In 2021–22 environmental water managers worked with stakeholders and the community to deliver flows to target areas across the catchment to support waterbird breeding, native fish, vegetation and connectivity.
Water from all environmental sources was accessed this year including NSW and Commonwealth Environmental Water Holder (CEWH) allocations. The first managed delivery was in July 2021, when CEWH supplementary water was activated to keep more water in Carole Creek to increase connectivity to instream anabranches and downstream to the Barwon River. This event was repeated in June 2022, this time using CEWH high security water from Copeton Dam.
Over spring and summer general security CEWH water was delivered into Mallowa Creek to support waterbirds and wetland vegetation communities. During this event we monitored frogs and, in collaboration with the CEWH monitoring, evaluation and research program (Flow-MER), vegetation and waterbirds. Monitoring revealed these plant and animal communities responded positively to this delivery, although their post-drought recovery was not as high as that observed in similar communities in the Gingham and Lower Gwydir wetlands.
In early 2022 in collaboration with a local irrigator, NSW general security water was delivered to Whittaker’s Lagoon, which is only connected to watercourses during large floodplain flooding. This delivery supported a range of waterbird species including dusky moorhen and white-necked heron nesting. Several semi-permanent vegetation species and frogs completed their life cycles with the delivery of this water.
Following natural flows and triggers, a large-scale breeding event involving an estimated 45,000 pairs of colonial-nesting waterbirds occurred over summer in the Gingham and Lower Gwydir watercourses. After flows receded, approximately 28.4 gigalitres (GL) of NSW and CEWH held and planned water was delivered from Copeton Dam to support the event. This was in addition to 28.6 GL of other flows, including further planned water. Colonies were monitored in collaboration with Flow-MER and flow rates adjusted as needed. Delivered water supported vegetation during the breeding event.
Advice was sought from the Gwydir Environmental Water Advisory Group following significant flows in the catchment. Over autumn and winter planned environmental water that would usually be directed towards Gingham and Lower Gwydir was directed towards the Barwon River via Mehi River and Carole Creek. This action was considered appropriate because of the significant inflows and waterbird breeding was mostly completed by this time.