This 1948 advertisement says that they are “Opening Saturday, May 22”, but that was probably referring to opening for the season as the tourist booklet above suggests the cabins had been there since at least the mid-1940s.
It looks like plans changed for whatever reason because shortly thereafter the “Ottawa Beach Motel”, owned by Jor Defalco, appears on the same site.
Featuring the well known attached cabins and a bungalow, there was also apparently a dance hall, and presumably a bar.
Apparently in it’s day it was quite the “go to” place for dancing and and evening out. Just outside the then city limits probably meant it closed later than other establishments that were “in town.” Wild and crazy times.
According to comments posted on the Britannia Facebook Group, the Motel was converted to a halfway house facility in the 1970s, and torn down to create Andrew Haydon Park shortly thereafter.