Anglesea River
Every year for 46 years ALCOA pumped 3.5 billion litres of water from the aquifer under the Anglesea River catchment. This was clearly unsustainable – the aquifer water table dropped from near the catchment surface to 70 metres below sea level. The level was still falling when ALCOA closed down its controversial open cut mine and power station in 2015.
Now, simply to speed up the filling of the open cut mine void it has left behind, ALCOA wants to resume exploiting the now-recovering aquifer. It claims its motivation is to hand over the rehabilitated ‘asset’ to the community as soon as possible. But the permanently acidic, lifeless mine void is not an asset, and won't be handed over to the Anglesea community any time soon. The state government will be the custodian, and it has no published plans for the site after ALCOA's rehabilitation responsibilities are fulfilled. It looks like it's up to the Anglesea community to ensure it's not a fenced off ‘no go’ zone for decades more.
What happened?
The relentless exploitation of groundwater over almost half a century created two disastrous impacts on the Anglesea River ecosystem:
Flows from the creeks feeding the Anglesea River estuary dried up as the hydrating effect from the now-disconnected aquifer disappeared. The creeks used to flow into the estuary over 200 days per year. Now they flow around 20 days per year, with no flows recorded for years on end.
When the creeks do flow, they deliver toxically acidic water into the estuary. The soils in sections of the swampland are prone to generating sulphuric acid when they dry out and are exposed to oxygen. However, the fish kills which the Anglesea River is becoming infamous for, only commenced in 2000. For three years from 2019 to 2022 there were no fish at all in the river. Something has changed. Friends of Anglesea River are convinced that ALCOA is responsible for the change through its groundwater pumping.
Will it recover?
No good can come to the Anglesea River until a permanent lock is put on groundwater pumping. Every year the aquifer is interfered with is another year's delay in the recovery of the system – it's that simple. Other measures are needed, but unless we take this first essential first step towards remediation, they will be futile.
The good news is that the aquifer will recover if left alone. The water table will rise and once again help contribute to creek flows as it had done for centuries prior to ALCOA's intervention. Already, with no groundwater extraction for most of the past 10 years, recovery has been better than anticipated.
The mine pit will fill over time without pumped groundwater. It's taking more than its 'fair share' of water already. Before it was an ugly blot on the landscape, this area contributed to flows. Now it takes water from the system. The pit is filling in part with groundwater, in part with rainfall. The groundwater would otherwise contribute to the recovery of the damaged aquifer. The rainwater which drains into the pit would otherwise be draining into the estuary, contributing to the health of the catchment.
ALCOA will be long gone before any unintended consequences, such as cross-contamination of the aquifer with acidic water, or ingress from seawater begin to surface.