Upper Murrumbidgee River in the Murrumbidgee I and II Water Sources

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.

In February and April 2023, the Department of Planning and Environment – Environment and Heritage Group (DPE-EHG) 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.

The environmental water will be delivered via three releases from Tantangara Dam, starting 7 February, 26 February and 22 April 2023. The three events combined will release a total of 880 megalitres (ML), with each release having a maximum release rate of 125 ML/day. The releases form 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. This summer release reflects the natural timing of events in the river and will improve the physical condition of in-stream habitat by scouring and transporting fine sediment (i.e. primarily, sand, silt and clay).

A temporary water restriction 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 Temporary Water Restriction 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

A temporary water restriction will be used to protect the upcoming environmental releases. To comply with the restriction, unregulated licence holders in the Murrumbidgee I and II must not pump if flows at the relevant gauge are below the temporarily raised access thresholds published in the order for that day.

Details on the raised access thresholds and the days they apply can be found on page 4 and 5 in the Temporary Water Restriction (Murrumbidgee I Water Source and Murrumbidgee II Water Source) Order 2023

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:

• the flow pattern provides daily and seasonal flow variability which assists the river to re-establish stream function, including flushing fine sediment and improving in-stream habitat
• the releases promote river functions in the remnant bed of the upper Murrumbidgee River, promote the establishment of aquatic and riparian vegetation and provide important habitat for water-dependant reptiles and animals including native fish, waterbugs, frogs and platypus
• results from previous studies demonstrate that Snowy montane rivers respond well to these seasonal events
• the release regime was informed by the Snowy Advisory Committee and ecological experts, and has their support
• significant investments from NSW, Victorian and Commonwealth governments have been made to achieve the environmental outcomes in the Upper Murrumbidgee River
• if the environmental release took place without the restriction, holders of regulated river access licences could lawfully extract the environmental flows, limiting the environmental outcomes described above, which would not be in 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. This means that the access to water will be reinstated if the event is cancelled due to flood risk.

Acting Director Water Planning Implementation
26 January 2023