The Gwydir valley catchment extends from the Northern Tablelands to the Northern Plains, where it joins the Barwon River, covering an area of 26,596 square kilometers. The Gwydir River system and its wetlands are located on a semi-arid floodplain, in a relatively low rainfall zone. This influences decision-making around water for the environment.
Since the summer of 2016, the Gwydir catchment has experienced an extended hot and dry period, with limited rainfall and low natural flows. At the beginning of this water year, the catchment was in a very dry state. These conditions prevailed throughout spring and summer 2019. Rainfall and river flows finally returned to the catchment system in February 2020.
Protecting key assets
The focus of water managers in 2019–20, with an expected very dry resource availability scenario, as identified in the Gwydir Catchment Annual Environmental Watering Priorities 2019–20, was on protecting key water-dependent assets, such as native fish communities. Water for the environment was used to support the resilience of local rivers to ensure they were ready to respond when rain and river flows returned to the catchment. This approach protected fish communities in priority river reaches in the Carole Creek, Mehi and Gwydir rivers from complete drying. In early 2020 much wetter than expected conditions enabled environmental deliveries to the Gwydir wetlands.
A conservative planning approach taken over preceding seasons meant there were remaining reserves of water for the environment at the beginning of the 2019–20 water year.
Significant water for the environment outcomes included deliveries made to keep fish communities alive in these river reaches in the system, commencing in October 2019 through to January 2020.
A small delivery was made to Whittaker’s Lagoon, on the Mehi River floodplain, that served as key habitat and resources for water-dependent local native animals, during the extended dry period.
When rains and river flows returned to the system in early 2020, water managers delivered water for the environment in combination with natural flows into the downstream Gwydir Wetlands, inundating about 3500 hectares of core wetland habitats and communities.