FAQs

A dam is a barrier or structure built across a waterway to obstruct and control the flow. Dams vary in size from small earth embankments, often for farm use, to large concrete structures. Dams Safety NSW regards the following structures as dams:

• dams
• weirs
• off-river storages
• retarding basins
• reservoirs
• tailings dams.

Dams Safety NSW assesses all dams in NSW and determines dams that can potentially endanger life downstream, cause major damage or loss to infrastructure or the environment, or have major health and social impacts. These are referred to as declared dams. 

Each declared dam has a consequence category that reflects its potential risks. Sydney Water is required to address any risk concerning our the safety of our dams in accordance with the Dams Safety Act 2015 and the Dams Safety Regulation 2019. 

These provide the framework and activities that ensure dams don't put the safety of persons, property or the environment at risk. 

Each year we produce a Dams safety standards report for each of our declared dams – see the latest summary (201 KB). For more information or complete reports, email damsafety@sydneywater.com.au.

We work in partnership with Water NSW, which supplies much of the untreated raw water from rivers and dams. Water NSW manages eleven major dams and reservoirs (21 declared storage dams) that provide drinking water to Greater Sydney.

Our 16 declared dams

Only reservoirs that are built into the ground with earth embankments, which provide support to the structure, are declared as dams. Most of Sydney Water’s reservoirs are above ground concrete or steel structures, and pose no threat to the community. All reservoirs are regularly inspected to ensure structural integrity.

The Dams Safety Regulation 2019 sets out operational details and safety standards that declared dam owners must comply with to satisfy the provisions of the Dam Safety Act 2015.

The regulation states that dam owners must establish and implement a dam safety management system.

The current version of the Act commenced in 2015 (originally introduced in 1978), the regulation commenced on 1 November 2019 with the introduction of Dams Safety NSW as the regulator, replacing the previous Dams Safety Committee.

Our dams must be safe, so we can protect people, property and the environment around the dams we manage. We rely on the dams to store water for our customers so we need to comply to this regulation to ensure we continue to provide world class services for our customers. 

Our dams also provide community infrastructure and recreational space, so we need to ensure that these are safe and reliable and do not cause any disruption to neighbouring communities.

The regulation ensures the best standards to maintain our Dams. We have internal/ audits and inspections that identify what  actions we need to take to meet the requirements of the legislation.

Dams Safety NSW is responsible for monitoring our compliance with dam safety legislation. 

Dams Safety NSW exercises a range of proactive, planned compliance activities with declared dam owners, including:

• running a risk-based audit program with compliance priorities determined by dam consequence category and other risk factors
• risk-based inspections.

The legislation aims to ensure that key dam safety activities are undertaken and reviewed by organisations with appropriate competencies. This will strengthen the dams safety standards so that we minimise risks associated with dams and provide a strong level of safety acceptable to the community.

The Dam Safety  Regulation 2019 and associated Australian National Committee on Large Dams (ANCOLD) standards specify that there must be no trees and shrubs above one metre on dam embankments and within five metres of the base (toe) of the embankment. The embankment is a structural part of the dam and must not be compromised.

The decision to clear vegetation was made in accordance with these standards. This will enable Sydney Water’s technical and engineering teams to effectively assess ground, below ground and structural conditions of our dam and minimise safety and operational risk.

Regular maintenance of dam embankments is required to ensure slope stability and to permit observation of any cracking, piping, sliding or seepage. Vegetation, including trees and shrubs, can have the following impacts: 

•  The roots can dislodge joint fillings and penetrate cracks in concrete walls or foundation rock possibly leading to crack widening and concrete or rock deterioration resulting in increased leakage.
• Decaying roots can provide pathway for water movement and cause erosion, or a leakage in concrete walls or rock foundations.
• Vegetation can absorb and transpire substantial amounts of water and, therefore, could prevent early detection of water leaking through cracks and joints in the wall or foundation. 
• Toppling of trees during windstorms can cause damage to the embankment, wall or foundation if substantial material is dislodged with the root system. 
• Trees and large shrubs limit access and visibility, and prevent effective inspection for early identification of structural issues.

There will be no replanting of trees on dam embankments, or within five metres of the embankment base. However, where appropriate, we  will work with local Councils to provide some offset planting. This planting will be within the same local government area, and possibly within parks, but further away from dam embankments. .

The cleared areas will be covered by turf, and will be maintained in accordance with the vegetation standards for our dam assets. This will enable us to regularly inspect and maintain our dams.

For further information on Dams, visit Dams Safety NSW 

For information on Sydney Water visit sydneywater

For  Dams safety standards report download  summary (201 KB).

 For more information or complete reports, email damsafety@sydneywater.com.au.