  Impurity scattering in the unitary limit produces low energy quasiparticles
with anisotropic spectrum in a two-dimensional $d$-wave superconductor. We
describe a new {\em quasi-one-dimensional } limit of the quasiparticle
scattering, which might occur in a superconductor with short coherence length
and with {\em finite} impurity potential range. The dc conductivity in a
$d$-wave superconductor is predicted to be proportional to the normal state
scattering rate and is impurity-{\em dependent}. We show that {\em
quasi-one-dimensional } regime might occur in high-$T_c$ superconductors with
Zn impurities at low temp\ eratures $T\lesssim 10$~K
