Annual environmental water priorities in the Gwydir catchment

Water managers will take a proactive approach to watering events in the Gwydir catchment, targeting whole-of-system health.

Priorities for 2018–19

A warm, dry season is forecast for the Gwydir catchment. While the availability of planned water for the environment is likely to be low, reserves of held Commonwealth and NSW water, along with carryover, are moderate to high.

To maintain the resilience of wetlands and rivers, water managers will take a proactive approach to managed watering events. This approach aims to address the decline of wetland communities in the western Gingham and Lower Gwydir Watercourses and Mallowa Creek watercourse.

Flows into the Gingham and Lower Gwydir Watercourse systems and Mallowa Creek watercourse will support wetland vegetation communities, waterbird diversity and populations, threatened native fish populations and the inundation of eastern Gwydir Ramsar sites, as well as providing instream benefits to the Gwydir and Mehi rivers.

Currently, there are no plans to provide connectivity to the Barwon River. Environmental water may be used in the Mehi River and Carole Creek to maintain refuge pools for native fish if block release operations in these systems are required this season. 

Further details on watering priorities for 2018–19 can be found in the Annual Environmental Watering Priorities 2018–19 (PDF 2.1MB).

Highlights from 2017–18

The Gwydir catchment and floodplain, west of Moree, experienced low water availability and a mostly dry water year in 2017–18.

Water manager Daryl Albertson said natural flow triggers formed the basis of water delivery during the season. Two natural flows occurred – one small event in July and a moderate event in October 2017.

Early season rain events in the upper catchment provided inflows into Copeton Dam. This triggered a ‘stimulus flow’ – a release of water designed to mimic a series of small ‘freshes’ (or pulses) in the river downstream. This ‘stimulus flow’ occurred in late winter and early spring, priming the system ahead of the warmer months.

Stable fish flows were also delivered into the Mehi and Gwydir rivers and Carole Creek systems from October to November 2017. These flows built upon the previous early season stimulus flow and supported native fish recruitment in a period between high volume irrigation releases, when river flows were low.

In the Gwydir River system, managed flows from December 2017 to January 2018 restored a more natural flow regime. The Gingham and Lower Gwydir watercourses system was the main target for this flow, assisting and extending ecological processes.

Water for the environment was delivered in April 2018 from the Gwydir River via the Mehi River and Carole–Gil Gil creeks to provide inflows from the Gwydir system into the Barwon River to contribute to the Northern Basin connectivity event for the Barwon–Darling system. This flow connected these northern rivers, improved water quality, and provided habitat and food sources for native fish populations, both in the flow delivery path of river and creek sections of the Gwydir and then along the Barwon-Darling river systems.