Pindari Dam trial targets cold water pollution impacts on native fish

Cold water pollution occurs when the bottom cold layer of water from a stratified dam is released into the river downstream resulting in an artificial drop in river temperatures during the warmer summer months. These cold discharges negatively impact inland rivers, reducing the breeding opportunities for native fish and suppressing growth which reduces the resilience of freshwater ecosystems.

WaterNSW will conduct a two-year trial at Pindari Dam on the Severn River in the state’s north in partnership with the Department of Primary Industries and Regional Development (DPIRD) Fisheries with funding support from the Commonwealth Government.

The trial involves installing a ‘bubble plume system’ to mix the water and create a more consistent temperature through the water column.

The project aims to improve downstream water temperatures by up to 10⁰C during summer which will aid in native fish recovery.

To obtain net zero emissions, a large solar farm will be constructed to power the compressors should the trial prove successful.

Pindari Dam was identified as a high priority for cold water pollution by the NSW Government as the reservoir is one of the deepest in the state.

Research from DPIRD Fisheries has identified that cold water pollution detrimentally impacts river ecosystems below major dams in the Murray-Darling Basin and contributes to native fish declines by limiting reproduction, growth and survival.

“Cold water pollution is a well-recognised issue associated with dam operations, especially the large supply dams that are typical to regional NSW,” a WaterNSW spokesperson said.

“Addressing the problem is an engineering challenge because dams were originally designed to release water primarily from the bottom, meaning the coldest water from the lower levels is often discharged.

“By using green-powered bubble plumes at a dam as deep as Pindari, we should get a good indication as to whether this technology will be effective at other priority locations across the state,” the spokesperson said.

The contract for the trial has been awarded to regional contractor Eire Civil Infrastructure who are due to start work today.

The project team has started early and inclusive conversations with local community members and key stakeholders, including local First Nations groups, to ensure a diverse range of voices and perspectives help shape the project.