The purpose of the Stone Lake property, in Sacramento County, is to preserve and protect two rare natural Central Valley lakes and their surrounding riparian habitat and grassland areas. The property lies within the Pacific Flyway and provides wintering grounds for a variety of waterfowl and other migratory birds, as well as habitat for indigenous species such as the listed Swainsons hawk, the giant garter snake and the longhorn elderberry beetle. The property contains a number of Native American occupancy sites. Located on the southern edge of the Sacramento metropolitan area, the property serves as valuable urban open space.