Tag:waterway=weir
 waterway = weir
|
 |
| Description |
|---|
A barrier built across a river to control water speed and depth. Water can still flow over the top. 
|
Rendering in openstreetmap-carto 
|
|
Rendering in openstreetmap-carto 
|
|
| Group: Waterways |
| Used on these elements |
    |
| Useful combination |
|
Status: approved
|
|
|
| Tools for this tag |
|
| Wikidata |
| Q1066997 |
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.
Rendering
| Type | Picture | Tags | OSM Carto |
|---|---|---|---|
 node
|
|
waterway=weir | 
|
 way
|
|
waterway=weir | 
|
See also
- waterway=dam - for a barrier where water does not flow over the top.
- landuse=reservoir or natural=water + water=reservoir for the water impounded behind a dam.
- waterway=fish_pass - as
natural=water + water=fish_pass - A fish pass, also known as a fish ladder, a fishway or fish steps, is a structure on or around artificial barriers (such as dams and locks) to facilitate diadromous fishes natural migration.
Weblinks
- Weir on Wikipedia