Great pictures, thanks. I solo canoed down it yesterday [plus labrador] from a put in near Hampton Poyle to Oxford There was a fair few trees and branches across it and a couple times, I climbed onto a branch to haul the canoe over. I also saw branches cut by a saw in the middle of the river, which means someone else had been there.
I asked because a series of fishermen, of varying levels of grumpiness, told me 'this is an unnavigable river', which confused me at first, until their meaning was clarified. This was news to me, so I had a bit of a google today and it seems the question of 'public right to navigation' is unclear with both sides arguing their position is definitive.
I did think going on to the bank to get around a weir might be a trespass, but even that is [depending on one's PoV] acceptable. As it was, i lined the canoe down the only weir i met, so did not ever get out of the water.