One of the key outcomes of wastewater treatment is ensuring the receiving environment is protected. But how do you monitor a treated water discharge into a very large, high energy ocean environment? How can we measure the health of the local marine environment from year to year?
For the Eastern Treatment Plant, which discharges at the South Eastern Outfall, the answer is intertidal habitat monitoring. The intertidal zone is an area of rocky reef that is covered by water at high tide but exposed during low tide. We know from studies carried out in 1975, prior to the opening of the outfall, that the dominant seaweed along this coastline should be Hormosira banksii – commonly known as Neptune’s Necklace. Other species such as Ulva, Corallina and Capreolia are also present here. But over time, we began to notice that Ulva, Capreolia and Corallina were becoming more dominant in the area around the outfall.
With the 2012 tertiary upgrade at the Eastern Treatment Plant, an improved quality of effluent is now being discharged. Regular monitoring of the region around the outfall is also showing a significant recovery in the population of Hormosira banksii.
A key priority for Melbourne Water is supporting a healthy ecosystem. This data demonstrates how, as a result of the treatment upgrades, and via continued monitoring of the region near the outfall, this ecosystem is returning to its natural state.