Water: -g, -d, -r

Basque <ur> "water" has the combining forms <ur->, <uh->, <ug->.
Given Miguel's or Vennemann's rules, it is difficult to reconstruct a
common pre-pre-Basque form from which all three could be derived
(possibly dialectally -g- > -h-?; *-R- > -r- / -h- /(-G- > -g-) would
make sense phonetically, but does not makes sense for Basque).
PIE has for water the rots *<w-r->, *<w-d->, *<w-g-> (among others).
Is this a coincidence? (d > h is problematical, perhaps one should
use the *w-s- (*w-z-?) "wetlands" root instead?)
(Normally *<w-gW-> is posited for the last of these, as far as I can
tell to account for the u-umlauted vowel in ON <vök> "hole in the
ice", but it could be a suffixed -w-).

Torsten