We returned 634 million cubic metres of water to the environment in 2003.

• 60 operations return water to the environment. However, the definition for water return does not include evaporation, seepage and water entrained in product.
• At some operations, water is managed to prevent its return to the environment under all, or specific, environmental conditions. This may be for the protection of local ecosystems and may also be a permit or regulatory requirement. For example, Coal & Allied's operations are managed in accordance with the Hunter River Salinity Trading Scheme. The scheme manages the total allowable discharge of saline water into the Hunter River by issuing dischargers' with tradeable salinity credits. At the same time, saline discharge opportunities are reliant on high river flow rates and low background salinity levels so that salinity targets are not exceeded.
• The two operations that withdrew the most water from lakes, dams and permanent streams in 2003, IOC Carol Project and QIT Sorel also returned the majority (88 per cent and 97 per cent respectively) to the same environment.

When water is returned to the environment it is potentially available for other uses. However, its quality can have impacts on the environment and other users as it may contain metals and process chemicals that have been used in the extraction of metals and minerals. As with water withdrawal, there may be better measures that give an indication of the impact of returning water to the environment. At present, we report the discharge of potential contaminants and compliance with local regulatory limits for discharge. The latter assumes that a risk based assessment has been used to derive permit limits which are appropriate for the receiving environment.