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Blue Mountains dam closed after elevated levels of PFAS chemicals found | Water

WaterNSW has temporarily closed a dam in the Blue Mountains after tests found elevated levels of PFAS chemicals in the untreated water.

The state water authority said it had disconnected the Medlow Dam from the region’s water supply as a precautionary measure while further investigations were conducted.

Medlow Dam does not supply raw water directly. Water flows through other dams in the network to the Cascade Water Treatment Plant, which then supplies treated drinking water to Blue Mountains communities.

Sydney Water confirmed that the water supplied to communities from the Cascade plant was safe for consumption and met Australian drinking water standards.

In a statement, WaterNSW said it had conducted targeted surveys in the Blue Mountains region of the upper catchment of Greater Sydney to ensure other authorities had up-to-date information on the presence of PFAS.

PFAS (per- and polyfluoroalkyl substances) are sometimes called “forever chemicals” because they are difficult to destroy.

There are about 12,000 PFAS, and strong evidence of health harm – including a link to cancer – exists primarily for two: PFOA and PFOS.

The International Agency for Research on Cancer classifies PFOS as possibly carcinogenic, but points out that there is “insufficient” evidence that it directly causes cancer.

A report by a health expert panel on PFAS submitted to the Australian government found “there is currently no evidence that the chemicals pose an increased overall cancer risk.” Research on PFHxS is ongoing, and the evidence of health effects is less comprehensive than for PFOA and PFOS.

Tests of untreated water at Medlow Dam found total PFOS and PFHxS levels of 0.09 micrograms per liter.

This is just above the limits for treated water – 0.07 micrograms per litre – under the Australian Drinking Water Guidelines. Once water from Medlow Dam is treated by the Cascade plant, PFOS and PFHxS levels in drinking water will remain well within safe limits, WaterNSW said.

“Preliminary results published on the WaterNSW website indicate that Medlow Dam is the only part of the Blue Mountains dam network delivering elevated levels,” the agency said in a statement.

“This dam does not supply raw water directly, but has been disconnected from the supply as a precautionary measure while further investigations are carried out.”

After the water leaves Medlow Dam, it flows through Greaves Dam and the Upper, Middle and Lower Cascade Dams before reaching the Cascade Filter Plant.

Tests showed that PFAS levels in the untreated water reaching the filter plant were within Australian drinking water guidelines.

Prof Stuart Khan, a water expert and head of the School of Civil Engineering at the University of Sydney, said in general terms that if contaminants are detected in the water, the relevant authorities will try to identify the source and initiate remediation measures if necessary.

“But at this point … the message that Sydney Water is trying to convey is that contamination (with PFAS) is at a safe level and there is no cause for concern,” he said.

Khan said he did not believe it was necessary to close the Medlow Dam and that the dam’s water supply would be needed again at some point.

“This sends the message that there is a problem, even though the problem is nowhere near as serious as it is portrayed in the media,” he said.

Khan expressed concern that some media reports “are causing great damage to public confidence in the water supply”. “They are creating fear where there should be none and there is a danger that they (regulators) will then get the priorities wrong.”

By Bronte

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