What is groundwater?

Groundwater is water found below the surface. It is typically contained in aquifers, which are porous materials such as gravel, sand and fractured rock that hold water in the gaps, like a sponge. 

Rainfall and run-off enters aquifers at recharge areas, flows underground, and eventually discharges to creeks, rivers, lakes or the ocean. Some aquifers discharge at natural springs. 

Groundwater can be harvested via bores, i.e. pipes drilled into the ground to tap into the aquifers. The quality of groundwater sources varies widely. 

Some supplies are so pure they are bottled at the source and sold as spring water or mineral water. Others are so high in dissolved salts they are unsuitable for drinking. 

Groundwater may be tens, hundreds or even thousands of years old. Many cities and countries around the world depend on groundwater. Waterways and ecosystems also rely on it.

Do conditions apply in operating the groundwater?

The borefield is operated under a licence issued by Southern Rural Water, which is responsible for licensing and monitoring groundwater extraction in southern Victoria on behalf of the Water Minister. 

The licence sets out conditions so that groundwater use is carefully monitored and managed. The licence covers extraction volumes and monitoring requirements. The maximum extractable volume in any one year is 20,000 million litres.

The maximum extractable volume over any 10-year period is 80,000 million litres and 400,000 million litres over a 100-year period. As part of the Barwon Downs licence, Barwon Water monitors: 

- groundwater levels and pressures
- groundwater quality (including salinity)
- groundwater pumping rates
- subsidence
- flows in Boundary Creek and the Barwon River
- vegetation health. 
Barwon Water conducts ongoing monitoring in accordance with the licence. This includes regular groundwater level monitoring, flora studies every five years and measuring volumes of water pumped from the Barwon Downs aquifer. 
Barwon Water’s current licence to operate the Barwon Downs borefield was issued in 2004 and is due for renewal in June, 2019.

What is groundwater monitoring?

Groundwater is monitored via dedicated observation bores. Monitoring has continued since the borefield began operating more than 30 years ago.

Groundwater monitoring aims to improve the understanding of groundwater behaviour, the connections with surface water, and any changes to groundwater levels due to pumping or climate.

As part of the upgraded monitoring program, we have installed 37 new monitoring bores, repaired 3 old bores, and increased groundwater quality sampling.

What is terrestrial ecology?

Terrestrial ecology monitoring aims to better understand the relationship between groundwater, groundwater pumping and surface ecosystems.

We undertakes periodic surveys of plant life at sites where vegetation may dependent on groundwater.

The monitoring program has been expanded to 13 sites including 11 new ones incorporating stream banks, wetlands, swampy scrub and woodland.

What are acid sulfate soils?

Acid sulfate soils are those that contain iron sulfide minerals (notably pyrite, or “fool’s gold”) and occur naturally under waterlogged conditions.

Undisturbed and below the water table, acid sulphate soils pose no risk. However if the soils are drained or exposed to air by the lowering of the water table, the sulfides react with oxygen to form sulfuric acid. This can release iron, aluminium and other metals within the soil, and has the potential to adversely affect the local aquatic and terrestrial ecosystems.

Although we are not required to monitor acid sulphate soils as part of our groundwater licence, we are monitoring four sites as part of the upgraded program.

What is aquatic ecology?

We release flows into Boundary Creek to comply with our current licence and maintain healthy habitats for aquatic life.

An aquatic ecology team will identify, examine and monitor the flora and fauna in suitable habitats on Boundary Creek. We will measure and monitor flow levels in the creek.

Data from the upgraded monitoring program will help determine whether the volume and timing of the releases are appropriate, and whether improvements could be made to better maintain healthy aquatic ecosystems.

What is a stream flow?

We monitor passing flows in Boundary Creek and the Barwon River as part of our current licence.

Stream flow monitoring aims to better understand the connection between surface water and ground water, including groundwater recharge areas.

The new monitoring program will include upgraded stream gauges and dataloggers at selected sites on Boundary Creek and the Barwon River.