The Macquarie Cudgegong Environmental Water Advisory Group met in Dubbo on 18 February 2025 to review the 2024–25 water year outcomes and identify preliminary watering objectives for the 2025–26 water year.
Region updates
Members shared updates on the conditions observed in the catchment. Common observations included significant summer storms within a moderate to dry rainfall season.
The group discussed the effects of these storms on fish breeding and other benefits for the river ecosystem. For example, organic matter washed into rivers boosts the food supply for native fish, platypus, and other aquatic animals.
Catchment conditions
Rainfall across the region was generally average. The Bureau of Meteorology forecasts median temperatures and rainfall for the next 3 months, leaning toward a warm and median to wet autumn.
Burrendong Dam's minimum inflows were approximately 388 gigalitres over the past 7 months.
The WaterNSW drought flood risk index is 'normal' but trending toward dry. At the time of the meeting, water stored in Burrendong Dam was at 55% of capacity, with Windamere Dam at 90%.
Overview of outcomes
Wetland vegetation
The targets set by the Environmental Water Advisory Group for the 2024–25 year included an inundation target of over 20,000 hectares in the Macquarie Marshes. Satellite mapping suggests this target was well exceeded, with 37,000 hectares inundated. Visual observations indicate many areas of wetland vegetation are in medium to good condition, which is promising for next year.
Native fish
An autumn flow pulse is planned in the Wambuul-Macquarie River to enhance juvenile fish survival and allow recruitment into the adult population. This complements the environmental water events in spring 2024 and summer 2024–25 to improve breeding conditions for fish downstream of Warren, particularly in-river specialists, such as Murray cod and freshwater catfish, who nest in the river in warmer temperatures.
In the Cudgegong River, a spring pulse occurred in October and November 2024, followed by a period of elevated base flow to assist native fish breeding and recruitment.
Heavy local rain below Windamere Dam in December 2024 saw high river flows that broke out of the banks and drown-out instream barriers, providing a brief opportunity for native fish to move along the Cudgegong River.
Waterbirds
The spring 2024 pulse inundation of the Macquarie Marshes using water for the environment provided excellent feeding and breeding conditions for a range of waterbirds, including magpie geese, brolgas, glossy ibis, many ducks, waterhens, and the endangered Australian painted snipe and Australasian bittern.
Mass breeding of group-nesting species like ibis and egrets was not expected given the moderate conditions, and none were detected. Many of the major group-breeding sites were inundated over spring, and they remain in 'event ready' condition for the next major breeding event.
Planning ahead
Water for the environment still in accounts will secure flows for the future, including:
- approximately 9,116 megalitres (ML) for the Cudgegong River in the environmental water allowance
- at least 175,000 ML for the Wambuul-Macquarie River (mostly general security licences and environmental water allowance).
Based on a review of current water availability and potential environmental demands, the group considered planning actions to maintain current conditions.
Preliminary priorities were identified, including maintaining the condition of key waterbird breeding sites and supporting the recovery of native fish populations.
The group will meet again in May 2025 for a 2-day planning meeting to finalise watering objectives for the 2025–26 water year.