Significant water events
Significant flooding occurred within the Canberra region in December 2011, which seriously affected the community around Queanbeyan. Around 100 houses and businesses were flooded when over 100 mm of rain fell in twelve hours, creating flood events similar to those in 1974 and 1976, with peak river heights of around 8.4 m.
For the 2010–11 year most of the Canberra region saw very much above average rainfall; this is reflected in Figures W1, W2 and W3, which each have flow rates well above the long-term average. Figure W1 shows a peak flow in December, which corresponds to the flooding events which were recorded in the region.
Figure W1. Monthly flow of the Molonglo River at flow gauging station 410705
There are three key water storages located on the Cotter River, the Corin, Bendora and Cotter Reservoir supply urban water for the Canberra region. Figure W2 shows flows down the Cotter River at gauge 410730 located upstream of the Corin Reservoir. These flows enter the Corin Reservoir where water released or spilled will flow downstream to the Bendora Reservoir and eventually to the Cotter Reservoir.
Figure W2. Monthly flow of the Cotter River at flow gauging station 410730
The Queanbeyan is a tributary of the Murrumbidgee River, significant in the context of the Canberra region as the Googong Reservoir is located on the river, southeast of Queanbeyan. High inflows into the Googong catchment saw increased streamflows and runoff into storage in the 2010–11 year.
Figure W3. Monthly flow of the Queanbeyan River at flow gauging station 410781
Major water initiatives
On 17 May 2011 the Environment and Sustainable Development Directorate (ESDD) was formed. This was part of widespread structural reform in the ACT public service to strengthen capacity. ESDD delivers services and policy in the areas of climate change, waste, heritage, planning policy (including transport planning), and development, natural resource management, energy and water (ESDD 2011).
Following the Water Security Review in 2007, the ACT Government announced a range of new water supply projects, which ACTEW continued to implement throughout the 2010–11 year.
- enlarging Cotter Reservoir to increase the capacity to 78,000 ML. Construction of this project commenced late 2009 and was expected to be completed in 2012 but significant rain events and flooding in 2012 have delayed construction
- Murrumbidgee to Googong water transfer pipeline, which will allow the transfer of water from the Murrumbidgee River to Burra Creek, where it will flow into Googong Reservoir. Planning for this transfer continued during the 2010–11 year and construction commenced in early 2011 and is anticipated to take 18 months to complete
- ACTEW have purchased 4.145 GL of high security and 12.5 GL of low security NSW water entitlements to be utilised under the Tantangara transfer, this is expected to be available for use upon the completion of the Googong transfer pipeline
- design of a demonstration water purification plant to treat wastewater to produce high-quality drinking water. The design of this project is now complete; but construction was deferred subject to the successful implementation of the three preceding projects (ACTEW 2010).
During the 2010–11 year, the Draft Water Sharing Plan for the NSW Murray–Darling Basin Fractured Rock Groundwater Sources was progressed. The draft plan was on public exhibition from 6 December 2010 to 31 January 2011. All submissions were considered in finalising the statutory plan, which will be in place for 10 years.
On 8 October 2010, Murray–Darling Basin Authority published the Guide to the Proposed Basin Plan. Volume 1 of this suite of publications outlined the basis of the draft Basin Plan; the technical detail was set out in parts 1, 2 and 3 of Volume 2 of the guide. Preparation of a Draft Basin Plan continued for release later in 2011.
One of the key elements of the Guide to the Proposed Basin Plan is the setting of new limits – sustainable diversion limits, or SDLs – on the amount of water used in the Basin. Sustainable diversion limits will be enforced through state water resource plans.