Grand Canyon National Park

Outstanding Universal Value

Brief synthesis

The Grand Canyon is among the earth’s greatest on-going geological spectacles. Its vastness is stunning, and the evidence it reveals about the earth’s history is invaluable. The 1.5-kilometer (0.9 mile) deep gorge ranges in width from 500 m to 30 km (0.3 mile to 18.6 miles). It twists and turns 445 km (276.5 miles) and was formed during 6 million years of geological activity and erosion by the Colorado River on the upraised earth’s crust. The buttes, spires, mesas and temples in the canyon are in fact mountains looked down upon from the rims. Horizontal strata exposed in the canyon retrace geological history over 2 billion years and represent the four major geologic eras.

Criterion (vii): Widely known for its exceptional natural beauty and considered one of the world's most visually powerful landscapes, the Grand Canyon is celebrated for its plunging depths; temple-like buttes; and vast, multihued, labyrinthine topography. Scenic wonders within park boundaries include high plateaus, plains, deserts, forests, cinder cones, lava flows, streams, waterfalls, and one of America’s great whitewater rivers.

Criterion (viii): Within park boundaries, the geologic record spans all four eras of the earth's evolutionary history, from the Precambrian to the Cenozoic. The Precambrian and Paleozoic portions of this record are particularly well exposed in canyon walls and include a rich fossil assemblage. Numerous caves shelter fossils and animal remains that extend the paleontological record into the Pleistocene.

Criterion (ix): Grand Canyon is an exceptional example of biological environments at different elevations that evolved as the river cut deeper portraying five of North America’s seven life zones within canyon walls. Flora and fauna species overlap in many of the zones and are found throughout the canyon.

Criterion (x): The park’s diverse topography has resulted in equally diverse ecosystems. The five life zones within the canyon are represented in a remarkably small geographic area. Grand Canyon National Park is an ecological refuge, with relatively undisturbed remnants of dwindling ecosystems (such as boreal forest and desert riparian communities), and numerous endemic, rare or endangered plant and animal species.

Integrity

At nearly 500,000 hectares, and with 94% of the park managed for wilderness values, the property is large enough to ensure protection of all the geological and geomorphological values for which it was inscribed. Scenic values are also well protected, though these can be significantly impacted by air pollution originating from outside park boundaries. Natural quiet, an important component of the visitor experience, is impacted by aircraft overflights and other human caused sounds in some parts of the property. While visitor numbers can be considered high, impacts are concentrated in the relatively small part of the property that is developed.

The hydrological and ecological health of the Colorado River and its associated riparian zones have been altered and deteriorated since the building of the Glen Canyon Dam upriver from the property, completed in 1963. Work is on-going to modify flows from Glen Canyon Dam to promote additional restoration of near shore habitats and resource conditions.

Uranium mining has occurred outside park boundaries and is governed by a 2011 Secretarial decision that limits development to valid existing rights and places a moratorium on new mining activity. Any future development will need to be carefully permitted and managed through Best Management Practices to ensure protection of the property’s Outstanding Universal Value.

Non-native species, from plants to fish to large mammals such as bison and elk also pose a management challenge. An increasing bison population in particular is emerging as a potentially important threat to the property.

Based on regional climate models, the Grand Canyon will be a warmer, drier place in the future. Precipitation levels are predicted to decline with warmer temperatures extending the dry season and reducing snowpack. A loss of moisture and snowpack can lead to an increase in wildfire activity. Increased wildfires release large amounts of greenhouse gases that increase carbon dioxide production into the atmosphere. Air pollution can also result from increasing temperatures. Climate change can cause erratic precipitation patterns that have the potential to increase the likelihood of flooding. As a result, these extreme events can lead to rockslides and wash-outs. Currently, the park monitors water resources and air quality and hopes to embark on geohazard monitoring in the near future.

Protection and management requirements

Designated by the U.S. Congress in 1919 as a national park, Grand Canyon is managed under the authority of the Organic Act of August 25, 1916 which established the United States National Park Service , and which directs park resources to managed “in such manner and by such means as will leave them unimpaired for the enjoyment of future generations.” In addition, the park has specific enabling legislation which provides broad congressional direction regarding the primary purposes of the park. Numerous other federal laws bring additional layers of protection to the park. Day to day management is directed by the Park Superintendent.

Management goals and objectives for the property have been developed through a General Management Plan, which has been supplemented with more site-specific planning exercises as well as numerous plans for specific issues and resources. In addition, the National Park Service has established Management Policies which provide broader direction for all National Park Service units, including Grand Canyon.

Park management plans for the property have identified a number of resource protection measures, such as environmental assessment processes, zoning, ecological integrity and visitor monitoring, and education programs to address pressures arising from issues both inside and outside the property. Specific measures have been introduced to address visitor capacity needs in sensitive resources areas of the Colorado River and wilderness areas of the park through management plans which structure visitor uses to best preserve park resources and values. Research, monitoring and management intervention are designed and implemented to mirror potential resource condition concerns. Active engagement with park partners, both within and outside park boundaries, assists in evaluating impacts to resources at a landscape scale. Examples include working directly with water managers in state and federal government agencies on flows from Glen Canyon Dam designed to protect and mitigate adverse impacts and improve the values within the property. Similarly, efforts continue to work with the gateway community of Tusayan to reduce potential developmental impacts upon the park so that compatible and sustainable developments are incorporated into future plans.

The national park works closely with other land and water management agencies in the larger region to protect shared resources. One example is the Southern Rockies Landscape Conservation Cooperative, a partnership of federal agencies which brings together science and resource management expertise to inform climate adaptation strategies and address other stressors within this ecological region.

Long-term protection and effective management of the park from potential threats require continued monitoring of resource conditions, such as through the NPS Inventory and Monitoring (I&M) program. The Southern Colorado Plateau I&M Network, of which Grand Canyon National Park is a part, has developed several “vital signs” to track a subset of physical, chemical and biological elements and processes selected to represent the overall health or condition of park resources. In Grand Canyon National Park, these vital signs include water quality, bird communities, springs, aquatic macroinvertebrates and upland vegetation and soils.

Management of the Outstanding Universal Value of the property is undertaken alongside close attention to the park’s important cultural heritage, which lies in its classic example of human adaptation to a severe climatic and physiographic environment. Unique cultural adaptations made by diverse cultural groups over millennia —such as establishing travel routes from river to rim, high elevation farming, and using varied microenvironments seasonally across the region—nurtured life in the rugged, remote Grand Canyon. These same adaptive strategies are found in neighboring tribes’ historic and present-day land use. This ancestral tie to the park and the land is manifest in the recognition of traditional association with at least 11 federally recognized American Indian tribes including the Havasupai, Hualapai, Hopi, Navajo, Southern Paiute, and Zuni. Park management routinely works with these tribes on various issues including access and accommodation to park resources, development of interpretive plans, formal consultation on planning documents and directives, and educational outreach.

Media

• Grand Canyon National Park (UNESCO/NHK)

News  (2)

• "Passport" booklet highlighting United States’ World Heritage sites published 16-Nov-2012
• Grand Canyon National Park Hosts U.S. World Heritage Fellow 22-Aug-2011

Links

• World Heritage in the United States
  
• Grand Canyon National Park (U.S. National Park Service)
  
• Protectedplanet.net