Dams and weirs

Water storage is a critical part of our business, with the region’s drinking water predominantly sourced from dams. Our dams are used to provide a safe and sustainable water supply as well as to help manage and mitigate major flood events.

Seqwater owns and operates 26 dams, 48 weirs, and two borefields across the region.

Water from our dams is released to supply our drinking water treatment plants and irrigation schemes, as well as to provide environmental flows in downstream rivers and creeks.

While the primary purpose of our dams is to store water for drinking and irrigation, the lakes and surrounding area provide the community with recreation facilities.

What is a dam?

A dam is a wall of solid material built across a river valley or catchment to block the flow of the river. The dam wall allows water to pool behind it, forming a lake. 

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How are dams built?

Each dam is different – some are small and deep, some are shallow and wide. It all depends on the size of the river and shape of the valley. Dams can be made from different materials. There are two main types of dams:

  • concrete
  • earth and rock fill.

Concrete dams are made of strong, solid concrete walls that resist the pressure of water. Earth and rock fill dams have a solid core of clay in the middle to prevent water leakage, and an outer layer of rock for strength.

There are dams that are built with a combination of both concrete and earth and rock fill.

What is a weir?

A weir is a large wall that holds back water in the river so it can be slowly released downstream. They are designed to regulate water flow and are an important part of our water supply network. However, weirs can be dangerous and unpredictable as you never know when water will be released, or from which part of the weir.

Swimming or paddling in weirs, spillways, near dam walls, or in fast flowing waterways is fatal. Don’t put your life (or the life of others) at risk.

Exclusion zones have been established for the safety of all visitors. These areas are clearly marked with buoys on the water and warning signs are installed in ‘no go’ or exclusion zones.

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Why are weirs dangerous?

After heavy rain, an overflowing weir can become a drowning machine due to the volume of water flowing over the person underwater, making self-rescue, and even assisted rescue, almost impossible. Being swept over a flooded weir is like being dumped by a constant barrage of plunging water, with the churning water forcing you down.

Many people fail to realise that the faster water is flowing, the shallower it needs to be to sweep you over. Being a good swimmer has nothing to do with survival once you are trapped in the drowning machine.

It only takes:

  • ankle deep water to knock you off your feet
  • 60 seconds to drown
  • one second to rethink your decision – don’t get sucked in!

The best approach to weir safety is to avoid swimming in or playing near them. We have many great recreation areas at our lakes across the region where you can safely enjoy the water.

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