Technically no, but i'm not sure how they would check to see if you had paid if you didn't park there. That being said, it's not expensive to use for the day or even to get a year pass. They do rely on that money to help maintain the park and keep it nice for everyone to use.
Please consider joining Friends of Harbison State Forest. This is a group of volunteers that maintain and create the trails The cost is only $25 per year and you get a monthly informative newsletter
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