Pindari Dam cold water pollution

What is cold water pollution?

Cold water pollution occurs when the bottom, cold layer of water from large dams is released downstream.

In large dams, 'strata layers' develop, where water near the surface of the dam is warmer than the water at the bottom. The valves used to release water are located near the bottom of the dam, to ensure water can be released when dam levels are lower. Releasing cold water downstream can drop the temperature in the river during the warmer months.

This drop in temperature can impact wildlife in the river by confusing natural cycles for growth and breeding, and increase mortality. For our native fish, cold water pollution is a key contributor to the loss of over half of the fish species that we would expect to see below the major dams in the Murray-Darling Basin.

About the project

The Australian Government has provided a $26.2 million investment for the Pindari Dam cold water pollution project. The project will support native fish and other acquatic life downstream of the dam.

The Pindari Dam cold water pollution projects will use bubble plume technology to move water within the dam, disrupting the strata layers. Large compressors deliver air to diffusers located near the bottom of the dam, and the rising ubble plume mixes the water. This will make the water temperature more even throughout the dam, reducing the impact of the water released downstream on the temperature of the river.

Pindari Dam is located within the Border Rivers catchment in the northern Murray-Darling Basin. It is one of eight dams that are a high priority in addressing cold water pollution in NSW.  Operational water releases from Pindari Dam can cause cold water pollution discharges that extend up to 200 km downstream to Goondiwindi. The main impacts are seen in the first 80 km of river below the dam.

WaterNSW and theNSW Department of Primary Industries Regional Development (DPIRD Fisheries) are working in partnership with the Australian Government to deliver the Pindari Dam cold water pollution project.

A graphic explaining the impact of a bubble plume on the layers of water in a dam.

When air is released through the diffusers, a rising bubble plume mixes the water. This provides consistent warmer temperatures throughout the water and in the water released downstream, rather than a warmer top layer and a very cold bottom layer.

View larger diagram

Benefits

The project aims to provide significant environmental, social, economic and cultural benefits to the northern Basin. Mitigating cold water pollution below the dam will:

  • improve native fish health downstream of Pindari Dam, particularly for Golden Perch and Murray Cod;
  • improve water quality through reservoir destratification that aims to increase dissolved oxygen levels while reducing soluble metal and nutrient concentrations and algal bloom frequency;
  • improve recreational opportunities (swimming, boating, fishing) within and downstream of Pindari Dam;
  • enhance ecological outcomes from the management of dam releases, including environment flows, as required under NSW’s water sharing plans and the Murray-Darling Basin Plan;
  • improve the health of key totem species including Murray Cod and Golden Perch that First Nations people have a custodianship duty to care for and protect;
  • contribute to net zero carbon emission targets.

Objectives

The project aims to:

  • improve downstream temperatures by up to 10⁰C
  • demonstrate the effectiveness of bubble plumes to de-stratify a large dam (Pindari) and mitigate CWP to strengthen the case to deploy this technology at the remaining high priority dams in the Murray-Darling Basin
  • employ a green energy solution to offset the high energy demand of the bubble plume system to ensure that ongoing operations are cost and carbon neutral. This will involve building a solar farm to power the compressors should the trial prove successful.

Schedule

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September 2023
Project initiation

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December 2024
Final detailed design

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July 2025
Award contract

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September 2025 - May 2026
Construction

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March 2026
Bubble plume system trial

Contact

For further information on the Pindari Bubble Plume Project, please email engagement@waternsw.com.au

WaterNSW acknowledges the traditional custodians of the lands and waters on which we work and pay our respects to all elders past, present and emerging. Learn more