Information Sheet- Brunswick Dam
Background
The Brunswick River runs past the town of Brunswick Junction in the south west of Western Australia and flows into the Leschenault Inlet near Bunbury. The short term average streamflows (last 30 years) are in excess of 50 gigalitres per annum.
Beela Dam, a small dam on the Brunswick River, can provide drinking water supply to Brunswick Junction. However, a more secure groundwater source now supplies Brunswick Junction and there is currently no abstraction from Brunswick River for public drinking water supply. There is another dam in the upper reaches of the catchment which supplies water to the Worsley alumina refinery.
The water quality of this river is considered to be at a high risk of contamination even though the salinity levels are acceptable for drinking water. Various land uses within the catchment contribute to the risks: the refinery, other mining leases, freehold land which is used for cattle grazing and other agricultural practices, and recreational activities within the catchment area.
Current Situation
The Water Corporation has previously identified the Brunswick River as a potential water source for Perth. Planning has been undertaken and a number of development options considered.
A new dam may have the potential to supply up to 30 gigalitres per year. While it is a highly prospective water source, it is anticipated that up to five or more years will be required to complete regulatory approval processes. The environmental and social impacts are important and would be the primary areas of focus.
The Future
Several source development options have been considered:
- A small dam on the lower reaches of the river, pumping back to the South Dandalup dam in the IWSS water grid - estimated yield up to 28 gigalitres a year;
- A small dam on the lower reaches of the river, pumping to a new large dam in the upper reaches of the Brunswick River or to an off stream storage located on a tributary - estimated yield up to 32 gigalitres a year; and
- A major dam on the Brunswick river – estimated yield up to 34 gigalitres a year.
All options need further assessment to consider the requirements for connecting into the IWSS water grid. Full water treatment will be required.
Sustainability considerations – addressed in planning
Economic | Social | Environmental |
Relocation of roads and rail due to inundation in the catchment | Recreational activities in the catchment would need to be curtailed | Inundation of the river valley that includes State forest and some private land |
Possible impacts on the alumina refinery upstream which may need compensation | Impacts on Aboriginal and European heritage – impact on coalfields railway and historic farm buildings by water body | Impact on rare and endangered flora, loss of riparian and forest environments and impacts on downstream flows and ecosystems |
Costs are more expensive than current IWSS water sources, but less than desalination costs | Impacts on privately owned land | Dam will restrict movement of aquatic fauna |
Potential source yield
Source yields in the order of 20 to 34 gigalitres a year may be available, dependent on the option. This is enough water to supply more than 100,000 new homes.
Potential cost
The unit cost of the options is estimated to be in the order of $1 to $2 a kilolitre.
Key
13.jpg)
Potential source yield (in 50 year planning horizon)14.jpg)
Potential cost (2007 $)