The Commonwealth Environmental Water Holder (CEWH), with the support of the Commonwealth Environmental Water Office (CEWO), manages a large and diverse portfolio of water entitlements across the Murray Darling Basin (the Basin) for the purposes of protecting or restoring environmental assets. To ensure management across the Basin supports the Commonwealth Government’s obligations set out in the Murray-Darling Basin Watering Strategy (BWS), the CEWO has a planning framework that prioritises the needs of environmental assets (demand) against water availability (including supply of Commonwealth water and catchment conditions). Key adaptive management principals are also used to inform and monitor environmental water decisions.
The Border Rivers catchment, located at the top of the Basin in southern Queensland and northern NSW, supports a diverse range of threatened native fish species. However, this catchment has experienced several years of low flow conditions, which was likely to have impacted native fish population resilience. Also, the supply of environmental water was unlikely to support spawning and recruitment, when required. To address this, the CEWO worked with state agency scientists to apply adaptive management strategies. Habitat mapping was undertaken to determine minimal and optimal environmental watering requirements for a range of fish guilds. A fish and flows intervention monitoring project was undertaken to determine the health of native fish populations and allow for the evaluation of environmental watering. Scientific and operational advice was also used to evaluate and mitigate possible ecological risks, including cold water pollution.
The adaptive management strategy successfully enabled the development and implementation of effective watering actions for the Border Rivers. This strategy lead to the recruitment of Murray cod in a reach where recruitment had not been observed for five years. Implementation of the watering actions also highlighted the challenges of working within operational constraints of a modified system.