A year in the Border Rivers catchment: 2024–25

Natural rainfall and river operations achieved a range of ecological outcomes in the Border Rivers system in 2024–25.

Key outcomes

Under moderate conditions, natural flows in the catchment met many environmental demands, resulting in:

• continuous connection to the Barwon River for the whole year
• multiple flow events in the Boomi River across a range of flow categories, including small and large freshes
• flow in Morella Watercourse and a top-up of floodplain wetlands.

Catchment conditions

During 2024–25, rainfall in the Border Rivers region was variable, with average to above average rainfall in most months. Rain occurred in the western region in November, leading into an average, dry 2024–25 summer. Rain in March and April was above average in some areas. This resulted in significant inflows of 39 gigalitres into Pindari Dam during April and large in-channel flows in the whole river system in 2025.

This widespread rainfall and high flows met many environmental demands. Delivery of additional water for the environment was not needed, in a year where the stimulus flow was not triggered and water in dams could be saved for drier periods.

Partnering with Aboriginal peoples

Water for Country represents the planning and delivery of environmental water by the Department of Climate Change, Energy, the Environment and Water in collaboration with Aboriginal people across New South Wales. This work continues to progress, supporting ecological outcomes while also protecting and revitalising cultural places, values and interests.

To support these outcomes in the 2024–25 water year, environmental water managers used accounts to enable a larger portion of water from natural events to remain in the system.

Water managers and the Water for the Environment Branch are building relationships with the Gamilaraay (Kamilaroi) people in the Border Rivers region to understand the cultural significance of the Border Rivers region and Macintyre River floodplain. During 2024, a report on cultural values of the region was developed for inclusion into the Border Rivers Long-Term Water Plan.

In 2025, community members and staff participated in a National Indigenous Mapping Workshop as part of the Reconnecting Watercourse Country Program. These activities are building toward a more collaborative, continued relationship.

Watering aims

The annual environmental water priorities in the Border Rivers catchment 2024–25 were developed under predicted dry to moderate weather and water availability.

The El Niño–Southern Oscillation outlook was neutral and predicted to persist. Aims for the use of water for the environment were to reserve water in dams for potential dry conditions, and respond to or enhance natural events for the benefit of:

• native fish populations in the Severn, Dumaresq, Macintyre and upper Barwon rivers
• fish breeding, recruitment, and connectivity if conditions eventuate.

Water managers planned to deliver a small fresh to support native fish if the planned environmental water stimulus flow became available. However, the stimulus flow was not triggered in 2024, so water in this account has been carried over.

Rainfall and the resulting natural flows:

• maintained ecological health and resilience
• maintained key floodplain wetland habitat
• provided opportunities for plants and animals to breed, move and persist throughout the catchment.

Water delivery

There was no environmental water released from Pindari or Glenlyon dams this year. Flows were protected throughout the catchment in regulated and unregulated watercourses.

This table and chart provide a summary of 1,284 megalitres of Commonwealth Environmental Water Holder supplementary water for the environment protected in the Border Rivers catchment during the 2024–25 water year. This enhanced natural flows by ensuring these volumes were not extracted from natural events.

The Pindari stimulus flow was not triggered for use. This resulted in a full account of 8,000 megalitres to be released when the trigger occurs in the 2025–26 water year. Daily minimum releases provided flows from Pindari Dam throughout the year, supporting flow in the downstream system for about 75% of the year.

The Boomi River replenishment flow was delivered by WaterNSW via the Boomi River offtake for 3 weeks in February. A natural pulse also entered the river due to large flows in April. It is likely that the Boomi River connected to the Barwon River on these occasions.

Figures were accurate at the date of publishing but may be adjusted. The watering event number in the table and chart relate to the location number marked on the map.

_{Notes: CEW = Commonwealth licensed environmental water.}

Outcomes

Environmental watering targets have been developed for the catchment through the NSW Border Rivers Long-Term Water Plan.

Analysis of these targets for 2024–25 indicates that some of the water flow goals that held environmental water could help achieve were met. Low water flow targets were not always met and usually did not last long enough in the seasons they were needed. Small and large freshes were sometimes met.

Supplementary access was announced on 24 occasions during 2024–25, with irrigators using 51 gigalitres. The water sharing plan aims to mitigate the alterations to medium and high flows by protecting 25% of supplementary water events for the environment, measured at Mungindi.

The use of 1,284 megalitres of Commonwealth Environmental Water Holder NSW Border Rivers supplementary water was protected from the Border Rivers into the Barwon River. This protection was maintained by active management rules as the water moved down the system. The flow events:

• enhanced inter- and intra-valley connectivity during natural events
• helped provide greater access to a range of habitats for water-dependent species
• improved breeding, dispersal and recruitment opportunities for native fish.

Significant events during the year included:

• a large rainfall event in the west during November, which caused inundation and improved soil moisture
• very high rainfall in the east of the catchment in March and April, which resulted in high autumn flows throughout the catchment, flows in Morella Watercourse and Boomi River, and opportunities for aquatic and floodplain species to complete all or part of their life cycles.

Along with the Commonwealth Environmental Water Holder, we participated in the WaterNSW Customer Advisory Group for the Border Rivers. Environmental water managers are important participants in this group, which represents members from across the catchment including many water-user groups.

Case study: do rules do the job at Pindari?

Pindari Dam regulates the NSW Severn River. When water is released from the dam, the river regains some of its naturalness at tributaries that join further downstream. This occurs at Frazer’s Creek, the Macintyre and Dumaresq confluences. The most severe impact on river flows occurs closest to the dam.

The water sharing plan for the regulated NSW Border Rivers has a minimum flow rule for Pindari Dam, which ensures cease-to-flow conditions don’t arise in the NSW Severn River. The rule requires at least 10, 50 or 200 megalitres/day to be released from Pindari Dam, depending on dam inflows and the time of year.

The NSW Border Rivers Long-Term Water Plan includes environmental water requirements that guide the management of water, such as a baseflow per day, to achieve ecological outcomes for the assets and functions of the waterways.

Downstream of Pindari Dam, environmental water requirements have been developed for the Severn River at Ashford gauge. Flows at this gauge have been assessed to see if water sharing plan rules, and other flows, are able to meet the baseflow of 65-245 megalitres/day. Findings showed that minimum flow releases were unable to meet the baseflow for the duration required. This was because minimum flow releases contributed from Pindari Dam were only large enough in June, July and August.

The environmental water requirements call for 224 days of baseflow at Ashford in moderate to wet years. Tributary flows and dam releases over the irrigation season contribute to these baseflow days. This is helpful for the seasonal aspect, but may not achieve the total baseflow days required, especially in the ecologically productive months of spring.

Using environmental water to maintain a baseflow in spring, combined with initiatives to address Pindari Dam stratification and cold water, could create significant benefits for native fish in this reach.