The problem with gods/goddesses in the landscape is difficult to discuss on TMA - due to the problem Tombo identified, and to the understanding of mythology and religion within the context of our neolithic/bronze age sites.
Anglo-saxon modern secularism stands in the way, and the other, just as important thread of the "why" is not touched upon.

But to go back to Tombo's piece, and his assertion that, (Julian Cope also makes the same point) Sil could be identified with Suil, the eye goddess found in other cultures, he sees it as the "solar" eye, not in this instance as a water goddess which Sulis at Bath was. The "Silbury Game", which I photographed on Sunday is, seeing Silbury as a great omphalos in the centre of a sacred landscape, the "eye goddess" game as you view Silbury coming down The Ridgeway, or sighting on it from the Sanctuary, WKLB or Overton barrows....

So is the water goddess Sulis a larger mythological territorial goddess, encompassing the area around Silbury, springs, rivers and wells; Stonehenge, river and (latest theory) healing waters from Preseli maybe; and Salisbury, celtic derivation - Sorviodunum, which I think is by a conjunction of rivers; not of course forgetting Stanton Drew with its avenues down to the River Chew. Enter the world of mythology and you may find the answer ;)