Walpole new source

Walpole’s water currently comes from Butlers Dam, supplemented during peak periods by water carting from Denmark or Albany. The town has also previously been supplied from the Walpole River Weir, Chatley Road Dam, and two shallow bores on Swann Road, however these sources proved unreliable.

Butler’s Dam is spring fed and has a small capacity of approximately 3,300 kilolitres (approximately 1.3 Olympic swimming pools). While it generally has a reliable inflow of water each day most of the year, spring flows decrease in late summer. Low flows coincide with the periods of peak demand in Walpole, driven in part by seasonal tourism.

In some peak periods, Butler’s Dam can only supply approximately 200 kilolitres per day, whereas Walpole demand is predicted to reach as high as 400 kilolitres per day by 2050.

Supply from Butlers Dam is not enough to support Walpole into the future.

Butlers Dam is also located in an agricultural area, which means a high level of water treatment is required.

Many factors are considered when preferencing water sources, including:

• water quality
• drying climate patterns and rainfall / streamflow data
• environmental considerations including impact of drawing water on local ecosystems and construction impacts on existing flora and fauna habitats
• heritage and Native Title rights
• general community feedback
• impact on private landowners
• water treatment requirements
• amount of water we expect to draw from the source and;
• cost of supplying water to our customers including building the required infrastructure.

Based on a preliminary consideration of these factors, Water Corporation is now planning a trial of three new bores, located near Swann Road, to supply Walpole with groundwater. New, deep groundwater for Walpole is likely to be quicker to implement, be more reliable than surface water in a drying climate and have preferable water quality.

Before a new water source can be implemented, we are required to collect extensive environmental and heritage information, and conduct investigations and trials.

Walpole River Weir
The river has not been used as a source since 2010. Abstraction from the weir ceased due to low water levels in summer and deteriorating water quality.

Chatley Road Dam
This dam was used as a source between 2015 and 2019. This was originally a farm dam and was on a property within the catchment of the proposed Samuels Brook Dam. Water Corporation had purchased the property so that nutrients from grazing cattle would not have contaminated Samuels Brook Dam, if it had been constructed. Water from the dam was fresh, but concerns about the structural integrity of the dam led to a decision to decommission the dam.

Swann Road bores
Two shallow bores were drilled near Swann Rd and used intermittently between 2012 and 2020. Those bores drew from a shallow aquifer. They did not produce a reliable volume of water and there were concerns about the environmental impact on the shallow aquifer.

The bores we would use for a groundwater trial have already been constructed as test bores, near Swann Rd, as part of previous investigations into potential new sources for Walpole. However, to use these bores in a trial to supply Walpole, we need to undertake a number of investigations, such as environmental surveys. Those investigations, and the trial itself, will allow us to determine how much water can be drawn sustainably as Western Australia’s climate continues to dry.

The investigations will take place over the coming months and include surveys and monitoring to capture accurate environmental data and heritage information to support our planning and approvals.

We always try to build new infrastructure such as pipelines in road reserves or Crown land to minimise impact to private landowners and the environment. Survey areas typically extend further than the actual footprint of any infrastructure so results can be put into context.

We will engage with Department of Water Environment Regulation, other government agencies, stakeholders and the community before making decisions regarding the planned borefield trial or any other sources for Walpole.