Today marks the start of construction on the Cotter Dam extension on the western outskirts of Canberra. Enlarging the Cotter Dam has long been contemplated as an option for increasing water supply to the ACT and surrounding region.
Constructed in 1912 and enlarged to 4 gigalitres (GL) in 1951, the Cotter Dam provided all Canberra’s water until 1961, when Bendora Dam was constructed.
The three year project will increase the dam’s capacity from 4 gigalitres of water to 78 gigalitres increasing total storage capacity for the ACT region by 35 per cent.. One reason for selecting the larger dam over a smaller one relates to the ability to get more water for less cost. Also, there is a concern that a rock ledge at the back of the dam would make it difficult for fish to pass through at certain times. The advantage of the larger dam is that this would flood the rock ledge and accommodate the passage for the fish, including the endangered Macquarie perch.
The cost estimate is approximately $363 million for the dam and associated works, which includes construction, commissioning and alliance costs of $299 million, environmental and recreation mitigation costs amounting to $13 million and owner’s costs to ACTEW for project inception, planning, design, approvals and costs from now until completion of $51 million. It is expected to take two years to build.
“This development is the biggest building project in the ACT since the construction of the new Parliament House and is an extremely important project for the ACT and surrounding community,” Senator Lundy said, “It will help ensure we have adequate and safe drinking water supplies even if climate change leads to longer and more severe droughts.”
Full information about the project is available at the ACTEW website – http://www.actew.com.au/. Many thanks to ACTEW for their permission in using their diagrams in this post and also in the short video about the launch below. Photos and other video footage were taken today by Pia, Annika and Eliza from my office. Please see the original ACTEW video for full details and more information.
Additional information:
Water Storage Levels
Current Storage Levels
Current Dam Storage Levels
Combined Storage Levels over 12 Months
Combined Storage Levels over 12 Months
Combined Storage Levels over 5 Years
Combined Storage Levels over 5 Years
Please note that for the above graph:
- Cotter Dam, the smallest of our four dams, which had not been able to be used since 1968, was reinstated and began being used in Jan 05. This added almost 4 GL of extra storage capacity to the regions water supply.
- Bathymetry surveys were conducted at Corin and Bendora Dams in November 2005 to re-calculate the dams actual storage capacities. This resulted in an updated change to our total storage capacity from 215.4 GL to 211.6 GL.
- Bathymetry surveys were conducted at Googong and Cotter Dams in October 2006 to re-calculate the dams actual storage capacities. This resulted in an updated change to our total storage capacity from 211.6 GL to 207.4 GL.
An artist’s impression of what the enlarged Cotter Dam will look like when completed. (ACTEW Corporation )
Artists impression of the expanded Cotter Dam
The original ACTEW video, which has loads of useful information is below.
