N.H. Rev. Stat. Ann. § 35-B:6

All public property may be used for leisure time activities, provided that prior approval for its use has been granted by the appropriate authority in charge of that property. A cooperating agency may establish its own system of just compensation for the use of such properties. Similarly, any authority or body in charge of any public property may refuse use of its property for leisure service activities if interference in the intended use of the property would result.