8 September - Emergency Response Team callout
On 8 September 2022, the EPA's Emergency Response Team received a report of a white discharge visible in Third Creek at Melory Crescent, Magill. Photographic evidence was provided by the resident, taken at approximately 4:25 PM.
An EPA staff member arrived at the site at approximately 4:55 PM and all traces of the white substance had dissipated both upstream and downstream (please see photo gallery). The was very high rainfall throughout the catchment at the time, the flows were very high in speed and volume, and as a result the substance would have been heavily diluted and pushed downstream very quickly. No other downstream witnesses reported a white plume to the EPA at the time. Sediment loads within the creek were observed at all locations, which were consistent with the water coming in from the surrounding catchment under high volume heavy rainfall.
Turbidity within Third Creek was impacted by sediment from a number of sources, which is common when there is high rainfall. On this occasion however, the EPA investigated Hanson’s site operation and real time monitoring data and determined the white discharge had not originated from White Rock Quarry. However, EPA acknowledges Hanson still has a contribution to the sediment discharge to the Creek (please refer to 'surface water management' section below).
Line marking being undertaken and having washed away along the route was also ruled out as a source after further investigation. Due to the short-term nature of the discharge, the EPA considers that an isolated event such as paint or another substance inadvertently or deliberately being discharged to the Creek was the cause of the pollution, however is not able to confirm the source on this occasion.
We would however, like to strongly encourage residents to please keep reporting events to enable us to investigate, as whilst this incident was not able to be attributed to an offender there are many occasions when it can be and we value the community's support of our regulatory efforts.