The scheme

Arrow's approach to beneficial use of coal seam water aims to provide it to existing Condamine Alluvium groundwater licence holders.

Instead of pumping groundwater from the Condamine Alluvium, participants will use Arrow’s treated water. This arrangement is called the Condamine Alluvium Substitution Scheme (CASS).

The scheme is intended to offset impacts to the Condamine Alluvium aquifer arising from Arrow’s coal seam gas (CSG) production in the area of greatest predicted CSG-caused drawdown.


A portion of Arrow’s Surat Basin tenure lies across the Condamine Alluvium, a critical groundwater resource for agriculture.

A direct evaluation of connectivity between the Condamine Alluvium aquifer and the Walloon Coal Measures (Arrow’s target formation), conducted at two sites in 2013 and 2014, in addition to studies undertaken by the Queensland Government’s Office of Groundwater Impact Assessment (OGIA), demonstrated a low potential for groundwater impact from CSG extraction.

Groundwater modelling by OGIA has shown that, while connectivity between the Condamine Alluvium and Walloon Coal Measures is low, the volume of groundwater in the Condamine Alluvium will be slightly reduced because of CSG-related groundwater pumping from the underlying Walloon Coal Measures. The volume that is due to Arrow's activity is estimated at about 58GL over 100 years (or about a tenth of Sydney Harbour's volume). This may change over time, based on the amount of water extracted through CSG production and updated groundwater modelling.

Of note

  • The amount of water removed from coal seams during Arrow’s gas production will dictate the amount of water available under the scheme.
  • The timing and amount of water available under the scheme also depends on the phasing of Arrow’s development activity across its tenure.
  • The EOI seeks to evaluate the level of interest in participation in the scheme area shown in the information pack (available below).
  • If the EOI process does not identify enough participants, Arrow may not proceed with a formal selection process.
  • If a formal selection process is undertaken and it does not identify enough participants to achieve the full substitution target, Arrow may not proceed with the scheme, and may pursue other offset options.