Bray Park Weir Tidal Protection Project

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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.


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.


Discussions: All (6) Open (4)
  • Criteria a Solution or mix of Solutions must meet

    by BrendaH, over 5 years ago
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    Please add to the Criteria below that you would like a Solution or mix of Solutions to meet. 

    ·  Not permanent

    ·  Deployable in 8 hours

    ·  Durable for flood

    ·  Acceptable TDS or range of acceptable TDS

    ·  Cost effective

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  • Solutions or mix of Solutions

    by BrendaH, over 5 years ago
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    Please nominate Solutions or a mix of Solutions to be considered by the Project Reference Group.


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  • Flood gate operations and the role they serve

    by BrendaH, over 5 years ago
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    I am curious as to the flood gates operations and the role they serve. I’ve always been of the mind set that these gates are in place to prevent salt water feeding back into the cane drains to protected the cane and the soil from the salt, if that is not the case could you please clarify what their roll is please.

    We had meetings with cane farmers and I was fairly sure this was the roll flood gates played for the cane farmers. I would appreciate some clarification on this. 

    Regards Pryce Allsop 


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  • Understanding of the datums

    by BrendaH, almost 6 years ago
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    AHD (Australian Height Datum) is also functionally the same as MSL - mean sea level. This is a height datum point = 0m

    However, tides are based on LAT - Lowest Astronomical Tide, which is effectively the lowest tide of the year and this datum is also 0m. (But a different 0m).

    We should never see a low tide with a minus sign. We do, but this is due to meteorological factors like high pressure systems, off shore winds etc.

    Based on the NSW Ocean and River Entrance Tidal levels 2104-2015, the difference between AHD and LAT for the Tweed River is 0.893m

    So if a tide chart shows a high tide at the Tweed River mouth of 2.0m, the water level would be 2.0 - 0.893 = 1.107 AHD.

    I hope this helps.

    Peter Robson

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  • Values

    by BrendaH, almost 6 years ago
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    CLOSED: This discussion has concluded.

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    What Values do you want the solution or mix of solutions to this issue to adhere to? 

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  • Measurements

    by BrendaH, almost 6 years ago
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    What measurements would you put in place to measure the effectiveness, cost/benefit etc of the solution or mix of solutions? 

    Replies Closed
Page last updated: 08 Dec 2023, 03:26 PM