  Results of in-plane and out-of-plane thermal conductivity measurements on
$\rm La_{1.8-x}Eu_{0.2}Sr_xCuO_4$ ($0\leq x\leq0.2$) single crystals are
presented. The most characteristic features of the temperature dependence are a
pronounced phonon peak at low temperatures and a steplike anomaly at $T_{LT}$,
i.e., at the transition to the low temperature tetragonal phase (LTT-phase),
which gradually decrease with increasing Sr-content. Comparison of these
findings with the thermal conductivity of $\rm La_{2-x}Sr_xCuO_4$ and $\rm
La_2NiO_4$ clearly reveals that in $\rm La_{2-x}Sr_xCuO_4$ the most effective
mechanism for phonon scattering is impurity-scattering (dopants), as well as
scattering by soft phonons that are associated with the lattice instability in
the low temperature orthorhombic phase (LTO-phase). There is no evidence that
stripe correlations play a major role in suppressing the phonon peak in the
thermal conductivity of $\rm La_{2-x}Sr_xCuO_4$.
