WATER at Champion Lakes Regatta Centre is so salty that permission is being sought to drill four new bores to reduce salinity.
Lake water salinity is about 11,000 parts per million – more than threes times higher than a traditional salt-water pool.
If the plan fails to improve the water quality, desalination may be considered.
Managing body VenuesWest has applied for a Department of Water licence to draw 190,000KL – or 76 Olympic-sized swimming pools – of fresher water from a superficial aquifer each year.
Department of Water Swan Avon Region manager Don Cummins said the department had yet to make a decision on the application because it was waiting for hydrogeological modelling.
“Seepage and overflow of water from Champion Lakes have potential to impact nearby vegetation and the local groundwater,” Mr Cummins said.
“This risk is currently managed through the environmental operating requirements for the lake.”
While the lake’s salinity is not considered to be a health issue, it can kill fringing plants which affects the stability of the shore line.
The increase in salinity has been attributed to evaporation, according to VenuesWest chief executive David Etherton.
The lake was filled from the more brackish Yarragadee Aquifer and VenuesWest will reduce the rate at which is recharges the lake from this aquifer.
A planning document from 2002 shows the lake holds about 2.31GL (2.31 billion litres) and this same document raises the possibility of a saline plume under the pre-existing and seasonally filled Wright Lake. This lake was extended to create the regatta centre.
Four years ago, in April 2013, the State Government announced $1.5 million to improve water quality including salinity at the centre.
About $120,000 of the $1.5 million from the State Government was spent on expert advice, and $150,000 was used to build a water transfer pipeline in January 2015 that feeds and flushes the main nutrient swales.
These swales will also be refurbished every three years to ensure they filter runoff from the surrounding urban area properly.
The proposed new bores are expected to cost $460,000 over two years.
The aquifer the bores are dug into will also be tested frequently to ensure it is not affected by the lake, and microbial monitoring of the lake water will continue on a fortnightly rotation, Mr Etherton said.
“Should the measures identified not stabilise then reduce salinity levels, the balance of funds will be considered for desalination,” he said.
That funding announcement to address salinity followed several reports by the Comment News of frequent closures due to bacteria in the water from bird faeces.
VenuesWest told Comment News recently it had closed one small section of the lake to swimming in the past 12 months.
Trigger levels for closure had been considered too strict in the past.
It hopes to switch from guidelines by the Australian and NZ Environment and Conservation to more recent guidelines listed by the National Health and Medical Research Council.
VenuesWest’s water testing parameters are now with the Office of Environmental Protection Authority for its review.
The centre held six triathlons during in summer and the Open Water Swimming State Champion ships last November.
Sporting groups including rowing, kayaking, dragon boating and time trialling (cycling) also use the venue.
Customer satisfaction in the venue for the 2015/16 financial year was 90 per cent.