  In this paper, we use large-angle, nearby galaxy redshift surveys to
investigate the relationship between the 81 low-redshift Lya absorbers in our
HST/GHRS survey and galaxies, superclusters, and voids. In a subsample of 46
Lya absorbers located in regions where the February 8, 2000 CfA catalog is
complete down to at least L* galaxies, the nearest galaxy neighbors range from
100kpc to >10 Mpc. Of these 46 absorbers, 8 are found in galaxy voids. After
correcting for pathlength and sensitivity, we find that 22+-8% of the Lya
absorbers lie in voids, which requires that at least some low-column density
absorbers are not extended halos of individual bright galaxies. The number
density of these clouds yields a baryon fraction of 4.5+-1.5% in voids.
  The stronger Lya absorbers (10^{13.2-15.4} cm^-2) cluster with galaxies more
weakly than galaxies cluster with each other, while the weaker absorbers
(10^{12.4-13.2} cm^-2) are more randomly distributed. The median distance from
a low-z Lya absorber in our sample to its nearest galaxy neighbor (~500 kpc) is
twice the median distance between bright galaxies in the same survey volume.
This makes any purposed "association" between these Lya absorbers and
individual galaxies problematic. The suggested correlation between Lya absorber
equivalent width (W) and nearest-galaxy impact parameter does not extend to
W<200mA, or to impact parameters >200kpc. Instead, we find statistical support
for the contention that absorbers align with large-scale filaments of galaxies.
While some strong (W>400mA) Lya absorbers may be gas in the extended gaseous
halos of individual galaxies, much of the local Lya "forest" appears to be
associated with the large-scale structures of galaxies and some with voids.
