operational limitations, is as follows:

  • July - unlikely due to operational constraints
  • August - most likely due to forecast favourable conditions
  • September - less likely: forecast is below-average catchment rainfall, other competing watering actions will commence.

Will it impact me?

If you have property that is normally affected by rising Murrumbidgee River levels, there is a possibility that you could be affected. However, as the proposed release is well below the minor flood level, nuisance or impacts are expected to be minimal and within the normal expected range of river water levels.

Who is responsible for the event?

OEH manages environmental water allocations in NSW and is the lead agency for the environmental flow event. State Water manages water orders and deliveries.

Partnering agencies include State Water, NSW Office of Water, Riverina Local Lands Services and the Commonwealth Environmental Water Office. 

How will I know if the flow is occurring?

Stakeholders will be notified prior to release of environmental water, once a commencement window has been confirmed. If you wish to be notified, ensure OEH has your appropriate contact details by emailing us at the address below. 

If OEH does not proceed with a piggyback flow, or it is commenced and abandoned, stakeholders on our contact lists will also be directly notified.

Where do I get more information?

Updates will be regularly posted to this website. If you have a specific query or wish to be included on our notifications list, please contact:

James Maguire
OEH Senior Environmental Water Management Officer - Murrumbidgee
Email james.maguire@environment.nsw.gov.au
Environment Line: 131 555 quoting 'Murrumbidgee Environmental Flow' 

Page last updated: 24 July 2014