Collier Preserve, formerly Mill Creek Preserve, was acquired by the MetroParks in 2005 to protect its sensitive forested wetland habitats along Mill Creek.

Featuring 300+ acres, approximately seven miles of trails, an upland ridge overlooking the Mill Creek Valley, a wooded ravine, several small streams, forests, fallow fields, and a ridge of densely covered vegetation, the preserve creates many opportunities for bird watching, hiking, and other passive recreation activities. Several extensive restoration projects added acres of wetland and prairie habitat to the facility.