Yellowstone Handbook 2019

Complete Guide

brochure Yellowstone Handbook 2019 - Complete Guide

Yellowstone Resources and Issues Handbook. Published by the National Park Service (NPS).

Enemy at the Gates… Aquatic Invasive Species Yellowstone Resources and Issues Handbook 2019 U.S. Department of the Interior • National Park Service • Yellowstone National Park Yellowstone Park and Protection Act In 1872, the US Congress established Yellowstone National Park. The Yellowstone National Park Protection Act states, “the headwaters of the Yellowstone River…is hereby reserved and withdrawn from settlement, occupancy, or sale…and dedicated and set apart as a public park or pleasuring-ground for the benefit and enjoyment of the people.” The Organic Act of the National Park Service On August 25, 1916, President Woodrow Wilson signed the act creating the National Park Service, a federal bureau in the Department of the Interior. The Organic Act of the National Park Service states “the Service thus established shall promote and regulate the use of Federal areas known as national parks, monuments and reservations…by such means and measures as conform to the fundamental purpose of the said parks, monuments and reservations, which purpose is to conserve the scenery and the natural and historic objects and the wild life therein and to provide for the enjoyment of the same in such manner and by such means as will leave them unimpaired for the enjoyment of future generations.” ON THE COVER Madison River along the West Entrance Road. Photo taken June 17, 2014. NPS/Peaco. INSET PHOTOS clockwise from top right: Zebra mussels (Dreissena polymorpha). USFWS photo. Eurasian water milfoil (Myriophyllum spicatum); photo courtesy of Alison Fox, University of Florida. Bugwood.org. New Zealand mudsnail (Potamopyrgus antipodarum); ©Dr. Roy Anderson. http://www.habitas.org.uk/molluscireland Red-rimmed melania (Melanoides tuberculatus); ©2010 Hawaii Biological Survey, Bishop Museum. http://hbs.bishopmuseum.org/waipio Rainbow Trout infected with whirling disease parasite (Myxobolus cerebralis); ©2005 Sascha Hallett, Oregon State University. https://fishpathogens.net Yellowstone Resources and Issues Handbook 2019 An annual compendium of information about Yellowstone National Park U.S. Department of the Interior • National Park Service • Yellowstone National Park Yellowstone National Park, Wyoming 82190 Yellowstone National Park thanks Yellowstone Forever for support of this publication. Yellowstone Resources and Issues is produced and reviewed annually by Yellowstone National Park staff. Janine Waller, editor and designer Tami Blackford, managing editor Linda Young, executive editor Copyrights All material is in the public domain unless copyright is owned by a listed person or organization. All graphics are by the National Park Service unless credited otherwise. Suggested citation Yellowstone National Park. 2019. Yellowstone Resources and Issues Handbook: 2019. Yellowstone National Park, WY. Available free online at www.nps.gov/yell or for purchase through Yellowstone Forever. www.yellowstone.org ii Yellowstone Resources and Issues Handbook, 2019 Contents Welcome....................................................v Park Facts...................................................1 Frequently Asked Questions....................3 Canyon Village Area............................... 5 Fishing Bridge, Lake, and Bridge Bay.... 6 Madison and West Yellowstone Area.... 7 Mammoth Hot Springs Area.................. 8 Norris Area............................................... 9 Old Faithful Area.................................. 10 Tower–Roosevelt Area.......................... 11 West Thumb and Grant Village Area... 12 History of the Park..................................13 The Earliest Humans in Yellowstone......... 14 Increased Use......................................... 14 The Little Ice Age.................................. 15 Historic Tribes........................................ 16 The Tukudika: “Sheep Eaters”............. 16 European Americans Arrive....................... 16 Looking for Gold................................... 18 Expeditions Explore Yellowstone......... 18 Birth of a National Park............................. 19 Formative Years..................................... 21 The Army Arrives................................... 21 The National Park Service Begins......... 23 Boundary Adjustments......................... 23 World War II.......................................... 24 Mission 66.............................................. 24 Modern Management................................ 26 Involving Native Americans.................. 26 Complex Issues...................................... 27 A Living Legacy..................................... 27 Preserving Cultural Resources...............29 Archeology............................................ 29 Native American Affairs....................... 32 Historic Structures, Districts, and Cultural Landscapes............................................. 34 Collections............................................. 49 Greater Yellowstone Ecosystem............53 Heart of an Ecosystem................................ 53 Influence of Geology............................ 54 Air Quality............................................. 55 Soundscapes.......................................... 55 Water..................................................... 56 Cycles and Processes................................... 61 Winter Ecology...................................... 66 Climate Change..................................... 69 Changes in Yellowstone Climate.......... 71 Examining the Evidence....................... 76 Beyond Boundaries .................................... 82 Research in the Park............................. 84 Land Use................................................ 89 Wilderness............................................. 90 Winter Use ............................................ 93 Sustainable and Greening Practices... 100 Geology.................................................107 What Lies Beneath.............................. 107 At a Glance.......................................... 108 Geologic History of Yellowstone........ 109 Hydrothermal Systems........................ 115 Yellowstone Lake Geology................. 119 Earthquakes......................................... 122 Glaciers................................................. 124 Sedimentation and Erosion................ 126 Fossils................................................... 127 Life in Extreme Heat.............................131 About Microbes................................... 132 Thermophilic Bacteria......................... 134 Thermophilic Archaea ........................ 135 Thermophilic Eukarya......................... 136 Thermophilic Viruses........................... 138 Thermophilic Communities................ 139 Thermophiles in Time and Space....... 141 Vegetation.............................................143 Vegetation Communities.................... 143 Other Vegetation Communities......... 151 Wildflowers......................................... 152 Rare Plants........................................... 153 Invasive Plants..................................... 157 Restoring Native Plants....................... 159 Fire.........................................................161 Ignition................................................ 162 Fire Behavior........................................ 163 Frequency of Fire................................ 164 Consequences of Fire.......................... 164 Managing a Natural Process............... 167 History of Fire Management.............. 167 The 1988 Fires...................................... 168 Wildlife..................................................175 Mammals................................................... 176 Bears..................................................... 177 Bison..................................................... 189 Bighorn Sheep..................................... 201 Elk......................................................... 204 Moose.................................................. 209 Deer...................................................... 211 Pronghorn............................................ 213 Contents iii Wolves.................................................. 216 Coyotes................................................ 224 Red Foxes............................................. 226 Cougars................................................ 228 Canada Lynx........................................ 231 Bats....................................................... 233 Beavers................................................. 235 White-tailed Jackrabbits..................... 238 Wolverines........................................... 240 Other Small Mammals........................ 242 iv Yellowstone Resources and Issues Handbook, 2019 Birds........................................................... 248 Raptors................................................. 250 Wetland Birds...................................... 256 Songbirds and Woodpeckers.............. 261 Fish and Aquatic Species.......................... 265 Native Fish Species.............................. 268 Nonnative Fish Species........................ 275 Aquatic Invasive Species..................... 281 Incoming Threats................................ 284 Amphibians............................................... 286 Reptiles...................................................... 291 Yellowstone National Park, the world’s first national park, is named after the Yellowstone River. Welcome Yellowstone National Park is as wondrous as it is complex. The park has rich human and ecological stories that continue to unfold. When Yellowstone was established as the world’s first national park in 1872, it sparked an idea that influenced the creation of the National Park Service and the more than 400 sites it protects today across the United States. Yellowstone National Park also forms the core of the Greater Yellowstone Ecosystem. At 34,375 square miles, it is one of the largest, nearly intact temperate-zone ecosystems on Earth. The park continues to influence preservation and science, and we are pleased to share its stories with you. Many people have dedicated their lives and careers to studying Yellowstone and the park has a long history of research and public interest. The park hosts more than 150 researchers from various agencies, universities, and organizations each year. They produce hundreds of papers, manuscripts, books, and book chapters on their work annually—a volume of information that is difficult to absorb. This compendium is intended to help you understand the important concepts about Yellowstone’s many resources and contains information about the park’s history, natural and cultural resources, and issues. In addition to the references listed for each topic covered in this handbook, here are some interdisciplinary sources: • www.nps.gov/yell • Yellowstone Science, free from the Yellowstone Center for Resources, in the Yellowstone Research Library, or online at www.nps.gov/yellowstonescience. • The park newspaper distributed at entrance gates and visitor centers. • Site bulletins, published as needed, provide more detailed information on park topics such as trailside museums and the grand hotels. Free; available upon request from visitor centers. • Trail guides, available at all visitor centers. A $1 donation is requested. Second Century of Service On August 25, 2016, the National Park Service celebrated its 100th birthday. For a century the National Park Service has cared for and protected wildlife, land, waterways, accomplishments, lessons, and stories belonging to the citizens of the United States. And we are ready to connect with and create the next generation of park visitors, supporters, and advocates. Welcome v vi Yellowstone Resources and Issues Handbook, 2019 Park Facts Yellowstone National Park was established on March 1, 1872. Yellowstone is the world’s first national park. GEOGRAPHY 3,472 square miles (8,991 km2) 2,221,766 acres or 899,116 hectares. Note: No area figures have been scientifically verified. Efforts to confirm the park’s total area continue. 63 air miles north to south (102 km) 54 air miles east to west (87 km) 96% in Wyoming, 3% in Montana, 1% in Idaho Highest Point: 11,358 feet (3,462 m; Eagle Peak) Lowest Point: 5,282 feet (1,610 m; Reese Creek) Larger than Rhode Island and Delaware combined About 5% covered by water; 15% by grassland; and 80% by forests Precipitation Annual precipitation ranges from 10 inches (26 cm) at the north boundary to 80 inches (205 cm) in the southwest corner Temperature Average daily, at Mammoth: January: 9ºF (–13ºC) July: 80ºF (27ºC) Records: High: 99ºF (37ºC), 2002 (Mammoth) Low: –66ºF (–54ºC), 1933 (West Entrance, Riverside Station) Yellowstone Lake 131.7 square miles of surface area (341.1 km2) 141 miles of shoreline (227 km) 20 miles north to south (32 km) 14 miles east to west (22 km) Average depth: 138 feet (42 m) Maximum depth: 430 feet (131 m) GEOLOGY An active volcano One of the world’s largest calderas at 45 x 30 miles (72 x 48 km) 1,000­–3,000 earthquakes annually More than 10,000 hydrothermal features About 500 active geysers (more than half the world’s active geysers) About 290 waterfalls Tallest waterfall near a road: Lower Falls of the Yellowstone River at 308 feet (94 m) More than 720,000 museum items, including 30 historic vehicles Millions of archived documents More than 20,000 books (many rare), manuscripts, periodicals Fees: $43.9 Utilities & Agreements (Reimbursable): $5.4 11 visitor centers, museums, and contact stations 9 hotels/lodges (2,000+ hotel rooms/cabins) 7 NPS-operated campgrounds (450+ sites) 5 concession-operated campgrounds (1,700+ sites) More than 1,500 buildings 52 picnic areas, 1 marina, Distribution of Budget Park Support: 7% Includes human resources, contracting, budget and finance, partnerships, telecommunications, and information technology Facility Operations and Maintenance: 43% Includes utilities, roads, trails, structures, historic preservation coordination, construction management Park Protection: 13% Includes law enforcement, emergency medical services, search and rescue, entrance station operations, structural fire activities. Resource Stewardship: 9% Includes management operations and monitoring of natural and cultural resources, invasive species management, research coordination. Visitor Services: 28% Includes interpretation and education, and park concessions management. VEGETATION ROADS AND TRAILS VISITATION 9 species of conifers (more than 80% of forest is lodgepole pine) 1,000+ species of native flowering species (3 endemic) 225 species of invasive plants 186 species of lichens 5 park entrances 466 miles (750 km) of roads (310 miles [499 km] paved) More than 15 miles (24 km) of boardwalk, including 13 self-guiding trails Approximately 1,000 miles (1,609 km) of backcountry trails 92 trailheads 301 backcountry campsites The park recorded over 4.1 million visits in 2018; down 0.04% from 2017. The last time the park recorded fewer than 4 million annual recreational visits was in 2014, with 3.5 million visits. Detailed park visitation information is available at https://irma.nps.gov/Stats/ WILDLIFE 67 species of mammals, including: 7 species of native ungulates 2 species of bears 285 species of birds (150 nesting) 16 species of fish (5 nonnative) More than 7 aquatic nuisance species (3 having significant detrimental effect) 5 species of amphibians 6 species of reptiles 2 threatened species: Canada lynx, grizzly bears CULTURAL RESOURCES 26 associated Native American tribes More than 1,800 known archeological sites More than 300 ethnographic resources (animals, plants, sites) 25 sites, landmarks, and districts on the National Register of Historic Places; many more eligible for listing 1 National Historic Trail More than 900 historic buildings EMPLOYEES National Park Service Permanent (382 total) Full time, year-round: 177 Career Seasonal: 202 Part time: 3 Term (variable duration): 4 Seasonal: 370 Concessioners About 3,200 people work for concessioners at summer peak. FACILITIES BUDGET Fiscal Year 2018 (in millions) Total: $118.7 Federal Funding: Congressional Annual Appropriations: Operations and staff (base): $39.9 Wildland Fire: $1.2 Other Appropriations: $26.6 Other Funding: Donations and Grants: $1.7 Top 10 Visitation Years 1. 2016 4,257,177 2. 2017 4,116,524 3. 2018 4,114,999 4. 2015 4,097,710 5. 2010 3,640,184 6. 2014 3,513,484 7. 2012 3,447,727 8. 2011 3,394,321 9. 2009 3,295,187 10. 2013 3,188,030 Park Facts 1 Yellowstone National Park M T North Entrance Ï Yellowsto Mammoth Ï Gall atin River ne ÏNortheast Ri v Entrance er W Y Tower Junction Ï Ï Tower Fall ÏLamar La r ma # Ï Norris iv er n Rive so ÏCanyon Gi b b o Madison n wsto llo Ye Madi r Ï R ne Ri Ï v er Lake Fir eh ole River West Entrance I D er Riv Mount Washburn 10,243 ft 3,122m Old Faithful Bridge Bay Ï Ï ÏFishing Bridge Ï Ï Ï East Entrance Yellowstone Lake West ThumbÏ Shoshone Lake Ï Grant Ye Riv er ch ler Heart Lake r Be Sn Bechler Ï # Eagle Peak 11,358 ft 3,462 m e Riv stone llow Lewis Lake ak eR iv e r lls Fa Ri ver Ï South Entrance John D. Rockefeller, Jr. Memorial Parkway 0 0 Ï Caldera Continental Divide Rivers Roads 10 Kilometers 10 Miles Developed Areas Grand Teton National Park 2 Yellowstone Resources and Issues Handbook, 2019 Lakes # Summits State Boundary NPS Boundary North Á Frequently Asked Questions How did Yellowstone get its name? Yellowstone National Park is named after the Yellowstone River, the major river running through the park. According to FrenchCanadian trappers in the 1800s, they asked the name of the river from the Minnetaree tribe, who live in what is now eastern Montana. They responded “Mi tse a-da-zi,” which translates as “Yellow Stone River” The trappers translated this into French and in 1797, explorer-geographer David Thompson first used the English translation. Lewis and Clark called the Yellowstone River by the French and English forms. Subsequent use formalized the name “Yellowstone.” Is Yellowstone the largest national park? No. More than half of Alaska’s national park units are larger, including Wrangell–St. Elias National Park and Preserve, which is the largest unit (13 million acres) in the National Park System. Until 1994, Yellowstone (at 2.2 million acres) was the largest national park in the contiguous United States. That year Death Valley National Monument was expanded and became a national park—it has more than 3 million acres. Is Yellowstone the most visited national park? No. Yellowstone is in the top five national parks for number of recreational visits. Great Smoky Mountains National Park has the most—more than 11.4 million in 2018. The Grand Canyon (6.3 million) Rocky Mountain (4.59 Million), and Zion (4.3 million) also received more recreational visits than Yellowstone (4.15 million) in 2018. Visit the website https://irma.nps.gov/Stats/ to find out more details about how many visitors come to our national parks. What is the difference between a national park and a national forest? National parks are administered by the Department of the Interior and national forests by the Department of Agriculture. The National Park Service is mandated to preserve resources unimpaired, while the Forest Service is mandated to wisely manage resources for many sustainable uses. Six national forests surround Yellowstone National Park. How many rangers work in Yellowstone? Approximately 750 people work for the National Park Service during the peak summer season. Approximately 190 are permanent, year-round employees. Park rangers work in education, resource management, law enforcement, emergency medical services, and backcountry operations. Other employees specialize in research, maintenance, management, administration, trail maintenance, fire management, and fee collection. How do you become a park ranger? Park rangers have a variety of different duties. Most have a bachelor’s degree in a related field, and some may have advanced degrees or additional special training in law enforcement, education, or wildlife management. Park Rangers are federal employees hired by individual parks. Many National Park Service employees begin their careers as volunteers or as seasonal employees. Hiring is very competitive and is conducted through the Office of Personnel Management website: usajobs.gov. Approximately 773 people work for the National Park Service in Yellowstone National Park during the peak summer season. Can we swim in rivers and lakes? Swimming is not recommended, and is occasionally prohibited, because most lakes and streams are dangerously cold. Firehole Canyon, near Madison Junction, has a swimming area popular in summer. Soaking in thermal features is illegal. The area known as the Boiling River, north of Mammoth Hot Springs, allows soaking in the Gardner River near thermal outflow, but not in the feature itself. Soaking is allowed during daylight hours only and at your own risk. What is the highest peak in the park? Eagle Peak in the southeastern part of Yellowstone is the highest at 11,358 feet (3,462 m). Why is Yellowstone called a biosphere reserve and a world heritage site? The United Nations designated Yellowstone National Park as a biosphere reserve and a world heritage site in recognition of the worldwide significance of its natural and cultural resources. These designations have nothing to do with how Yellowstone is managed—the United Nations has no authority to dictate federal land management decisions in the United States—nor do they change the fact that Yellowstone is under the legal authority of the United States of America. The October 26, 1976, United Nations designation of Yellowstone as a biosphere reserve stated: Yellowstone National Park is recognized as part of the international network of biosphere reserves. This network of protected samples of the world’s major ecosystem types is devoted to conservation of nature and scientific research in the service of man. It provides a standard against which the effect of man’s impact on the environment can be measured. Frequently Asked Questions 3 Divide, it eventually reaches the Pacific Ocean. When it falls on the east side of the Divide, it eventually reaches the Atlantic Ocean. In Yellowstone (as elsewhere), this ridgeline is not straight. You cross the Continental Divide three times between the South Entrance and the Old Faithful area. Craig Pass is the highest crossing, at 8,262 feet (2,518 m). The September 8, 1978, United Nations designation of Yellowstone as a world heritage site, requested by US President Richard Nixon and Congress, stated: Through the collective recognition of the community of nations … Yellowstone National Park has been designated as a World Heritage Site and joins a select list of protected areas around the world whose outstanding natural and cultural resources form the common inheritance of all mankind. How did Mt. Washburn form? At 10,243 feet (3,122 m), this peak can be seen from many locations in the park. It is a remnant of an extinct volcano from the Absaroka Volcanics of about 50 million years ago. The volcano was literally cut in half by a volcanic eruption 640,000 years ago. Only the northern part of the original volcano is still visible. To find out more, visit www.unesco.org/mab. What is the Continental Divide? Think of the Continental Divide as the crest of the continent. Theoretically, when precipitation falls on the west side of the C A N A D A Glacier NP Williston ÀFCA ! Kalispell ! Fort Union Trading Post NHS ri River Missou ! Great ÀGTF Theodore Roosevelt NP and Wilderness Falls M O N T A N A À!Missoula ! Dickinson ! Lewistown MSO Helena !À Miles City HLN ND ! Ri ve r Grant-Kohrs Ranch NHS ÀButte ! BIL BTM BillingsÀ BZN À ! ! er ! Yellow sto ne ! Gardiner ! West Yellowstone À Craters of the Moon NM and Wilderness Rexburg ! À! Sheridan ! ! COD À Idaho Falls ÀJAC ! Jackson À ! Pocatello PIH Devil’s Tower NM Gillette ! Cody ! RAP Rapid City ! À Mount Rushmore NM John D. Rockefeller, Jr. Mem. Pkwy Grand Teton NP IDA SD Red Lodge Cooke City ! Yellowstone National Park WYS I D A H O e Little Bighorn Battlefield NM Bighorn Canyon NRA Livingston R iv Bozeman Big Hole Battlefield Yello w n sto Jewel Cave NM Wind Cave NP W Y O M I N G North Á Roads CPR À Airports Casper À State Boundaries Rivers and Lakes Continental Divide National Park Service ! The National Park Service manages approximately 83 million acres in 50 states, the Virgin Islands, Puerto Rico, Guam, and American Samoa. Here are the sites near Yellowstone. 4 Yellowstone Resources and Issues Handbook, 2019 Hayden Valley, shown here, is one of the best places in the park to view a wide variety of large mammals. Canyon Village Area Notable Areas and Structures • Artist Point presence or absence of water in the individual iron compounds and hydration of minerals in the rock. Most of the yellows in the canyon result from iron and sulfur in the rock. • Grand Canyon of the Yellowstone River • Mount Washburn How much water goes over the falls? • Hayden Valley The volume varies from 63,500 gallons (240,000 l) per second at peak runoff to 5,000 gallons (18,900 l) per second in the late fall. How tall are the falls? Upper Falls: 109 feet (33 m).; Lower Falls: 308 feet (94 m). How big is the Grand Canyon of the Yellowstone? This huge canyon is roughly 20 miles (32 km) long, more than 1,000 feet (305 m) deep, and 1,500–4,000 feet (457–1,219 m) wide at various points. How did the canyon form? Scientists continue to develop theories about its formation. After the Yellowstone Caldera eruption, 640,000 years ago, lava flows and volcanic tuffs buried the canyon area; but hydrothermal gases and hot water weakened the rock. The river eroded this rock, carving a canyon in the Yellowstone River beginning at Tower Fall and heading upstream to Lower Falls. Where can I see the canyon and falls? North Rim Drive: Walkways at Lookout Point and Brink of the Lower Falls lead to views of both waterfalls. The longest stretch of accessible trail can be accessed from parking lots at Lookout or Grand View. You can also see the Lower Falls from Red Rock and Inspiration points. South Rim Drive: See the Lower Falls at Artist Point, from Uncle Tom’s Trail, and from a few places along the South Rim Trail; see the Upper Falls from two viewpoints at Uncle Tom’s Point. Visit Brink of Upper Falls from a viewing area just off the Grand Loop Road south of Canyon Junction, between the entrances to North and South Rim drives. Where can I see both falls at once? The canyon bends between the Upper and Lower falls, so there is no location where they can be seen at the same time. What causes the different colors in the canyon? You could say the canyon is “rusting.” The colors are caused by oxidation of iron compounds in the rhyolite rock, which has been hydrothermally altered (“cooked”). The colors indicate the What causes the Lower Falls’ green stripe? The natural color of the water. A notch in the lip of the brink makes the water deeper and keeps it from mixing with air and becoming frothy, so the color is visible as it goes over the edge. Who was “Uncle Tom”? “Uncle Tom” Richardson was an early concessioner in the canyon area. From 1898–1905, he guided visitors to the canyon floor down a steep trail using rope ladders. Today the trail descends partway into the canyon via steep steel steps. Can I get to the bottom of the canyon? Only one trail in this area leads to the bottom of the canyon— Seven Mile Hole Trail, a strenuous, steep round trip of 10.2 miles. Is Artist Point the location where Thomas Moran painted his Grand Canyon of the Yellowstone? No, it is thought that some sketches were made from Moran Point and that a compilation of canyon views were incorporated into the painting. What animals can I see in this area? Inside the canyon, look for osprey soaring over the river or perched on their five-foot (1.5 m) diameter nests. They nest here from late April until early September. Also look for ravens and swallows. During July, a variety of butterflies feast on the abundant flowers in the meadows. Hayden Valley, approximately five miles (8 km) south of Canyon Junction, is one of the best places in the park to view a wide variety of large mammals. Grizzly bears and black bears are often seen in the spring and early summer. Large herds of bison may be seen in the spring, early summer, and during the rut in August. Coyotes can almost always be seen in the valley; wolves are often seen as well. Mount Washburn is an excellent place for viewing wildlife. Bighorn sheep and marmots can be seen on its slopes in the summer. Elk and bison frequent the valley north of the mountain. Frequently Asked Questions 5 Fishing Bridge, located on the Yellowstone River at Yellowstone Lake, is a good place to watch trout, though fishing is now prohibited from the bridge. Fishing Bridge, Lake, and Bridge Bay Historic Areas and Structures • Fishing Bridge Why can’t we fish from Fishing Bridge? • Fishing Bridge Visitor Center • Lake Historic District Overfishing for cutthroat trout here contributed to their decline in the lake. The trout also spawn here. For these reasons, fishing is prohibited from the bridge. It’s still a good place to watch trout. • Lake Fish Hatchery Historic District How cold is Yellowstone Lake? • Lake Hotel • Bridge Bay Marina Historic District • East Entrance Historic Road During late summer, Yellowstone Lake becomes thermally stratified with several water layers having different temperatures. The topmost layer rarely exceeds 66°F (18.8°C), and the lower layers are much colder. Because of the extremely cold water, survival time for anyone in the lake is estimated to be only 20 to 30 minutes. In winter, ice thickness on Yellowstone Lake varies from a few inches to more than two feet with many feet of snow on top of the ice. Where does the Yellowstone River begin? Where does it end? It begins on the slopes of Younts Peak in the Absaroka Mountains southeast of the park flows 671 miles (1080 km) to the Missouri River near the Montana–North Dakota border. Its waters then travel to the Mississippi River and into the Atlantic Ocean at the Gulf of Mexico. It is the longest undammed river in the contiguous United States. How big is Yellowstone Lake? How deep? Is it natural? The lake is natural and has 131.7 square miles (341.1 km2)of surface area and 141 miles (227 km) of shoreline; it is 20 miles (32 km) long by 14 miles (22 km) wide. Its deepest spot is about 430 feet (131 m); its average depth is 138 feet (42 m). The lake’s basin has an estimated capacity of 12,095,264 acre-feet (1.5x1013 l) of water. Because its annual outflow is about 1,100,000 acre-feet (1.3x1012 l), the lake’s water is completely replaced only about every eight to ten years. Since 1952, the annual water level fluctuation has been less than six feet (2 m). It is the largest lake at high elevation (above 7,000 ft/2134 m) in North America. How did Yellowstone Lake form? The lake’s main basin is part of the Yellowstone Caldera, which was formed 640,000 years ago. West Thumb was formed by a later, smaller eruption. The arms of the lake were formed by uplift along fault lines and sculpting by glaciers. The lake drains north at Fishing Bridge. Some scientists consider LeHardy’s Rapids to be the geologic northern boundary of the lake because the periodic rise and fall of that site appears to control lake outflow. What happened to the old campground at Fishing Bridge? The National Park Service campground was located where bears came to fish, and many

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