Bray Park Weir Tidal Protection Project
As part of its program of work to secure the Tweed’s water supply, Council requires an effective long-term solution that prevents saltwater from overtopping the Bray Park Weir and contaminating the weir pool.
Two options for raising the weir – by 1300 and 800 mm – are now being investigated. This investigation involves:
- detailed concept designs
- an environmental impact assessment involving flood studies
- stakeholder consultation including consultation with impacted signatories of a 1980 agreement on the weir.
Once the investigation is complete, a report will go before the elected Council for its consideration. The Council will then determine the next steps.
If you have a query, please read our frequently asked questions or ask a question using the tool below.
Why action on the weir is needed
The weir was built in the early 1960s to provide a water supply for most of the Tweed by creating a barrier between saltwater from the lower Tweed River and freshwater from the mid Tweed River.
Located on the upstream side of the weir is the weir pool – the source of fresh water for most Tweed households and businesses.
Since the weir was built, sea levels have risen due to climate change. High tides have become higher.
In 2017 and again in 2020, weather caused sea-level anomalies that combined with high tides, resulting in saltwater overtopping the weir and contaminating the weir pool. Both times, fast action from Council ensured the water supply was not interrupted. There is a significant risk this will not be the case in future events.
The rise of sea levels along with sea level anomalies will make overtopping events more frequent.
The current solution is temporary
Since 2017, Council 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.
Previous investigations
Council formed a project reference group in 2017 to identify and assess options to reduce the risk of saltwater contamination of the Tweed water supply. The group identified a range of options including:
- a hinged barrier across the entire weir
- continued use of concrete blocks
- narrowing the weir
- moving the intake of the Bray Park Water Treatment Plant
- raising the weir.
After the group recommended a hinged barrier, consultants engaged by Council conducted a detailed investigation, which found this option unworkable.
The group ranked other options, including narrowing the weir and raising the weir.
An investigation by consultants into narrowing the weir determined this option unviable because it would provide limited protection to the water supply.
The continued use of concrete blocks doesn’t provide adequate protection against overtopping events and the manual installation and removal of the blocks is unsafe.
Moving the intake of the treatment plant upstream would significantly reduce the catchment area of the Tweed district water supply, decreasing the amount of water available for most of the Tweed.
Sign up for email alerts when Council deploys blocks
Until a long-term solution is implemented, Council will continue to deploy concrete blocks when overtopping events are forecast.
To receive email alerts before blocks are deployed, please email your full name and email address to wateradmin@tweed.nsw.gov.au (Subject: Weir Alert).
We will provide at least 3 hours’ notice of a deployment.
Large diameter pipes or ducts , angled on the upstream side , that closes as the tide rises . Heavy duty construction with deflectors on the upstream side for flood debris.
the most simple solution would be to construct a concrete wall on the existing weir to the required height tying into the banks and have 20mm aluminium gates fabricated to suite openings in wall with some sought of angled steel configuration on upstream side to allow debris from high volume flows to be washed over wall to stop damage to wall . which would not change existing water levels upstream.
d phillips
Hi Mathuranatha Das, I would be very interested to hear some of the options you mention that would negate the need to raise the weir wall. Cheers
To stop salt water flowing up-steam over the weir does not necessarily mean the weir has to be raised [ an 18th Century solution ] In this day and age there are innumerable one way flow options that can prevent water flowing upstream without raising the height of the weir pool and its volume by trillions of litres .
Adding a huge volume of water to the permanent weir pool would greatly increase the frequency and severity of flooding
The circumstances that have caused the salt water ingress are all natural occurrences. I note there are many countries tackling this very subject.
Many indicate raising the levels of the levee would be helpful. I have looked at the idea of using sensors across the weir face which would at the first detection of salt water would immediately cause the raising of barriers to exclude the salt water.
Another option is to install permanent barriers to ensure the preclusion of any back flow of water or inundation by salt water.