Frequently asked questions
Has Council resolved to raise the Bray Park Weir?
Not yet. On 11 December 2024, Council resolved to further investigate raising the weir by 800mm, which may allow for future scaling to 1300mm if needed. Targeted community consultation will continue.
Why investigate raising the weir when the project reference group considered this option unacceptable?
Unfortunately, investigations have rendered other options unfeasible.
A detailed investigation into the hinged barrier, as recommended by the project reference group, determined that a hinged barrier would not be viable or resilient.
The present practice of placing concrete blocks, the second-ranked option of the group, does not fully mitigate the risk of saltwater contamination and is unsafe.
Detailed investigations into narrowing the weir, the third-ranked option of the group, found narrowing would provide limited protection.
Has Council considered scientific data to quantify the effect raising the weir would have on flood flows?
Yes, an options assessment of the 2 weir-raising options was undertaken by independent consultants GHD in September 2024. The assessment included flood and inundation impact studies. More details are available in the GHD Bray Park Weir Raising Assessment.
If Council raises the weir, what compromises could be made including negations of compensation with affected landowners?
Should Council resolve to raise the Bray Park Weir, we would negotiate with impacted signatories of a 1980 agreement into the weir.
Why is Council looking at raising the weir?
The weir is under increasing risk of saltwater overtopping due to rising sea levels. This jeopardises the supply of tap water for most of the Tweed. Raising the weir would safeguard this essential water source for years to come.
How often is the weir being overtopped by saltwater and blocks deployed?
From 1 January 2017 to 2 October 2024, there have been 90 overtopping tidal events, 66 requiring blocks to be deployed for a total of 570 days to prevent saltwater entering the weir pool. This has become a problematic risk to manage, with overtopping events occurring more frequently and on occasions twice a month. The frequency of events is well in excess of that predicted by the Water Research Laboratory.
In the past year, the fishway has been blocked for 158 days to prevent saltwater from contaminating the Tweed District water supply. Any mitigation measure to prevent the saltwater contamination will need to consider fish passage.
What are the differences between raising the weir by 800 mm and by 1300 mm?
Raising the weir by 800 mm would protect our water supply from saltwater contamination until around 2050, while raising it by 1300 mm would extend protection until 2100. More details are available in the GHD Bray Park Weir Raising Assessment.
Would raising the weir increase flood risks upstream?
There would be increases in water levels during floods immediately upstream of the weir. However, further upstream the increase would be minimal. For example, at Byangum Bridge, the increase would be about 10 mm during large floods. More details can be found in the GHD Bray Park Weir Raising Assessment.
Can’t we continue to rely on weir blocks?
Since 2017, our workers have been managing overtopping events by manually installing concrete blocks to narrow or block the weir. The blocks are removed when the risk has passed. While the blocks reduce the risk of saltwater contamination, they don’t fully mitigate the risk and the manual installation and removal is a safety concern. The fish ladder in the weir must also be blocked in these events, impacting the movement of fish in the river.