  We have measured soft x-ray photoemission and O 1{\it s} x-ray absorption
spectra of Ca$_{1-x}$Sr$_x$RuO$_3$ thin films prepared {\it in situ}. The
coherent and incoherent parts have been identified in the bulk component of the
photoemission spectra, and spectral weight transfer from the coherent to the
incoherent part has been observed with decreasing $x$, namely, with increasing
orthorhombic distortion. We propose that, while the Ru 4d one-electron
bandwidth does not change with $x$, the distortion and hence the splitting of
the $t_{2\text{g}}$ band effectively increases electron correlation strength.
Although strong mass enhancement is found in the electronic specific heat data,
the coherent part remains wide, suggesting enhanced band narrowing only in the
vicinity of {\it E$_{F}$}.
