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Public-images-osm logo.svg waterway = weir
Alifakovac Miljacka.jpg
A barrier built across a river to control water speed and depth. Water can still flow over the top. Edit or translate this description.
Rendering in openstreetmap-carto node
Weir node.svg
Rendering in openstreetmap-carto way
Group: Waterways
Used on these elements
may be used on nodesmay be used on waysshould not be used on areasshould not be used on relations
Useful combination
Status: approvedPage for proposal


A barrier built across a river, sometimes to divert water for industrial purposes. Water can still flow over the top. In the US this is often called a low-head or low-rise dam.

How to map

To map a small weir add a node along a river and tag it waterway=weir. If the weir has a name tag it name=*.

If the weir is long enough to be mapped as a way, create a way along the length of the weir and tag it waterway=weir. Again, add a name=* if it is known. The waterway=weir should share a node with the river where they cross. Like a natural=cliff the line direction matters: On the left side there is the high side, on the right side is the lower side.

Sometimes a fish pass is related with the weir.

(High-)ways over a weir

This subject was not part of the proposal but the most straightforward solution is that the highway=* and waterway=weir share a way. A section of this way may be marked with ford=yes if there is a ford.

Validators and QA tools may complain about this combination because they may have an overly generic rule saying that highways and waterways can not share a single way - this is one of the valid exceptions and tools should be fixed to accept it.


Type Picture Tags OSM Carto
Mf node.svg node Rhin-Grosser-Schleusengraben-15-XI-2007-130.jpg waterway=weir Render weir.jpg
Mf way.svg way Alifakovac Miljacka.jpg waterway=weir Render weir2.jpg

See also