are invasive species that can greatly impact fish species. Though the mussel species are not known to be in Wyoming, several surrounding regions have reported them. The New Zealand mud snail has been found in the Shoshone River east of the forest. Forest managers have established a preventative program to try to keep these species from entering forest waterways. Wilderness The forest contains four areas of pristine wilderness that have remained largely untouched by human activities such as mining, logging, and road and building construction. The four regions include the North Absaroka, Washakie, Fitzpatrick and Popo Agie Wildernesses. Additionally, a small portion of the Absaroka-Beartooth Wilderness extends into the extreme northwestern part of the forest, along the Montana border. In Shoshone National Forest, , constituting 56 percent of the forest is designated wilderness. The wilderness designation provides a much higher level of land protection and prohibits any alterations by man to the resource. The Wilderness Act of 1964 enhanced the protection status of remote and/or undeveloped land already contained within federally administered protected areas. Passage of the act ensured that no human improvements would take place aside from those already existing. The protected status in wilderness designated zones prohibits road and building construction, oil and mineral exploration or extraction, and logging, and also prohibits the use of motorized equipment, including even bicycles. The only manner in which people can enter wilderness areas is either on foot or horseback. Hunting and fishing are permitted in the wilderness, just as they are throughout the forest, provided those engaging in such activities have the proper licenses and permits. Fire ecology Fire Management officials in Shoshone National Forest recognize that forest fires are a natural part of the ecosystem; however, this was not always the case. 20th century fire fighting efforts, especially in the first half of that century, emphasized quickly extinguishing all fires, as fire was seen as completely detrimental to a forest. In 1935, fire management officials established the 10 am rule for all fires on federal lands, which recommended aggressive attack on fires and to have them controlled by 10 am, the day after they are first detected. This was intended to prevent fires from remaining active into the afternoon when the rising temperatures and more turbulent air caused fires to expand and become more erratic. However, this policy led to an increase in fuels because fires were often extinguished before