1.         Yellowstone National Park (United States of America) (N 28)

Year of inscription on the World Heritage List  1978

Criteria  (vii)(viii)(ix)(x)

Year(s) of inscription on the List of World Heritage in Danger    1995-2003

Previous Committee Decisions  see page https://whc.unesco.org/en/list/28/documents/

International Assistance

Requests approved: 0
Total amount approved: USD 0
For details, see page https://whc.unesco.org/en/list/28/assistance/

UNESCO Extra-budgetary Funds


Previous monitoring missions

1995: World Heritage Centre / IUCN mission 

Factors affecting the property identified in previous reports

a) Mining;

b) Wildlife management: bison and cut-throat trout;

c) Invasive alien species;

d) Water quality;

e) Road construction;

f) Snow mobile impact on noise and air quality;

g) Visitor numbers. 

Illustrative material  see page https://whc.unesco.org/en/list/28/

Conservation issues presented to the World Heritage Committee in 2008

In its report submitted on 30 January 2008, the State Party documented progress in addressing the threats already identified in 1995 which led to its inclusion in the List of World Heritage in Danger.


The State Party reported on progress in carrying out the New World Mining District Response and Restoration project. Measures have been taken to reduce mine water discharge, and discussions are underway for long-term monitoring and maintenance of the waste repository.


The State Party noted that the pathogen agent Brucella abortus poses an economic threat to the livestock industry in the region neighbouring the property. As a result, some of the bison migrating out of the park are killed. Bison are managed through the 2000 joint bison management plan (BMP). The State Party reported that Bison numbers had been maintained between 3,000 and 5,000 over the last 5 years. The State Party is also conducting research to determine how to eliminate brucellossis while maintaining wild and free roaming herds in the Greater Yellowstone Area.

Though the State Party did not provide a copy of the BMP or data on bison migration or numbers killed for disease prevention, NGOs, media and experts report that the evidence for the role of bison in transmitting Brucella abortus is not definitive. There are no confirmed cases of brucellosis transmission from bison to cattle under natural conditions and reports note that other ungulates also carry the disease but are managed differently. In addition, a number of independent experts have noted that the BMP needs to be reviewed to adapt to changed circumstances. For example, cattle no longer graze in a number of areas which could allow wild bison more room to roam on their native range.

There are also increased opportunities to plan and manage corridors to support migration, such as through the Yellowstone Yuken Corridor, and increased support from local communities towards conservation efforts. At the time of inscription of the property, the forest lands surrounding it were considered to add value in protecting the integrity of the landscape required for wildlife, in particular bison, to migrate. Changing land use and competition with development and cattle farmers has affected the freedom of movement of the bison changing its natural behaviour and reducing the natural processes for which the property was inscribed. Thus increased attention to the implementation of the BMP is justifiable due to its strong link with the outstanding universal value and integrity of the property.

The World Heritage Centre and IUCN recommend that a detailed disease transmission risk analysis, incorporating new scientific information in particular related to the genetically distinct bison subpopulations and the changing risks for disease transmission, be conducted for all ungulates which should take part in parallel with a review of the BMP. Acknowledging that managing the bison population as migratory species is a complex and medium-long term task, it is noted that the BMP should be consistent with the protection and maintenance of the outstanding universal value and integrity of the property. Funding should support migration corridors outside the property.

Cutthroat Trout

The non-native lake trout continues to pose a grave threat to the rare and endemic cutthroat trout and 42 other native birds and mammals that depend on this species, to varying extents, for their survival. The State Party reported that despite intensive efforts to remove the invasive lake trout, research suggests that the population of lake trout is continuing to expand. The State Party believes that improved removal methods are slowing the rate of expansion of the lake trout. The consequences for the cutthroat trout are that only modest improvements since 2006 have been observed in spawning-age size classes, first-time spawning fish and fish stream counts. Media reports suggest that low water levels in Yellowstone Lake caused by drought and whirling disease are further putting stress on cutthroat trout populations.

Water quality

Water quality in the property has been threatened by old, outdated waste water treatment plants, lift stations and underground lines, and old single wall fuel tanks. This inadequate waste water and fuel infrastructure lead to accidental overflows, ruptures and spills affecting soil, ground and surface water and degradation of the land in some areas of the property. These threats have been partially addressed by a USD 22 million fund, but a significant amount of outstanding investment is still required.


The roads in the property were not designed for the very high visitor pressures which currently exist. This has contributed to resource degradation. Investment and reconstruction is underway and is due to continue into the 2020s. The State Party reported that construction processes comply with the measures set out by the National Environmental Policy Act.

Visitor use impact

Winter visitation continues to be particularly controversial due to the use of snowmobiles, banned during 2000-2003, but allowed since. The final Environmental Impact Statement for the winter use plan proposed reducing snowmobile numbers from 720 to a maximum of 540 snowmobiles per day. However, in the opinion of experts, this figure should be further reduced to 250 snowmobiles per day to limit noise and atmospheric pollution affecting the values and integrity of the property, particularly in relation to criterion (vii), as well as to increase the quality of visitor experiences. Several solid waste management initiatives are underway to improve the sustainability of visitor use by encouraging recycling and composting of organic materials. Partnerships have been established to promote alternative fuel for transportation and reduced emissions transport such as through the use of hybrid vehicles. Visitation in 2007 equalled the former peak in 1995 and media reports noted that there were 3.15 million visitors to Yellowstone in 2007 which represents a 9.8% increase since 2006. Visitation reached its highest in July with an average in 2007 of 26,542 visitors per day.

Emerging concerns and threats

A number of experts, NGOs and media reports noted increasing human-wildlife conflict, and the loss of whitebark pine due to multiple factors including the bark pine beetle, and warming weather trends. Whitebark pine is important for grizzly bears and helps to regulate water flow during spring snow melt. The Greater Yellowstone area is also facing increasing development pressures causing landscape fragmentation, which reduces opportunities for the property to cope with predicted effects from climate change and maintain traditional migration routes for species, including bison.

Management and policy

The World Heritage Centre and IUCN note that the property is being managed through a number of detailed and targeted plans on specific issues. Whilst implementation of these specific plans is welcome, they consider that a general management plan for the properties would help to ensure that management is carried out in a cohesive and effective manner to protect its outstanding universal values and integrity. Updating the 1973 plan would provide an opportunity to assess changes and align the various policies and management affecting migratory species in particular. It would also help in assessing risk associated with the potential impacts from climate change on the integrity of this property thus helping to identify and further implement climate change mitigation and adaptation measures.

Analysis and Conclusions of the World Heritage Centre and IUCN


Decision Adopted: 32 COM 7B.29

The World Heritage Committee,

1. Having examined Document WHC-08/32.COM/7B,

2. Recalling Decision 30 COM 7B.28, adopted at its 30th session (Vilnius, 2006),

3. Acknowledges progress in implementing the New World Mining District Response and Restoration project, restoring the roads within the guidelines of the National Environment Policy Act, and in implementing water quality improvement measures;

4. Requests the State Party to continue to address the threats identified in this and previous reports in particular:

a) accelerate the adaptive management changes under the Bison management plan, including:

i) carry out a risk analysis for disease transmission from bison to cattle and include other ungulates by including a review of scientific knowledge on disease transmission, bison behaviour and genetics, and seasonal factors;

ii) consider changing cattle management practices so that bison can migrate naturally, and;

iii) promote and enhance stakeholders' participation and accountability and transparency on the implementation of this plan.

b) increase efforts to understand the causes for the slow recovery of the cutthroat trout;

i) carry out a scientific review of the programme to remove the lake trout invasive species;

ii) investigate the effects of reduced lake levels and drought on the cutthroat trout and consider the potential role of climate change in further affecting the recovery of this species;

c) assess the risk to grizzly bears from declining whitebark pine and investigate the severity of bark pine beetle infestation and the role of changing temperatures;

5. Notes the continued pressures from high visitor use and calls on the State Party to:

a) implement a sustainability programme to reduce the impacts of visitation and parks operations to ensure that the Outstanding Universal Value of the property can be transmitted to future generations;

b) continue assessing visitor numbers and the effects of visitor use on the Outstanding Universal Value of the property;

c) continue assessing winter visitation and the effects from snowmobiles;

6. Requests the State Party to invite a joint World Heritage Centre / IUCN Reactive Monitoring mission in 2011 to review progress in implementing the recommendations of the World Heritage Committee;

7. Also requests the State Party to submit to the World Heritage Centre, by 1 February 2010, a detailed report on the state of conservation of the property and on progress made in addressing the different issues above, for examination by the World Heritage Committee at its 34th session in 2010.