From OpenStreetMap Wiki
This is used to described different types of waterways. When mapping the way of a river, stream, drain, canal, etc. these need to be aligned in the direction of the water flow. See the page titled Waterways for an introduction on its usage.
|waterway||river||For narrow rivers which will be rendered as a line. For larger rivers see also waterway=riverbank (Other languages).|
|waterway||riverbank||Used for larger rivers in addition to waterway=river, to define an area between the opposite riverbanks. See water=river for alternative tagging.|
|waterway||stream||A naturally-formed waterway that is too narrow to be classed as a river. An active, able-bodied person should be able to jump over it if trees along it aren't too thick.|
|| A natural, dry (ephemeral) riverbed that contains water only during times of heavy rain or simply an intermittent stream, in semi-arid areas. Also known as a "Wash" in the deserts of America.
It has been recommended to stop using this tag. For intermittent waterways use waterway=river/waterway=stream + intermittent=yes. For valleys natural=valley.
|| Dry stream bed - negative forms of erosion relief formed by the activity of temporary streams.
Don't use this tag. For intermittent waterways use waterway=stream + intermittent=yes. For valleys use natural=valley.
Man made waterways
|waterway||canal||An artificial open flow waterway used to carry useful water for transportation, waterpower, or irrigation. (Other languages).|
|waterway||pressurised||A waterway where water is pipe flowing in closed space without air.|
|waterway||drain||An artificial free flow waterway used for carrying superfluous water like storm water or industrial discharge.|
|waterway||ditch||An small artificial free flow waterway used for carrying superfluous water along paths or roads for drainage purposes.|
|waterway||fairway|| A navigable route in a lake or sea marked by buoys.
This value is questioned and conflicts with seamark:type=fairway.
|waterway||dock||An 'enclosed' area of water used for building or repairing ships.|
|waterway||boatyard||Boat yard – a place for constructing, repairing and storing vessels out of the water.|
Barriers on waterways
|waterway||dam||A wall built across a river or stream to impound the water. A dam normally does not have water flowing over the top of it.|
|waterway||weir||A barrier built across a river, sometimes to divert water for industrial purposes. Water can still flow over the top.|
|waterway||stream_end||The natural end of a stream (where it seeps into the ground).|
|waterway||waterfall||A waterfall, use in combination with natural=cliff|
|waterway||lock_gate||To mark the position of gates at each end of a lock. Alternatively, for smaller locks use a single lock=yes node in the middle of the lock.|
Other features on waterways
|waterway||turning_point||A place to turn the driving direction for vessels, where the boats are longer than the river/canal is wide. Use maxlength=* to denote the maximum length of the vessel.|
|waterway||water_point||A place to fill fresh water holding tanks of a boat.|
|waterway||fuel||A place to get fuel for boats.|
Some additional attributes for waterways
|intermittent||yes||Indicates that the waterway does not have a permanent flow (i.e. is sometimes/often dry).|
|seasonal||yes, spring, summer, autumn, winter, wet_season, dry_season||Indicates that a waterway has a seasonal (yearly cyclic) flow.|
|destination||name||Name of the body of water the linear feature flows into.|
|lock||yes||()||A lock is used for moving boats between waterways at two different levels. Can tag either the section of the way between the gates (detailed) or just a single node in the waterway (less detailed).|
|mooring||yes, private, no||A length of bank where boats are explicitly permitted to moor. maxstay=* should be used for timing information.|
|usage||transmission, irrigation, headrace, tailrace, penstock||A waterway=canal may have one (or more; separate with semicolons) uses.|
|tunnel||culvert||()||A short tunnel usually installed under roads, railways or building. Its size doesn't allow human to get inside and is as narrow as the structure is supposed to go under. For streams passing under a road in culverts use tunnel=culvert+layer=-1 on the section of stream passing under the road. Don't use either of these tags for streams passing under bridges.|
|tunnel||flooded||A long (>100m) tunnel where flowing water or other fluid prevent humans from safely walking inside despite its appropriate diameter or size. Water inside can be pressurised or not, used in combination with any waterway=* linear value.|
|waterway||user defined||All commonly used values according to Taginfo|