Watertable Aquifer

The watertable is the level where the water pressure in an aquifer equals the air or atmospheric pressure. The aquifer that contains the watertable is highly variable across the Greater Melbourne Area. It is made up of unconsolidated material such as sand and gravel, as well as fractured basalt, sandstone, shale and some granitic material. It includes Quaternary, Upper and Lower Tertiary age sediments and bedrock.

Available maps include:

Watertable Depth (PDF~2.6mb)Watertable Elevation (PDF~6.0mb)Watertable Salinity (PDF~2.0mb)Watertable Yield (PDF~1.9mb)Watertable Managed Aquifer Recharge (MAR) Storage Potential (PDF~1.9mb)

Upper Tertiary Aquifer

The Upper Tertiary Aquifer was formed 5 million years ago in the Palaeocene geological epoch. It is a varied sequence of sedimentary materials, predominantly comprising clay, silt, sand and gravel. Major geological units within the Upper Tertiary Aquifer include the Moorabool Viaduct Formation (Otway Basin and west of Port Phillip Basin), the Brighton Group Formation (Port Phillip Basin and Nepean Peninsula), and the Baxter Formation (Western Port Basin).

Available maps include:

Upper Tertiary Aquifer Potentiometric Surface (PDF~4.3mb)Upper Tertiary Aquifer Elevation (PDF~5.2mb)Upper Tertiary Aquifer Salinity (PDF~3.1mb)Upper Tertiary Aquifer Yield (PDF~1.4mb)Upper Tertiary Aquifer Managed Aquifer Recharge (MAR) Storage Potential (PDF~1.7mb)

Middle Tertiary Aquifer

The Middle Tertiary Aquifer was formed between 23 and 5 million years ago in the Oligocene to Miocene geological epochs. It is comprised of clay, silt, sand, marl and limestone and acts mainly as an aquitard (a layer of rock or soil that does not easily allow water to move through it). Notable geological formations within the aquifer include the Gellibrand Marl and Jan Juc Formation in the Otway Basin, the Fyansford Formation and Batesford Limestone in the Port Phillip Basin, and the Sherwood Formation in the Western Port Basin.

Available maps include:

Middle Tertiary Aquifer Elevation (PDF~2.1mb)

Lower Tertiary Aquifer

The Lower Tertiary Aquifer was formed 65.5 to 23 million years ago in the Palaeocene to Oligocene geological epochs from sedimentary and volcanic materials. It sits on top of Bedrock Aquifer and is made mainly of clay, silt, sand, gravel, coal and basalt. Major geological formations within the Lower Tertiary Aquifer include the Dilwyn and Eastern View Formations in the Otway Basin, the Werribee Formation and Older Volcanics in the Port Phillip Basin (including the Nepean Peninsula), and the Childers Formation and Older Volcanics in the Western Port Basin.

Available layers include:

Lower Tertiary Aquifer Potentiometric Surface (PDF~3.6mb)Lower Tertiary Aquifer Elevation (PDF~3.5mb)Lower Tertiary Aquifer Salinity (PDF~2.3mb)Lower Tertiary Aquifer Yield (PDF~1.8mb)Lower Tertiary Aquifer Managed Aquifer Recharge (MAR) Storage Potential (PDF~1.6mb)

Bedrock Aquifer

The Bedrock Aquifer is the hard rock that forms the hills and mountains in and around Melbourne and which underlies the younger aquifers. It is made mainly of folded and fractured sandstone and shale with some granite.

Available maps include:

Bedrock Aquifer Elevation (PDF~4.0mb)

Groundwater Trends and Changes

The final page of the Atlas displays a series of hydrographs from representative monitoring bores that highlight the groundwater trends and changes in Victoria.

Available maps include:

Examples of Groundwater Trends and Changes (PDF~1.9mb)