The extent of this tag <natural=water; water=stream> seems inappropriate, as the "median of the maximum water levels of all months of the year" should be mapped. This is here certainly not the case.

It also gives the wrong impression of a lake in this area, where it is actually just a riverbed.

It would be better to map just the main stream or the two or three most important streams here. The whole are should be tagged as 	waterway=riverbed

See also
https://wiki.openstreetmap.org/wiki/Tag:waterway%3Driverbank
and
https://wiki.openstreetmap.org/wiki/Proposed_features/waterway%3Driverbed