Hunter River Salinity Trading Scheme 2024–25 Performance Report
The Scheme performed well in the year 2024–25 by maintaining the electrical conductivity (EC) levels in the river within the allowable range during the permitted industry discharge periods.
Summary
With the exception of Rix’s Creek Pty Limited, participants managed their onsite water within the regulatory framework, only discharging during available opportunities.
While there were limited discharge opportunities across all sectors in the first half of the financial year, the wet conditions and subsequent flows from Hunter River tributaries in the second half of the year meant that many opportunities to discharge were provided to scheme participants. In addition to the significant natural flows which occurred in the catchment, participants were able to benefit from the managed releases from the Flood Mitigation Zone of Glenbawn Dam conducted by WaterNSW. This release was carried out with a considered approach to increase flow with the added benefit of maximising the discharge opportunities available to participants.
In 2027, the EPA is commencing a review of the Protection of the Environment Operations (Hunter River Salinity Trading Scheme) Regulation. The review will include an investigation of the Scheme’s operations under extreme weather events to ensure effective ongoing management of salinity in the Hunter River, and will include reviewing the river sector (upper, middle, lower) salinity target levels.
This report covers the financial year period from 1 July 2024 to 30 June 2025. The report captures the Hunter River’s conditions throughout the year, the opportunities for industry discharges, those opportunities which were used and the salinity of the river during and outside of discharge opportunities.
WaterNSW are the Scheme’s Services Coordinator – the operator of the Scheme’s water model and telemetry network. Follow the link to read WaterNSW’s latest Annual Report.
The Scheme performed well in the year 2024–25 by maintaining the electrical conductivity (EC) levels in the river within the allowable range during the permitted industry discharge periods.
Rainfall variability in the 2024–25 financial year was high. In 2024 there were few large rain events and opportunities to discharge however a once in 500-year event in May 2025 brought torrential rain with more than 300 mm falling in parts of the catchment. The event triggered major flooding with significant inflows into Glenbawn and Glennies Creek dams and prolonged flows in the Hunter River extending though to June 2025. This resulted in more discharge opportunities for scheme participants compared to the 2023–2024 financial year. In total, there were 62 days representing 165 discharge opportunities where scheme participants were permitted to discharge to the Hunter River over the 3 river sectors.
Scheme participants were compliant with the scheme rules apart from Rix’s Creek Pty Limited, a non-discharging participant. In June 2025, Rix’s Creek Pty Limited reported a discharge from an uncapped borehole. In September 2025 the EPA fined them $30,000 for the water pollution incident. More details are available in the EPA media statement.
The Scheme performed well during the 2024–25 financial year. Electrical conductivity (EC) levels in the river were within the allowable range throughout discharge access periods. Widespread rain fell in the catchment, predominantly in the last quarter of the year, totalling 600-900mm. This resulted in significant inflows entering the Flood Mitigation Zone (FMZ) of Glenbawn Dam, which reached record high levels during May 2025.
Table 1 below shows a breakdown of the participants and their discharge status for the 2024–25 financial year. There were 16 Scheme participants. During this time, 6 participants discharged, and 10 did not discharge, 2 of which do not hold a discharge licence, and therefore cannot discharge.
Table 1 Hunter River Salinity Trading Scheme participants 2024–25
| Sector | Participant | Facility Name/ Discharge Location | Status |
|---|---|---|---|
| Upper | AQC Dartbrook Management Pty Ltd | Dartbrook Coal Mine | Discharger (inactive) |
| Upper | Hunter Valley Energy Coal Pty Ltd | Mount Arthur Coal | Discharger (inactive) |
| Upper | Bengalla Mining Company Pty Ltd | Bengalla Mine | Discharger (active) |
| Upper | Mangoola Coal Operations Pty Ltd | Mangoola Coal Operations | Discharger (inactive) |
| Upper | Mach Energy Australia Pty Ltd | Mount Pleasant Operation | Discharger (inactive) |
| Middle | HV Operations Pty Ltd | Hunter Valley Operations (Parnells Dam) | Discharger (inactive) |
| Middle | HV Operations Pty Ltd | Hunter Valley Operations (Dam 11N) | Discharger (active) |
| Middle | Liddell Coal Operations Pty Ltd | Liddell Coal Operations | Discharger (inactive) |
| Middle | AGL Macquarie Pty Ltd | Bayswater Power Station | Discharger (active) |
| Middle | Mt Owen Pty Ltd | Mount Owen Mine | Non-discharger |
| Middle | Ravensworth Operations Pty Ltd | Ravensworth Mining Complex | Discharger (active) |
| Lower | HV Operations Pty Ltd | Hunter Valley Operations (Lake James) | Discharger (active) |
| Lower | Wambo Coal Pty Ltd | Wambo Coal | Discharger (active) |
| Lower | Verdant Earth Technologies Ltd | Redbank Power Station | Discharger (inactive) |
| Lower | Bulga Coal Management Pty Ltd | Bulga Coal Complex | Discharger (inactive) |
| Lower | Warkworth Mining Ltd | Warkworth Coal Mine | Discharger (inactive) |
| Lower | Mount Thorley Operations Pty Ltd | Mount Thorley Operations | Discharger (active) |
| Lower | Rix’s Creek Pty Ltd | Rix’s Creek | Non-discharger |
There were 5 discharge events triggered in the year, with the longest event in May–June 2025 resulting in the most registers. A total of 80 registers were published throughout 2024-25 period, including 14 registers that were revised to increase the total allowed discharge due to higher than expected rainfall. The first event was triggered on 19 August 2024, with 5 river registers published, while the fifth and final event was triggered on 19 May 2025 with a total of 51 registers published.
The lower sector had the opportunity to discharge 62 times, the middle sector had the opportunity to discharge 52 times, and the upper sector had the opportunity to discharge 51 times.
Table 2 below shows the breakdown of discharge opportunities and events per sector.
Table 2 Breakdown of discharge opportunities and events in 2024–25; includes total number of times a sector credit factor was applied to restrict discharge
| Sector | Opportunities | Opportunities taken | % of Opportunities Taken | Sector Credit Factor (<1) applied |
|---|---|---|---|---|
| Upper | 51 | 1 | 1.9% | 8 |
| Middle | 52 | 42 | 81% | 2 |
| Lower | 62 | 18 | 29% | 0 |
| Total | 165 | 61 | - | 10 |
Sector Credit Factor
The credits held by each sector of the Hunter River entitle the sector to a percentage of the TAD. In certain blocks this means a permitted discharge could exceed the sector EC target. In those circumstances, a sector credit factor of <1 is applied to the sector, moderating the salt load discharged per credit to maintain the sector’s salt load below sector EC targets.
In 2024–25, a sector credit factor of <1 was applied 10 times. The reduced sector credit factor did not appear to impact discharge opportunities. Despite a reduced sector credit factor being applied eight times in the upper sector and twice in the middle sector, no discharges occurred during these periods.