Some things do need permits (they're sold/issued to prevent overcrowding at some public park spaces); I'm not certain whether this would apply in your circumstances, but they're generally based on the specifications (size) of the boat, etc. I suggest going to the official city/county website & looking into the details there-- it's always better to avoid a fine if you happen to encounter any enforcement.
Call, Denver Parks Department.
Zach's right
Im sure you could people bring there own boats all the time
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