Update - August 2025: WaterNSW has paused the Warragamba Dam Environmental Flows Project following IPART’s draft pricing determination. The project will not be proceeding at this time. WaterNSW remains committed to meeting our customer obligations and supporting the communities we serve, and will review future priorities when able to do so.
Frequently asked questions
What is an environmental flow?
An environmental flow, sometimes called an e-flow, is when water is released from a dam or weir to mimic natural river flow patterns by passing a portion of inflows from the dam downstream. These releases help to maintain downstream river health and support the environment.
The environmental proposed for Warragamba Dam would vary from day-to-day depending on the amount of water flowing into Lake Burragorang, and can be sourced from different water depths to allow release of optimal water quality.
Do environmental flows cause flooding?
No. Environmental flows are carefully planned, controlled releases that do not cause or contribute to flooding and flows would be contained within the river banks . These releases are designed to mimic natural flow patterns, but at levels that are safe and below flood thresholds.
Will environmental flows raise the water level near my property?
No. Environmental flows are typically small, gradual releases to maintain river health. They are not large flood releases, and do not cause sudden or extreme rises in water levels.
Can environmental flows damage my property, infrastructure, or farmland?
No. Environmental flow releases remain within the river channel. They do not exceed safe flow levels and would be released in coordination with weather forecasts, to make sure flows do not coincide with flood conditions.
Are environmental flows different from flood releases? Can they make flooding worse if there’s already heavy rain?
Environmental flows are different from flood releases as they are small, regular flows to maintain ecological health. Flood releases are actions taken to manage natural rainfall events, protect dam safety and reduce flood risks. Environmental flows are not flood releases and differ in purpose and scale.
Environmental flows are managed by using weather and river data and would not operate during flood events.
Would the environmental flows project affect local emergency management?
The release of E-Flows will be carefully managed in consultation with relevant emergency management agencies in the event of downstream flooding. They would also not operate if the dam was in flood management mode and releasing water down the spillway.
Would the environmental flows project affect water security?
Environmental flows have been developed to ensure they do not compromise Sydney’s drinking water supply or overall water security. The amount of water released each day depends on how much water is flowing into the dam and how full the dam is at the time.
How will environmental impacts be assessed before construction of the environmental flows can begin?
The project is classified as State Significant Infrastructure and will require an Environmental Impact Statement. This statement will evaluate potential environmental impacts and benefits, including biodiversity, water resources, heritage, First Nations, social, and economic issues. The statement will be displayed for public review, and submissions will be invited.
The Environmental Impact Statement will consider impacts during both the construction phase and once the environmental flows project is operational. Interested stakeholders and community will be consulted throughout the project’s Environmental Impact Statement process.
Stakeholders including local residents, environmental groups, and industry representatives, will be consulted to provide input on the project’s development.
WaterNSW is committed to engaging with First Nations communities on the Warragamba Dam Environmental Flows Project to recognise cultural values related to the river and water flows and incorporate traditional knowledge into planning and management decisions.
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