Restrooms should be unlocked during normal park hours (posted by vehicular entrance to the park). Maintenance issues at Southeast Clarke Park should be reported to the Park Services Division at 706 - 613 - 3801. For rentals and other questions contact the Southeast Clarke Park office at the tennis center 706 - 613 - 3991.
If locked then an employee needs to unlock.
Generally the restroom is open. My guess is that if a code is required it's for staff only.
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