The Carew River is a tributary of the Dolgleddau, or Cleddau, River in Pembrokeshire. I can't see it listed on the latest index.
Also, I'd like advice on whether this particular shot is eligible for the group. The stretch of river it shows is actually a tidal pond, created by a dam just downstream. So, it's a river, but also a pond. Can it go in the group?
River Carew (RNBCarew) added to the index. In practice it is almost impossible to make a simple water-tight definition of a river, but essentially it is water naturally flowing from springs to the sea. Even the distinction between river, canalised river, and canal is pretty arbitrary, as is the distinction between river and lake. There is certainly a place for the Carew in the RNB pool, so it is welcome. Please tag the photo.