Performance of the Hunter River Salinity Trading Scheme

The Scheme has proved tremendously successful and is widely supported by the community that contributed to its creation.

The EPA administers the scheme with guidance from an operations committee with representatives of the community, industry and the government. The scheme uses a market-based instrument to successfully address a serious environmental problem.

Performance summary: 2020–21

During the 2020-21 financial year, the Hunter River catchment received higher rainfall when compared to recent years, resulting in high flows and allowing the Scheme to safely discharge salty water into the Hunter River. The map below identifies the locations of each sector of the Hunter River referred to in the Scheme.

Hunter Valley map

Five discharge periods (known as blocks) were activated in 2020–21, providing 63 discharge opportunities for various industries, with 28 discharge opportunities for the Upper sector, 15 for the Middle sector, and 20 for the Lower sector.

In total, there were 98 individual discharge events of saline water from across 8 industry sources into the river in 2020-21, within the 63 discharge opportunities.

Performance during industry discharge events

A total of 10,000 tonnes of salt were discharged to the Hunter River by Scheme participants during high flows, representing 7% of the Total Allowable Discharge (TAD) of salt per year, and 18% of the total salt load carried by the river past Singleton in 2020–21. Eight participants took advantage of discharge opportunities. The calculated TAD (i.e. without flood flows) was 151,900 tonnes. The average daily salinity in the river over the 2020–21 period was 650 µ/cm at Denman; 855 µS/cm at upstream Glennies Creek; and 742 µS/cm at Singleton.

Performance reports

Each year the EPA assesses and reports on the performance of the scheme.

Longer-term scheme performance

While the scheme operates to manage salinity levels in the river as a result of industry discharge, occasional exceedances still occur, caused by diffuse sources of saline runoff. New mines can readily be granted discharge licences, with significant economic and employment benefits for the valley.

However, since the scheme started, river salinity has more consistently been below the salinity target.

These improvements have occurred since higher average rainfall has occurred after the scheme began, granting scheme participants more discharge opportunities and maintaining salinity targets.

The graph below shows that in previous dry spells (in the early 1980s and 1990s) average salinity levels were very high. These have not been repeated during the time since the scheme commenced.

Monthly Average Electrical Conductivity at Singleton 1980 to 2002


The graph below shows the yearly average electrical conductivity at Singleton between 1993 to 2022. It shows that the average EC was higher in the period before the commencement of the Regulation in 2002 while average EC has stayed well below the target since the commencement of the Regulation.

Chart showing Annual Average Electrical conductivity at Singleton 1993 to 2022