Con­cerns over water qual­ity


Comment News (Gosnells) - - OPINION -

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 it 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 run-off 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 sum­mer and the Open Water Swim­ming State Cham­pion ships last Novem­ber.

Sport­ing groups in­clud­ing row­ing, kayak­ing, dragon boat­ing and time tri­als (cy­cling) also use the venue.

Cus­tomer sat­is­fac­tion in the venue for the 2015-16 fi­nan­cial year was 90 per cent.

Cham­pion Lakes... salinity is three times higher than salt-water pools.

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