Groundwater level monitoring and triggers
As part of our comprehensive monitoring and assessment program, we have 42 observation bores that monitor groundwater levels across the Anglesea catchment. These observation bores are located at different depths to monitor groundwater levels in different geological formations – in the Perched Water Table (PWT), Upper Eastern View Formation (UEVF) and Lower Eastern View Formation (LEVF).
View the Anglesea borefield cross section to see the different formations.
Groundwater levels are continuously monitored to ensure that operation of the Anglesea borefield does not cause significant drawdown, particularly in the Anglesea Swamp. If groundwater levels remain within the likely range of natural variation, then we can be confident that operation of the Anglesea borefield is not threatening groundwater dependent ecosystems.
Of the 42 observation bores, there are two key bores that are critical to ensuring groundwater levels can continue to support groundwater dependent ecosystems. These bores measure groundwater levels in the PWT (P8) and in the UEVF (P19).
It is the combination of groundwater levels in both of these bores that is important. If groundwater levels in both bores fall below a certain threshold level, then action must be taken to prevent any potential damage to groundwater dependent ecosystems.
The threshold level (also known as a “trigger”) is determined by comparison to a control bore, to account for climatic influences on groundwater levels. The control bore (P17) is located in the Salt Creek swampland outside the predicted area of influence of any operation of the Anglesea borefield. This means the control bore provides a useful comparison of the natural variation in groundwater levels due to seasonal conditions.
We will report monthly on status against the threshold level for the two key bores. The first update will be provided in December 2019.