The Border Rivers catchment encompasses the Queensland–New South Wales border, with about 50% of its area in each state, covering 24,000 square kilometres in total. The New South Wales Border Rivers catchment includes numerous anabranches, waterholes and wetlands on a semi-arid floodplain in a relatively low rainfall zone. The catchment is influenced by management of water on both sides of the border.
Severe drought conditions have been present in the region since mid-2017. In late 2019 the region remained in drought. Although rainfall occurred in early 2020, the catchment condition is still considered dry.
A flow from Glenlyon Dam was delivered in late 2019 to replenish Boggabilla Weir pool for town water supply. Following deliveries from Glenlyon Dam were deemed unviable due to the limited volume remaining in storage. Delivery of minimum daily flow requirements continued from Pindari Dam, but these only maintained flow to Ashford.
The Northern Fish Flow in early 2019 helped maintain some of the refuge pools through to February and March 2020 when significant rainfall occurred in the Border Rivers catchment. This resulted in uncontrolled flow events that restored connection along the Border Rivers and to the Barwon River. Since then flows have been maintained across the Border Rivers by subsequent smaller rainfall events and continued tributary inflows.
A flexible approach
During the severe dry period, the NSW Department of Primary Industries – Fisheries set up Valley Technical Advisory Groups to advise on potential drought response actions for aquatic ecosystems of the Border Rivers. These actions included refuge pool identification and inspection, fish rescues and water quality monitoring.
The planned Pindari stimulus flow was not triggered for the 2019–20 season and no releases were made under the translucency rules despite inflows being received from February to June. Translucent flows were not delivered due to valve maintenance requirements and the undelivered volume has been deferred for use in the 2020–21 water year. If inflows continue into 2020–21, translucent flows may occur from Pindari Dam. Planning is under way for the delivery of the 2020–21 Pindari Stimulus Flow and Commonwealth Environmental Water Holder held environmental water in Pindari Dam.
The focus of water managers in 2019–20, with an expected very dry to dry resource availability scenario as identified in the NSW Border Rivers Catchment Annual Environmental Watering Priorities 2019–20 was to adopt a flexible and responsive approach. This approach acknowledged natural cues and the need to meet the water needs of the environment across a range of systems and climatic conditions.