I've only just picked up Francis Pryor's book 'Britain BC' where he also comments on this river/Avenue link:
"Mike [Parker-Pearson] and Ramilisonina see the Avenue as a symbolic dryland continuation of the river (which may help explain its two changes of direction). We may imagine funeral parties leaving Durrington Walls or Woodhenge, possibly taking a boat along the river and then passing along the Avenue through no man's land to the Stones within their circle at the very heart of the realm of the ancestors."
I hadn't read this when I formed my own theory about the Henge/River/Avenue/Stonehenge link, but as I said at the time:
"I must be the millionth person who's thought of this!"
Something is not right. This message is just to keep things from messing up down the road