Limestone Canyon is prized for its great beauty and natural biological diversity.

Within the boundaries of the The Irvine Ranch^®, a national model of habitat conservation and management is at work protecting entire natural communities and the many birds, reptiles and other animals that depend on them for survival. Known as The Nature Reserve of Orange County, it is a collaborative, multi-agency effort that plays a vital role in ensuring the long-term conservation of the reserve’s sensitive resources.

Until 1991, habitat and wildlife protection in Orange County and elsewhere in California occurred on a project-by-project basis that usually focused on a single species.

The Nature Reserve of Orange County was created in 1996 when 37,000-acres of land were set aside for permanent protection – 21,000 acres contributed by The Irvine Company, and 16,000 acres from other entities. Much of that land falls within the boundaries of the larger Irvine Ranch Land Reserve and includes protected areas in and near the Orange sphere of influence.

The Nature Reserve of Orange County plays a key role in the protection and management of sensitive natural communities on The Irvine Ranch. According to its mission statement, it was created "To ensure the persistence of the reserve’s natural communities…through the protection, study and restoration of native habitats and natural processes." As just one example of its large scale conservation efforts, The Nature Reserve of Orange County protects and restores local coastal sage scrub habitat, which supports species that are rarely found in other parts of the world. Through its comprehensive approach to protecting and managing entire natural communities, The Nature Reserve of Orange County is helping to ensure that our rich natural heritage will be conserved for generations to come. In October 2006, the U.S. Secretary of the Interior designated The Irvine Ranch National Natural Landmark (NNL)-a 37,000-acre expanse of land singled out for its nationally significant scientific values. The NNL lands are owned by the County of Orange, City of Irvine, The Irvine Company, The Nature Conservancy and California State Parks. They are filled with unusual and rare geological characteristics tracing Earth's history back 80 million years. Also rich in biology, they protect a wide variety of plants and animals, some endangered and others found nowhere else on Earth. The areas recognized by the NNL designation include Limestone and Fremont canyons in the East Orange area. For more information on the NNL please open the recent publication.