[jascii]

Being "naturally formed" isn't a requirement to be a river. Being gravity fed and naturally flowing is. A canal doesn't have significant flow.

[sva_]

But would you really call this concrete structure you see in the picture a river?

[rjbwork]

If the LA River can be a river, why not?

[EngManagerIsMe]

If the LA River is any historical precedent, yes.