Water quality

Gladstone Area Water Board (GAWB) supplies bulk water in two forms – raw water and drinking water. Raw water is untreated water, delivered to customers directly from Lake Awoonga. Raw water is mostly used by local industries in their processes and is unsuitable for drinking – it accounts for approximately 77% of water supplied by GAWB.

The remaining 23% of water supplied by GAWB is treated to drinking water standards and delivered to bulk drinking water customers, including the Gladstone Regional Council, who then reticulates the water to domestic customers to use in homes and commercial premises.

Source water

GAWB owns and operates Awoonga Dam, our distribution network and supporting infrastructure, including water treatment and water quality. The source of our water is Lake Awoonga, a man-made lake designed to capture surface run-off from within the Boyne River Catchment. The Boyne River Catchment covers approximately 2, 230km²  and is bounded by the Many Peaks range to the East, the Dawes Range to the South, the Calliope Range to the South-West and the Boyne Range to the West.

Many factors influence the quality of water in Lake Awoonga, especially climate, hydrology, geology and land use. The Catchment area is located in the dry sub-tropics, with typically mild, dry winters and warm, wet summers. Approximately 57% of the Lake Awoonga catchment area is forested with remnant vegetation consistent with Brigalow Belt Bioregion Regional Ecosystems (9%) and Southeast Queensland Bioregion Regional Ecosystems (48%). Of the remainder, 2% is regrowth forest, 39% is cleared land and 2% is water storage. Hydrologically, the Boyne system is characterised by highly variable flow and sediment regimes, as different morphological features have developed in response to topographical features and dominant flows.

The geology of the catchment consists of a range of interbedded sedimentary and volcanic formations. Limestone and mudstone are also present.

The Boyne Valley is generally zoned rural with limited commercial operations. Land use within the catchment remains primarily agricultural, with light to medium cattle grazing, some cropping and forestry activities. There are several active mineral exploration leases in the upper catchment and one operating limestone quarry.

Drinking water quality

As a registered water service provider, GAWB must ensure our water supply is managed in accordance with the water quality standards outlined in the National Health and Medical Research Council’s Australian Drinking Water Guidelines 2011 and aligned with GAWB’s Drinking Water Quality Management Plan, and any other relevant regulatory requirements.

To ensure we remain compliant with these guidelines, GAWB runs robust water quality testing for number of chemicals and pathogens including E.coli, total trihalomethans (chlorine by-products), aluminum, arsenic, barium, cadmium, chromium, copper, lead, mercury, nickel, selenium and zinc.

Monitoring for other metals and chemicals, such as pesticides, is undertaken on an event basis at limits of detection consistent with the drinking water guidelines.

Each year, we publish the Drinking Water Service Annual Report. To see previous years’ reports, please visit ‘publications’ under the ‘knowledge centre’ tab. 

PFAS

PFAS are per- and polyfluoroalkyl substances, a group of over 4000 chemicals. While understanding of the human health effects of PFAS exposure is still developing, many countries including Australia, are working to phase out or have already discontinued the use of certain PFAS.

Read more about PFAS from the Australian Government PFAS Taskforce. 

The current health-based guideline values for PFAS in the Australian Drinking Water Guidelines are:

• less than 0.07 micrograms per litre for the sum of PFOS and PFHxS (combined)
• less than 0.56 micrograms per litre for PFOA.

Under those same guidelines from the National Health and Medical Research Council, GAWB is not legally required to undertake regular PFAS testing.

However, as part of our catchment monitoring program, GAWB proactively conducts annual sampling for PFAS at ten sites across the Lake Awoonga catchment, along with five sites upstream and two sites downstream of Awoonga.

The samples confirm GAWB meets Australian Drinking Water Guidelines, with no detectable level of PFAS.

If you would like to learn more about PFAS and the Australian Drinking Water Guidelines, the Water Services Association of Australia has produced a helpful factsheet.