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Enlarged Cotter Dam

This project by ACTEW Water achieved a 'Commended' As Built v1.0 IS Rating.


An Enlarged Cotter Dam is being built downstream of the existing dam to increase the Cotter Reservoir’s capacity from four gigalitres to 76 gigalitres. The Enlarged Cotter Dam forms part of ACTEW’s continued response to ensuring a secure water supply for the Australian Capital Territory, and to address drought, climate change and variability.

"Identifying a more sustainable and economically viable method of deriving the main materials for the dam from on site was a major sustainable delivery ‘win’. The commitment to sustainability through the development of the Sustainability Policy and the BWA Charter were based on the IS framework, and drove decision-making and the culture of the project team." 

Kirilly Dickson, Group Manager, Safety, Environment, Quality and Regulation (SEQR), ACTEW Water


  • Rating Type Water
  • Rating Score 40.9
  • Registered Date September 2012
  • Practical Completion January 2013
  • Jurisdiction Australia
  • States ACT
  • Suburb Cotter Dam
  • Assessor Ian Hustwick
  • Capital Value $299 Million
  • Other Stakeholders GHD, John Holland Group Pty Ltd

Rating Highlights

Management Systems

Man-1, Man-3, Man-4, Man-6 Level 2

Man-7 Decision Making, level 3

Good management systems in place

Sustainability incentivised through KPIs

Risk and opportunities are identified and assessed.

Sustainability opportunities were identified and tied to KRAs and KPIs.

You tube videos were developed to share sustainability knowledge with the public.

Procurement and Purchasing

Pro-1, Pro-2 Level 2

Implemented set of sustainability commitments as part of procurement process.

Sustainability was considered and addressed during supplier identification.


Wat-3 Level 3

100% of potable water use has been replaced by non-potable water.

The location of the existing dam onsite provided a readily available source of non-potable water to the project.

UV technology was used to treat dam water to drinking water for site workers and offices.


Mat-1 Level 3

Through optimised design materials choices the project achieved a significant reduction in the lifecycle environmental impact of materials use reducing embodied carbon emissions by 23% (37,000 tCO2e) and ecopoints by 28%.

This was primarily achieved through increasing fly ash content in concrete and sourcing aggregates from on site.


Discharges to Air, Land & Water

Dis-1, Dis-4 Level 2

Dis-3 Level 3

For all ‘environmental’ discharges issues baseline studies have been completed, impacts have been monitored and measured, and finally, management measures have been implemented.


Her-1, Her-3 Level 3

An education program was developed for the ACT school curriculum which included sustainability themes such as environment, engineering, Indigenous and European heritage, sustainability and water supply.

Partnerships with key stakeholders (RAOs, ACT Heritage Unit, ACTEW Water, BWA, Parks, Conservation and Services) were formed through the project . The Cotter Dam Discovery Trail was developed to provide on-going local promotion and enhancement of project related European and Aboriginal heritage values.

Representative Aboriginal Organisations (RAOs) participated in the field survey program and salvage field work.