Yes it is but sometimes the swim team has meets there check if they do then i don't know
On Sunday it's open from 9 to 6 https://parks.ny.gov/parks/attachments/Riverbank2018-19AquaticSchedule-FallWinter.pdf
You can just buy tickets for today or whatever you want to swim. Tickets by the ice skating booth.
You know I passed by there at least a couple of times each week but I really can't give you an answer yes or no sorry
I really don't know.
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