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Public-images-osm logo.svg usage = tailrace
Waterway tailrace.jpg
Waterway specific usage dedicated to water release from turbines output after energy production Edit or translate this description.
Group: Railways
Used on these elements
should not be used on nodesmay be used on waysshould not be used on areasshould not be used on relations
Useful combination
Status: approvedPage for proposal


The tailrace at the end of millrace

Tailraces paths allow water to flow from turbines to natural environment in a power generation facility.
Most of the time, free flow canal are used as tailraces, they can be outdoor or in a tunnel depending of the environment.
Those canals aren't pipe flow (pressurised) since the pressure is converted into power with power=generator help.
A tailrace waterway can go through a tunnel=flooded, be in free space or even in a man_made=pipeline. Have a look below how to tag them according to this specific usage.

It may be possible to involve water release infrastructure in Relation:waterway with side_stream role only if all water is took and released in the same river. It's not always the case and waterway=* graph have to be extended with or without waterway relation membership.

How to map

Don't forget to have a look at Waterways or waterway=* for more complete tagging possibilities.
These guidelines are dedicated to usage=tailrace situations.

As any waterway and for power generation only, draw a line along the path followed by water. Put usage=tailrace on any segment between generators and release points you may see in a lake or a river.
Tailraces can length a few meters to kilometres depending on how far the plant is from the water release point.

Depending on power plant exploitation rules, water may flow intermittently. You can use intermittent=yes accordingly.


Photo Tagging Note
Tailrace outdoor canal


Outdoor canal releasing water out of an underground power plant. Water intermittently goes towards photographer.

See also