SOS Water

Reporter: Mark Gibson

It's the sort of health warning that would make international headlines. 'Deadly Poisons Found in the Water' and it's happening in suburban Perth.

Lake Gwelup is between the northern suburbs of Innaloo and Karrinyup and this is what the water looks like, close up. We know that the brownie, orange colour means there are high levels of iron, but there's so much more we don't know, which is why a Curtin University research team is digging deep into the ground.

Within minutes, they extract soil and water samples from up to eight metres below the lake and have a quick check for evidence of dangerous acidification.

There's a natural explanation for why this water has turned acidic. It's all to do with our drying climate. At the bottom of lakes is a sulphide mineral that normally wouldn't pose a problem, but if the sulphide becomes exposed to the air, it creates sulphuric acid. Over the past decade, as our rainfall dries up and the water table lowers, those sulphide minerals have become exposed to oxygen and turned into acid - a deadly acid that's killing plants and animals.

Associate Professor Ron Watkins heads the research team. In a laboratory at Curtin University, the samples from Lake Gwelup are analysed.

Here, they're testing the PH levels. Most living things survive in water with a PH of 7.

The lower the PH, the bigger the problem. At Lake Gwelup...

"We are talking about creating ground water with a PH as low as maybe 2.8".

Stirling resident Steve Janjetac knew something was wrong with the groundwater, when his vegetables started dying.

Steve and wife Stanka sent soil samples to Melbourne for independent testing. The results were alarming.

To give you some idea about arsenic, safe drinking water should have no more than 7 micrograms of arsenic per litre. Official guidelines say recreational water like lakes should have no more than 100 micrograms per litre, but testing at Spoonbill Lake in Stirling found 900 micrograms of arsenic per litre of water. That's 128 times the safe drinking level.

The wetlands in Stirling and Gwelup are so putrid they carry health warnings.

The Department of Environment and Conservation has identified areas at risk from acidification.

Across Perth and the south-west, our drying climate means sulphide minerals are now dangerously close to the surface.

The Department's Stephen Wong says its vital information for developers.

" Identifying these areas up front will assist the building or development industries to identify the risk and address those risks and manage those risks appropriately without creating any environmental or public health risk" says Mr Wong.

The experts agree if you're going to use bore water make sure you get it regularly tested. The problem of acid water will be with us for decades to come.

For more info contact...

Department of Environment and Conservation