Upper Murrumbidgee River in the Murrumbidgee I and II Water Sources 2023

Background

The Snowy Water Initiative was formally established in 2002 to achieve significant improvements in river health by releasing environmental water into the Snowy, upper Murrumbidgee, and upper Murray River systems. Significant investments from New South Wales, Victorian and Commonwealth governments have been made to recover water for the environment in these systems.
In determining how to use the water, the partner governments jointly agreed that ecological objectives would be achieved by storing and then releasing sufficient volumes to provide higher flows.

Throughout the 2023-24 water year, the department's Environment and Heritage Group will be delivering environmental water from Tantangara Dam into the upper Murrumbidgee River that flows through the Murrumbidgee I and II Water Sources. The water sources are described in the Water Sharing Plan for the Murrumbidgee Regulated River Water Source 2016.

During the restriction period, releases will peak at 1,500 megalitres per day on 20 September, representing the last of three high-flow releases the year. The high flow release forms part of the Snowy and Montane River Increased Flows (SMRIF) strategy that will deliver environmental water from Tantangara Dam into the upper Murrumbidgee River in 2023.

The releases are designed to mimic the natural characteristics of the Murrumbidgee River, including snowmelt and ‘freshes’ that occurred before the construction of the Snowy Mountains Scheme. The high flows improve the physical condition of in-stream habitat by scouring and transporting fine sediment (i.e. primarily, sand, silt and clay). Meeting ecological objectives was identified as a high priority during the Snowy Water Inquiry.

A temporary water restriction, under section 324 of the Water Management Act 2000, will be imposed to protect the environmental flows from extraction by unregulated licence holders, since no protection for environmental flow exists in the relevant water sharing plan. The order effectively increases the access threshold of the unregulated river access licences by the modelled volume of environmental flow passing the two reference gauges for the Murrumbidgee I and II water sources. Any water in the river above the increased thresholds will still be available to unregulated licence holders.

The section 324 order will not impact access for domestic and stock licence holders, so they can continue to extract water during the restrictions.

How to comply with the temporary water restriction

If you are an unregulated access licence holder in either the Murrumbidgee I or II water source, you can only pump during the 1 September – 30 November period if flows at your flow reference gauge are above the temporarily increased commence-to-pump thresholds for that day, as published in Table 1 of the access announcement on the WaterInsights page for the Murrumbidgee II at: waterinsights.waternsw.com.au/16481-murrumbidgee-ii/updates

For further instructions on how to comply, follow the “how-to guide” on WaterNSW’s WaterInsights page for the Murrumbidgee II.

Reasons for decision

Section 324 of the Water Management Act 2000 allows the Minister or delegate to order that temporary water restrictions within a water source(s) are to have effect for a specified period, if these restrictions are determined to be in the public interest.

Examples of the public interest referred to in section 324(1) are “to cope with a water shortage, threat to public health or safety or to manage water for environmental purposes”.

It is in the public interest to make an order to restrict access of the environmental flow in the upper Murrumbidgee River in the Murrumbidgee I and II Water Sources to manage water for environmental purposes, for the following reasons:

• recovered environmental water is only available due to public investments made for the purpose of improving river health
• the environmental releases are designed to promote river functions in the bed of the upper Murrumbidgee River, wet the riparian zone and promote the establishment of aquatic and riparian vegetation and provide important habitat for water dependant reptiles and animals including native fish, water bugs, frogs and platypus
• the high-flow release in mid-September provides daily and seasonal flow variability which assists the river to re-establish stream function, particularly flushing fine sediment and improving in-stream habitat
• the results from previous studies show that Snowy montane rivers respond well to these seasonal high-flow events
• the release design has received input and support from the Snowy Advisory Committee and ecological experts
• the flows protected under this restriction are part of planned series of flow events, with each event intended to generate individual environmental outcomes. The series of events combine to generate a more lasting, cumulative ecological benefit for the upper Murrumbidgee River
• if the environmental release took place without a restriction, unregulated river access licences holder could lawfully extract the resulting environmental flows, limiting the environment outcomes described above and working against the public interest

Accordingly, the section 324 order is being made to protect the delivery of environmental water in the upper Murrumbidgee River. The section 324 order also includes the ability to lift orders, via responsive management if the environmental releases need to be cancelled, e.g., if rainfall caused increased flows and the environmental releases would exacerbate flooding risks.

Allan Raine
Director Water Planning Implementation
Department of Planning and Environment – Water

23 August 2023