The Northern Spotted Owl was designated an indicator species in the old growth forests in the Pacific Northwest. In this region, environmental preservation efforts were thoroughly involved throughout the community yet timber harvesting was still a key economic dependency. In 1991, the "Seattle Audubon Society v. Evans" case maintained that the Forest Service must still comply with NFMA requirements even though the Northern Spotted Owl had been listed "threatened" under Endangered Species Act (ESA). The Forest Service claimed that once the owls became part of the Endangered Species Act's duties, it was then relieved of its own duties to maintain the viability of its population.