SHOCK FINDINGS: Latest tests from Bexhill Quarry waterhole

Southern Cross University laboratory director Graham Lancaster checks the Bexhill Quarry water Ph to see whether the acidity levels were dangerous to humans.
Southern Cross University laboratory director Graham Lancaster checks the Bexhill Quarry water Ph to see whether the acidity levels were dangerous to humans. Marc Stapelberg

A WATER testing expert says he would "not have a problem" taking a dip in the Bexhill Quarry after new samples revealed it was very close to meeting Australian and New Zealand recreational water guidelines.

The enticing turquoise blue lake has long been a popular place for swimmers but until recently was considered potentially dangerous due to its acidity levels.

But the latest testing from the Environmental Analysis Laboratory at Southern Cross University has revealed the waterhole is only marginally acidic - and certainly not dangerously so.

Lab director Graham Lancaster said while the new tests returned a pH reading of 4.1, more acidic than the 5.0 to 9.0 recommended by the Australian New Zealand guidelines, the actual quantity of acid was negligible.

"When we actually test the quantity of acidity we're only getting 14mg per litre," he said.

"I was expecting this to be at least 50 to 80mg per litre... so it is moderately low."

By way of comparison, testing of the water in Lake Ainsworth at Lennox Head returned a reading of 7mg of acidity per litre, while the Wilsons River at Lismore returned 3mg per litre.

To put this is perspective, Mr Lancaster pointed out that vinegar or coca-cola would be in the "hundreds" of milligrams per litre.

He also explained the water was "pristine" so had little "buffering capacity". As a result, the pH level tended to be lower than it otherwise would be.

"I can't see any major issue in swimming in that water," he said.

"It probably wouldn't be hard to treat it with a very small amount of lime, or some other buffering compound, to bring that pH just up a little bit, (but) you wouldn't want to change the chemistry."

Another benefit of the water is that there is no bacteria or algae at all, unlike other swimming spots like Lake Ainsworth which has recently been suspected of causing a number of swimmers to fall ill.

"It's fresher water, there's no algae, and there is no nutrients," Mr Lancaster said.

Metals in the water include aluminium, iron, manganese, and zinc, some of which give it a characteristic blue tinge.

Mr Lancaster said these were considered non-toxic to swim in.

The swimming spot is attracting more and more people from further afield due to its iconic blue water, with several swimmers yesterday saying they had seen it on Instagram.

Zoe English and friend Sophie Tunsted, of Lismore, said they had been coming to the spot for several years.

"I love the colour of the water," Zoe said.

"Now that I know it's okay to swim in I feel a lot better."

Laura Duncan and boyfriend Charlie Brennan had come from the Gold Coast for a dip.

"We've been a couple of times," Laura said. "I spoke to one of my friends who came here and got the address from her."

"I think everyone just loves how blue it is."

Chris Tucker, of Lismore, said he had been swimming at the quarry "since I was a kid and if it was going to affect me it would have done it years ago."

"Look how big it is, you could have a thousand people here," he said.


Bexhill Quarry

Ph 4.1

Acidity -mg/litre 13

Faecal coliforms - cfu/100ml <10

Cyanobacteria (blue-green algae) - cells per ml 180

Lake Ainsworth

Ph 5.8

Acidity -mg/litre 7

Faecal coliforms - cfu/100ml 60

Cyanobacteria (blue-green algae) - cells per ml 1140

Wilson River, Lismore

Ph 7.65

Acidity -mg/litre 3

Faecal coliforms - cfu/100ml 30

Cyanobacteria (blue-green algae) - cells per ml 360

Topics:  bexhill quarry graham lancaster northern rivers environment scu water quality

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