Another jewel will be added to Maricopa County Parks and Recreation's crown: Hassayampa Preserve MaricopaCounty Board of Supervisors voted this week to take one step closer to full management of Hassayampa River Preserve. The Nature Conservancy has agreed to donate 2 parcels of land to MaricopaCounty. Ultimately, Hassayampa will serve as the gateway to the much larger Vulture Mountains Recreation Area.