Water is an essential requirement for electricity generation. Over the past 18 months, we have evolved our operations to ensure sustainable water management and use at our sites. Our decision-making regarding water takes a balanced approach, considering the needs and priorities of other users, our operations and National Electricity Market conditions.
Balancing our water usage needs with local communities and broader energy users
Boondooma Dam is the primary source of water for Tarong power stations. The dam was purpose built to provide water to the power station. Our high priority water allocation from Boondooma Dam means we pay a premium price to ensure water security, with water the single biggest operating cost at Tarong power station.
Tarong power stations also have access to water from Lake Wivenhoe; however a substantial premium is paid for this water. Generally, we draw water from Lake Wivenhoe when Boondooma reaches 34 per cent capacity as we need to keep the cost of generation low in order to maintain downward pressure on wholesale electricity prices. However, in April 2019 after considering the current and future impact of drought conditions and the North and South Burnett communities’ dependence on the Boondooma water supply, we started drawing water from Lake Wivenhoe before the 34 per cent threshold was reached. We currently draw 68 per cent of water required for generation at Tarong power station from Boondooma Dam, with 32 per cent sourced from Lake Wivenhoe.
We will continue to monitor dam levels at Boondooma Dam so we can respond to any potential water shortage by increasing supply from Lake Wivenhoe. We also discharge excess water from our operations back to Meandu Creek Dam, supplying irrigators along Meandu Barker Creek.
Working with the community to shape our water strategy
In the past five years, we have built and maintained strong relationships with other water users, taken on board their feedback, and kept the community informed as part of our planning processes.
We regularly meet with the Meandu Barker Creek Water Advisory Committee which includes downstream users and irrigators, to openly discuss their preferences and our long-term water strategy.
In October 2018, we assisted the Meandu Barker Creek Water Advisory Committee to hold its Annual General Meeting and elect a new committee. This committee and other users were invited to Tarong power stations in December 2018 and again in June 2019.
One of the issues raised by this group included a perception that Tarong power station water releases contributed to an overall increase in salinity levels within the groundwater catchment that Nanango’s town water was drawn from.
A proactive approach has been implemented whereby Stanwell employees undertake additional sampling prior to each meeting to provide assurance and confirmation that the water discharges into the creek are both within Environmental Authority limits and further, not contributing to the broader salinity challenges for this locale.
Over the past 12 months, we also hosted two BBQs with other water users at Tarong power stations to provide them with information on Stanwell’s water strategy.
Our sustainable water practices
Tarong power stations have been reusing cooling tower blowdown water to replace Boondooma Dam water. To enable this, we required approval to increase salinity discharge limits under the power station’s Environmental Authority. Under the current approval, when Boondooma Dam is at 40 per cent, we are able to increase the number of times we recycle water through the site, in order to conserve water. The number of cycles is increased again when Boondooma Dam levels drop to 30 per cent. While the water we release into Meandu Barker Creek has a higher level of salinity as a result, it does meet the environmental release limits which have been put in place to protect the ecological values of the creek.
As required under our Environmental Authority, we undertake aquatic ecosystem surveys every three years or if conditions change, for example if we were to commence releasing a greater volume of water or water of a higher than normal salinity to Meandu Barker Creek. The surveys have indicated that our operations at Tarong power stations are not having an adverse impact on the ecosystem health of the creek. After each survey is completed, we share a summary of the results with the Meandu Barker Creek Water Advisory Committee who then distribute this information more widely with other downstream water users.
We will continue to look for additional cost-effective opportunities to reduce our overall water consumption and will continue to engage with local communities and other users to ensure responsible and sustainable use of water resources. We are currently working with Seqwater to develop a strategy to ensure Tarong power stations can use Purified Recycled Water (PRW) once the Western Corridor Recycled Water Scheme is re-commissioned and investigating solutions to issues associated with PRW and discharge limits in Meandu Barker Creek.