The New South Wales Environment Protection Authority (EPA) says the level of heavy metals discovered in the drinking water of residents near a gold mine is typical for Australia’s rainwater tanks.
Key points:
- Testing shows good water quality at homes near a gold mine being investigated for alleged dust pollution
- Tank sediment has returned high levels of lead
- The environmental watchdog describes heavy metals presence as “typical” for rainwater tanks
The EPA tested rainwater and sediment in the tanks and kitchen taps of people living near Cadia Valley Operations (CVO) at Orange.
It was prompted by the discovery of heavy metals in the blood and rainwater of some residents.
The EPA said it collected more than 280 samples from almost 100 properties within a 50 kilometres radius of the mine.
“There were exceedences to the health-based Australian Drinking Water Guidelines values for lead … and cadmium,” its report stated.
The EPA said 14 per cent of tanks and 2.7 per cent of kitchen taps contained high levels of lead, and 1.7 per cent of tanks contained cadmium.
It concluded that the levels of heavy metals were within the “typical concentrations” found within rainwater tanks in Australia.
The sampling was done between June and August after CVO was ordered by the EPA to reduce its dust emissions.
The mine is currently subject to legal proceedings in the NSW Land and Environment Court relating to alleged dust pollution.
The EPA’s report found that there was no significant relationship between the concentration of metals in the water and the proximity to CVO.
In a statement, a Cadia spokesperson said “the findings correlate with independent investigations carried out by Cadia and NSW Health, and show no discernible link to the site by distance, location or concentration”.
“The reports also confirm the tank water sampling results for both water and sediment are typical of results found across NSW and Australia,” they said.
Tank sludge
The analysis included sediment on the bottom of 52 tanks.
“In the EPA’s investigation, we measured lead levels in sediment up to 800,000 times the concentration measured in water collected from the tank tap,” its report said.
“Despite the elevated lead in sediment from this tank, the concentration of lead in water in the tank was below the Australian drinking water guideline.”
The watchdog’s report stated Australian and New Zealand guidelines for sediment quality were to protect aquatic ecosystems and livestock and were “not suitable” for the protection of human health.
But water scientist Ian Wright disagreed.
Dr Wright, who is an associate professor in environmental science at Western Sydney University, is also on an independent expert advisory panel, established by the EPA, to oversee its investigation into CVO.
He conducted his own suite of testing on 40 properties and said the majority of kitchen tap samples had good drinking water.
But he said his results showed sediment at the bottom of the tanks was peppered with heavy metals.
“A large number failed the Australian Drinking Water Guidelines for arsenic, chromium, lead, nickel and zinc,” Dr Wright said.
“The median level for lead is 93 micrograms per litre, the [Australian Drinking Water] guideline is 10, so it’s very close to 10 times higher.”
Health warning
Dr Wright said the EPA’s reliance on national guidelines for sediment dismissed the risk that it posed, particularly as drought conditions spread across regional NSW and tank supplies started to dwindle.
He said the EPA’s advice to residents, to regularly clean water tanks and flush pipes, was inadequate.
“That sediment can be easily disturbed and can enter the household supply … and that contaminated sediment is really only a few centimetres from the outlet of their tank,” he said.
“Some people know it’s really important to clean out your gutters, to trim branches so birds don’t roost over your house because your roof is your water catchment.
“But if [the presence of heavy metals in sediment] is typical, there should be statewide alert to this and a statewide campaign about the issue.”
In a statement, an EPA spokesperson said it was carrying out work to try to identify the potential source of metals that have been found in sediment and soils.
It has asked Cadia to resubmit its air quality impact assessment because it “has identified a number of issues” with the document and wants the mine to review its modelling.
A spokesperson for Newcrest, which owns the mine, said it stood by the accuracy of the air quality assessment.
Posted , updated
