A quick look at some of the data around the Rideau Canal Skateway seasons.
Opening and closing dates are taken from Wikipedia
Closing: https://en.wikipedia.org/w/index.php?title=Rideau_Canal&oldid=1177261832 Opening: https://en.wikipedia.org/w/index.php?title=Rideau_Canal&oldid=995637706
No particular reason for these revisions, I just recorded them on different days.
Closing date for the 1972-73 season is estimated as the Wikipedia article only gives the number of days it was open.
Note that the canal can have non-skating days during its "open" period, i.e. a warm stretch can close the skating rink before it is fully closed for the season.