  SrRuO$_3$, a ferromagnet with an approximately 160\,K Curie temperature,
exhibits a $T^2$ dependent dc resistivity below $\approx$ 30 K. Nevertheless,
previous optical studies in the infrared and terahertz range show non-Drude
dynamics at low temperatures which seem to contradict a Fermi-liquid picture
with long-lived quasiparticles. In this work, we measure the low-frequency THz
range response of thin films with residual resistivity ratios, $\rho_{300K}/
\rho_{4K} \approx$ 74. Such low disorder samples allow an unprecedented look at
the effects of electron-electron interactions on low-frequency transport. At
temperatures below 30 K, we found both a very sharp zero-frequency mode which
has a width narrower than $k_BT/\hbar$ as well as a broader zero frequency
Lorentzian that has at least an order of magnitude larger scattering rate. Both
features have temperature dependencies consistent with a Fermi-liquid with the
wider feature explicitly showing a T$^2$ scaling. Such two -Drude transport
sheds light on previous reports of the violation of Mathielssen's rule and
extreme sensitivity to disorder in metallic ruthenates. We consider a number of
possibilities for the origin of the two feature optical conductivity including
multiband effects that arise from momentum conserving interband scattering and
the approximate conservation of a pseudo-momentum that arises from quasi-1D
Fermi surfaces.
