  We present further observational results on our Lya-only absorber
identification project at low and intermediate redshifts. We combine CFHT/MOS
imaging and spectroscopic observations of 25 galaxies in the field of the
quasar 3C286 (z_e = 0.849) with HST/FOS spectrum of the quasar between 1600 and
3000 A and HST/WFPC2 high spatial resolution imaging of some galaxies. Our
results confirm our first conclusions on the nature of the intermediate
redshift Ly-alpha forest absorbers. A small fraction of them is tightly linked
to galaxies, and most probably arise in the external parts of giant halos
(R~200 kpc with H0=50 km/s/Mpc) around fairly luminous galaxies (M_AB(B) < -19)
of various spectral and morphological types, as shown by HST imaging of these
objects. Most of the absorbing clouds appear to be only ``associated'' with
galaxies, in the sense that they could trace the gaseous filaments or sheets of
large-scale structures. Thus, as expected from a sample tracing large scale
structures, these galaxies have various spectral types. We also find that
groups of galaxies have always at least one associated Ly-alpha absorption
line.
