History - Border Rivers

Environmental watering in the Dumaresq and lower Macintyre systems 2018-19

Status: Completed

About the watering

Between 23 April and 15 May 2019, a total of 7,400 ML of Commonwealth environmental water was delivered to Mungindi (via the Dumaresq and lower Macintyre rivers), end of system for the Border Rivers.

The purpose of the water use was to provide a connecting flow to the Barwon-Darling, as well as improving tributary conditions to support native fish resilience, top up refuge pools and improve water quality. A sharp rise in flow was provided from Glenlyon Dam, peaking at around 600 ML/day and being maintained for ten days, followed by a gradual recession. The delivery reached Mungindi by 24 May 2019, almost a month after the initial release from Glenlyon Dam. There were significant losses due to the dry conditions on route, but the flows increased the chances of fish survival by improving water quality, habitat, food sources, and providing some opportunity to escape from isolated waterholes throughout the upper Barwon, Dumaresq and lower Macintyre river reaches.

Monitoring of the outcomes from this watering action was undertaken by the NSW Department of Primary Industries - Fisheries and QLD Department of Agriculture and Fisheries, the NSW Natural Resources Access Regulator and the Murray-Darling Basin Authority.

Environmental watering in the Dumaresq River (regulated) in 2017-18

Status: Completed

About the watering

Between 2 and 26 of October 2017, a total of 3,252 ML of Commonwealth environmental water was delivered to the Dumaresq River.

The purpose of the water use was to provide stable base flows in the Dumaresq River reach for native fish outcomes (access to habitat and food during reproduction). In particular, this action was designed to support flows needed by a range of native fish during peak periods of reproduction (i.e. Murray cod, freshwater catfish, olive perchlet), but to minimise risks of cold water pollution. Commonwealth environmental water was delivered as a stable baseflow (up to 160 ML/day) for three weeks, in conjunction with some small natural inflows.

This watering action was managed in cooperation with our state partners. Monitoring of the outcomes from this watering action is being undertaken by the NSW Department of Primary Industries - Fisheries and QLD Department of Agriculture and Fisheries. Fish results after the watering action indicated that Murray cod, freshwater catfish and olive perchlet successfully recruited in 2017-18, improving population resilience of native fish in the upper Border Rivers.

Environmental watering in the Severn River QLD (unregulated) in 2017-18

About the watering

CEW contributed to small and medium pulses in the reach of the Severn River that flows through Sundown National Park. Small flows in spring 2017 likely provided conditions highly conducive to native fish movement and potential reproduction.

For medium pulses in summer, the river rose about 1m at Farnbro. Although it did not exceed the 2m threshold, identified in the Moonie River (Marshall et al 2016) as triggering significant long range native fish movement, this pulse likely provided conditions that improved fish recruitment outcomes through increased habitat access and food availability.

Environmental watering in the (Dumaresq-Macintyre rivers Qld unregulated) in 2017-18

Status: Completed

About the watering

Commonwealth environmental water from Queensland unregulated entitlements contributed to two small flow events in 2017-18. Increased in-stream flows contributed to protecting and restoring water-dependent ecosystems by increasing flow variability.

Approximately 641 ML of Commonwealth environmental water was provided, consisting of:

• approximately 292 ML (unregulated) in the Macintyre and Dumaresq rivers (Qld) in July 2017
• approximately 349 ML (unregulated) in the Lower Macintyre River (Qld) in mid-October 2017.

Environmental watering in the Severn River (NSW) in 2017-18

Status: Completed

About the watering

Between 21 August and 16 October 2017, a total of 8,000 ML of NSW environmental water, available under the ‘stimulus flow’ provisions of the NSW water sharing plan, and 684 ML of Commonwealth environmental water was delivered to the NSW Severn River.

The purpose of the water use was to initially provide increased access to food and habitat before recruitment, followed by a stable baseflow to maintain access to core habitat throughout recruitment. In particular, this action was based on 2016-17 monitoring which suggested that Murray cod had not successfully bred since 2013, when a priming pulse was provided. NSW contribution began on 21 August 2017 and peaked at 2,079 ML/day (Pindari Dam) on 23 August. After this brief pulse, there was a long period of stable baseflows (~50ML/day) until mid-October 2017. Commonwealth environmental water was delivered on the 24 September to extend baseflows and this delivery occurred in conjunction with ‘translucency flow’ provisions of the NSW water sharing plan.

This watering action was managed in cooperation with the NSW Office of Environment and Heritage, NSW Department of Primary Industries – Fisheries, NSW Department of Industry – Water and WaterNSW. Other state partners were also informed about this watering action.

Monitoring of the outcomes from this watering action is being undertaken by the NSW Department of Primary Industries - Fisheries and QLD Department of Agriculture and Fisheries. Preliminary fish results after the watering action has indicated that Murray cod successfully recruited in 2017-18, as well as evidence of spawning aggregation of the threatened species, silver perch.

Northern Connectivity Event – regulated 2017-18

Status: Completed

About the watering

Between 4 and 20 of May 2018, a total of 4,286 ML of Commonwealth environmental water was delivered to Mungindi, end of system for the Border Rivers.

The purpose of the water use was to provide a connecting flow to the Barwon-Darling, as well as, improving tributary conditions to maintain native fish populations. An initial small peak was provided for three days, followed by a stable pulse for seven days and then a short recession. This delivery reached Mungindi on 4 May 2018, 17 days after the initial release from Glenlyon Dam. Stable flows were are between 380-430 ML/d for the majority of the watering action, providing native fish with opportunities to move and disperse throughout the upper Barwon, Dumaresq and lower Macintyre river reaches.

Monitoring of the outcomes from this watering action was undertaken by the NSW Department of Primary Industries - Fisheries and QLD Department of Agriculture and Fisheries.

Environmental watering in the Queensland Severn and lower Macintyre River systems 2016-17

Status

30 June 2017: This action is completed

About the watering

Commonwealth environmental water from Queensland unregulated entitlements contributed to a series of medium to high unregulated flow events (68,000 ML/day peak at Goondiwindi in late September) during the year. Increased in-stream flows contributed to protecting and restoring water-dependent ecosystems by increasing flow variability, end of system flows and flows to some anabranches.

Approximately 22,529 ML of Commonwealth environmental water was provided, consisting of:

• approximately 683 ML (unregulated) in the Severn River (Qld) in February 2017
• approximately 21,846 ML (unregulated) in the Macintyre and Dumaresq rivers (Qld) across flow events in July, August and October 2016 and in March 2017.

Environmental watering in the Queensland Severn and lower Macintyre River systems 2015-16

Status

30 June 2016: Completed

About the watering

Commonwealth environmental water from Queensland unsupplemented entitlements contributed to four small unregulated flow events (less than or around 10,000 ML/day at Goondiwindi) during the year. Increased in-stream flows contributed to protecting and restoring water-dependent ecosystems by increasing flow variability, end of system flows and flows to some anabranches.

Approximately 1,047 ML of Commonwealth environmental water was provided, consisting of:

• approximately 22 ML (unregulated) in the Severn River (Qld) in February 2016
• approximately 1,025 ML (unregulated) in the Macintyre and Dumaresq rivers (Qld) across flow events in July, August and November 2015 and in February 2016.

Environmental watering in the Severn and lower Macintyre River systems 2014-15

Status

30 June 2015: Completed

About the watering

Commonwealth environmental water was used to contribute to improving the ecological health and resilience of the Severn and lower Macintyre River systems. Commonwealth environmental watering occurred between December and April remained in-stream to contribute to protecting and restoring water-dependent ecosystems by supporting:

• increased flow variability
• episodically high ecological productivity and its ecological dispersal
• ecological processes dependent on hydrologic connectivity (i) longitudinally along watercourses; and (ii) laterally between watercourses and their floodplains (and associated wetlands).

Approximately 1,814 ML of Commonwealth environmental water was used as part of this watering action and consisted of:

• approximately 1,250 ML (unregulated) targeting the Severn River (Qld)
• approximately 564 ML (unregulated) targeting the lower Macintyre River (Qld)

Environmental watering in the Severn River (NSW) and Macintyre River 2013-14 (regulated)

About the watering

The overarching purpose of the action was to contribute to improving the ecological health and resilience of the Border Rivers system. 4 000 ML of Commonwealth environmental water was used in conjunction with 4 000 ML of NSW environmental water available under the ‘stimulus flow’ provisions of the NSW water sharing plan. The combined release of 8 000 ML, designed to mimic a natural spring ‘fresh’ flow, was made from Pindari Dam into the NSW Severn River in the second half of August 2013. The aim of augmenting the NSW release was to enhance the benefits of the ‘stimulus flow’ in the NSW Severn River and to enable in-stream benefits to extend further downstream into the Macintyre River than would have occurred without the additional Commonwealth environmental water.

The environmental outcomes of this watering action included:

• it achieved target peak flows and velocities required for tumbling of in-channel substrate to scour algae and reset benthic periphyton (biofilm) processes to support primary production
• it provided migration and dispersal cues to nativefish in the late winter-early spring period when species such as Murray cod are known to commence breeding activity in the Border Rivers. The timing of the action before the warmer spring and summer months was aimed to minimise cold water impacts on fish and other aquatic fauna
• observed flows wetted and interconnected riparian areas, wetlands and in channel benches in the NSW Severn River to provide hydrological connectivity and support nutrient and carbon cycling.
• residual flows from the action carried through the Macintyre River to the end of system (Mungindi) and were likely to have inundated low level benches in the lower Macintyre River, for some secondary nutrient and carbon cycling benefits.

Border Rivers catchment. Photo: Clare d'Arcy © CEWO

The watering action was made possible by the collaboration of a wide range of stakeholders including the NSW Office of Water, NSW DPI Fisheries, NSW Office of Environment and Heritage, Qld Department of Natural Resource and Mines, State Water Corporation, SunWater, Queensland Murray-Darling Committee and local water users and landholders.

Environmental watering in the lower Macintyre River systems 2013-14 (unregulated)

About the watering

A small volume (92 ML) of Commonwealth environmental water contributed to a small flow pulse in the Macintyre River in late March-early April 2013. This pulse peaked at around 4,000 ML/day at Goondiwindi and activated a few days of water harvesting (QLD) and supplementary (NSW) access in the Border Rivers main stem. The Commonwealth’s contribution could not be taken by other users with activated unregulated entitlements so it enhanced in-stream flows in the lower Macintyre River and the volume reaching the end of the system from this event.

There were no other unregulated flow events in 2013-14 that triggered unregulated access in the Border Rivers catchment, including in the Qld Severn River, where the Commonwealth also holds an unregulated entitlement.

Use of unregulated entitlements in 2013-14 was in line with the Commonwealth Environmental Water Holder’s decision in late 2012 for current and future holdings of Queensland unregulated entitlements to be used in-stream on an ongoing basis to enhance unregulated flow events. Over time in-stream use improves natural flow variability and restores some of the key flows (and associated ecological benefits) that were formerly extracted from the river during these events.

Border Rivers catchment Photo: Clare d'Arcy © CEWO

Environmental watering in the NSW Severn River and Macintyre River 2012-13 (regulated)

About the watering

Border Rivers catchment. Photo: Clare d'Arcy © CEWO

The environmental objectives of this watering action included contributing to:

• stimulating production through all levels of the aquatic food chain including aquatic insects, fish, platypus and bird life
• providing migration and dispersal cues to native fish
• wetting and interconnecting riparian areas and in channel benches.

895 ML of Commonwealth environmental water was used in conjunction with 4 000 ML of NSW environmental water available under the ‘stimulus flow’ provisions of the NSW water sharing plan and 7,105 ML of water that was being released to meet downstream irrigation orders. The combined release of 16 000 ML from Pindari Dam was designed to provide a high velocity high peaked flow in the NSW Severn River. The release commenced on 1 December and was delivered over 10 days. The large volume of irrigation water reduced the Commonwealth contribution (4 000 ML had been approved for the action).

Outcomes of the action included:

• peak flows in the Severn River, which exceeded 3,500 ML/day, were likely to be effective in souring rocks and gravel in the bed of the river to stimulate aquatic production.
• observed flows wetted and interconnected riparian areas, wetlands and in channel benches in the NSW Severn River to support nutrient and carbon cycling.
• Whilst extraction for irrigation use occurred along the Macintyre River, some residual flows from the release did carry through to the end of the system (Mungindi), where flows peaked at 800 ML/day in late December 2012. The Commonwealth contribution to the release helped in the extending the benefits of the ‘stimulus flow’ further downstream.

This watering action was made possible by the collaboration of a wide range of stakeholders including the NSW Office of Water, NSW DPI Fisheries, NSW Office of Environment and Heritage, Qld Department of Natural Resource and Mines, State Water Corporation, Queensland Murray-Darling Committee and local water users and landholders.

Environmental watering in the Qld Severn and lower Macintyre River 2012-13 (unregulated)

About the watering

A total of 1,663 ML of Commonwealth environmental contributed to unregulated flow events in the Border Rivers in 2014-15, comprised of:

• 687 ML in two flow pulses in the Macintyre River in late January-early February 2013 and June 2013.
• 976 ML in two flow pulses in the Severn River in late January and late February 2013.

The unregulated flow events in 2012-13 were large freshes to overbank flows in which Commonwealth environmental water is likely to have contributed to environmental outcomes including:

• providing a more naturally variable flow regime in the Severn River within Sundown National Park and the lower Macintyre system
• improving wetting of riparian vegetation and wetland connectivity
• improving habitat, movement and recruitment of native fish in the lower Macintyre River and within Sundown National Park, both areas of high fish diversity
• carbon and nutrient cycling through the system.

Use of unregulated entitlements in 2012-13 was in line with the Commonwealth Environmental Water Holder’s decision in late 2012 for current and future holdings of Queensland unregulated entitlements to be used in-stream on an ongoing basis to enhance unregulated flow events. Over time in-stream use improves natural flow variability and restores some of the key flows (and associated ecological benefits) that were formerly extracted from the river during these events.