From http://ottawa.ca/en/residents/recreation-and-parks/swimming#wading-pools
The Champlain Park wading pool schedule is:
Season July 4, 2017 to August 28, 2017
Monday 11 am to 6 pm
Tuesday Noon to 7 pm
Wednesday Closed
Thursday Noon to 7 pm
Friday 11 am to 6 pm
Saturday Noon to 5 pm
Sunday Noon to 5 pm