This is from page 95 of the WCHA guide:
 
...And since the Association's founding, the WCHA has qualified
at least one representative for the NCAA Championship, or 'Final
Four', every single season.
 
 
On the next page, they list all of the winners since 48. Michigan won
in 51, but it is not in bold, which means Michigan was not a WCHA
member then. The Maize and Blue won it again in 52 and that *is* in
bold, so they were a member then.
 
At other places in the guide, they say the WCHA was formed in 59.  The
league grew out of the Western Intercollegiate Hockey League, which was
founded in 51. I guess if the WIHL was formed over the summer of 51
then Michigan would have been the first winner from that league in the
spring of 52.
 
End of hockey history 101.
 
Keith