  We present constraints on the deuterium to hydrogen ratio (D/H) in the
metal-poor gas cloud at redshift $z=0.701$ towards QSO 1718+4807. We use new
Keck spectra in addition to Hubble Space Telescope (HST) and International
Ultraviolet Explorer (IUE) spectra. We use an improved redshift and a lower \HI
column density to model the absorption. The HST spectrum shows an asymmetric
Lyman-$\alpha$ (\lya) feature which is produced by either \HI at a second
velocity, or a high abundance of D. Three models with a single simple H+D
component give $8 \times 10^{-5} < D/H < 57 \times 10^{-5}$ (95%), a much
larger range than reported by Webb et al (1997a,b). A more sophisticated
velocity distribution, or a second component is necessary for lower D/H. With
two components, which could be a part of one absorbing structure, or separate
clouds in a galaxy halo, we find $D/H < 50 \times 10^{-5}$. We do not know if
this second component is present, but it is reasonable because 40 -- 100% of
absorption systems with similar redshifts and \HI column densities have more
than one component.
