What is groundwater?

We are responsible for managing and allocating groundwater resources across NSW. We do this by using the best available science to inform our policy, and through legislation such as water sharing plans.  We also assess and report on the condition of the state’s groundwater resources. You can view the groundwater data we use to monitor groundwater levels via the Real-time data website. Groundwater flow models also help guide our long term decision-making for groundwater management.

What is groundwater?

Groundwater is the water contained within saturated rocks and sediments below the land surface. Groundwater moves slowly. It connects to rivers, streams, lakes and wetlands. It feeds trees and vegetation, and it can be thousands to more than a million years old.

Groundwater behaves differently to surface water. Under natural conditions, groundwater moves along flow paths from areas of recharge to areas of discharge. Recharge is the movement of water into a groundwater system from rainfall, flooding, rivers or streams. Under natural conditions, groundwater discharges into springs, lakes, rivers or wetlands. Groundwater levels can change naturally over time due to changes in weather patterns and climate. Groundwater levels can also be impacted by changes caused by humans, such as wells or bores that are dug or drilled deep enough to withdraw groundwater. Extraction also has the potential to alter the natural flow path of groundwater.

Although groundwater occurs everywhere below the ground, it is unevenly distributed in both quantity and quality. The ability to get water out of the ground (yield) and the quality of the water varies depending on the geology and the climate. Some groundwater is fresh and suitable for drinking. Other groundwater can be salty or contaminated, making it unsuitable for some uses.

Groundwater becomes particularly important as a source of water during drought, when rivers and creeks run dry and in areas at distance from rivers.

What is a groundwater system?

A groundwater system is any type of saturated sequence of rocks or sediments that allows groundwater to flow through the spaces between grains of sand, gravels and other alluvium or cracks in rocks. Thick sequences can store and transmit large volumes of groundwater, whilst others may only yield small quantities.

What is an aquifer?

The term 'aquifer' is commonly understood to mean a groundwater system that can yield useful volumes of groundwater. This also implies that the water is of good enough quality to be used for purposes such as irrigating crops or for town or stock drinking water.

Why manage groundwater?

Groundwater is an important source of water for towns, industries and irrigators who rely on groundwater extraction to support their activities. Also, many landholders rely on groundwater for domestic and stock use. Groundwater is also important for the environment. It supports some ecosystems and provides base flow to rivers.

Over-extraction or contamination of groundwater can have serious, long-term and sometimes permanent impacts on the groundwater system. This may ultimately reduce the volume and quality of water available for the users and ecosystems that depend on this groundwater

How is groundwater managed in NSW?

In New South Wales groundwater is managed at two scales:

  1. At a regional level known as the 'water source' scale, and
  2. At a local level between individual bores.

The volume of water that can be taken from a water source is defined in the  water sharing plan for that water source. Water sharing plans  apply to all surface water and groundwater in NSW. They manage water extraction for use by irrigators, industry, towns and communities to ensure there is water for the environment. The withdrawal  of groundwater in 240 water sources across NSW is managed by 50 water sharing plans.

Water sharing plans for groundwater sources aim to:

  • minimise extraction impacts on groundwater dependent ecosystems
  • minimise extraction impacts on cultural and spiritual values of groundwater
  • protect the structural integrity of aquifers and groundwater quality
  • ensure no long-term declines in water levels
  • preserve basic landholder rights access to groundwater
  • ensure fair, equitable and reliable access to users of groundwater
  • enable water trading between users.

When groundwater is withdrawn from a bore, the water level declines immediately around the bore.   The depth and extent of this ‘cone of depression’ varies depending on the characteristics of the groundwater system. When there are several bores in an area, the water level can decline over a larger area. To ensure these local impacts are monitored and managed,  all applications for new bores and trades are individually assessed.

Groundwater sources are divided into four broad hydrogeological types:

  • alluvial (unconsolidated sediments)
  • coastal sand (unconsolidated sediments)
  • porous rock (consolidated sedimentary rocks)
  • fractured rock (igneous and metamorphic rocks).

A groundwater source can include a number of groundwater systems based on geological formation types. Groundwater sources can overlie one another causing part or all of another groundwater source to be buried.

Information for groundwater users during drought

We have prepared a number of additional information resources aimed at assisting water users impacted by drought. Groundwater users may find reducing groundwater allocations and assessing groundwater applications useful.