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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 this description in the wiki page. Edit this description in the data item.
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 Mapnik
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