A weir is a low-rise dam or simply a wall built across a river to raise the water level. When water goes over the weir, it rushes downstream like in a waterfall.

A waterfall hard to see from above, with dangerous recirculating water below

Picture yourself in a boat coming from the left of the photograph. Up ahead, there is a weir, but all you see is a calm surface stretching out to the horizon. When you reach the crest, you’ll be in serious trouble.
Downstream of the weir, you're not safe either. The recirculating water at the bottom of the weir can flip a boat or drag a swimmer under. Even if weirs are not very high, they are still very dangerous.

How to stay safe near weirs

  • Never go near a weir.
  • Obey all warning signs and never cross booms.
  • Don’t go fishing at the bottom of a weir, and always obey the warning signs.

Video: Staying safe near a weir

A weir is a man-made waterfall that poses two easily avoided risks. Watch the video to learn more.