Question: The refuge for a historically significant herd of free-roaming Mustangs is close to what lake? 

full_context: Document 1: American Prairie Reserve: The American Prairie Reserve (APR) is an independent non-profit organization that has privately undertaken a project in northeastern Montana to create a wildlife conservation area of over three million contiguous acres through a combination of both private and public lands. APR’s goal is to acquire and manage approximately 500,000 private acres, which will serve to “glue together roughly three million acres of existing public land” to create a wildlife complex for conservation and public access. National Geographic has compared the project to the creation of an American Serengeti in a DVD it created about this region in 2010 (“American Serengeti”). <sup class="reference plainlinks nourlexpansion" id="ref_http://channel.nationalgeographic.com/episode/american-serengeti-3765/Overview">[#endnote_]</sup> In a global assessment prepared for the Temperate Grasslands Conservation Initiative (TGCI), scientists identified the area of APR in northeastern Montana as one of only four remaining areas in the world that are viable options for landscape-scale grasslands conservation. To promote tourism and encourage donations, APR has opened a high-end safari lodge and it continues to operate low-cost campgrounds, recruit volunteers and acquire land.
Document 2: Dryhead Country: Dryhead Country is a region in Carbon County and Big Horn County in southern Montana between Bighorn Canyon and the Pryor Mountains. The locale was named after the piles of dry bison skulls that accumulated at the base of a local buffalo jump. The Dryhead region starts near the Wyoming border in Bighorn Canyon National Recreation Area and extends northward into the Crow Indian Reservation. Dryhead Creek drains a portion of the area, falling eastwards into Bighorn Canyon. The semi-arid basin is one of the most remote areas in Montana. The area is sparsely populated with isolated ranches.
Document 3: Tongue River Dam: The Tongue River Dam (National ID # MT00002) is a dam in Big Horn County, Montana, a few miles north of the Wyoming state border. It impounds the Tongue River, creating the Tongue River Reservoir.
Document 4: Bighorn Canyon National Recreation Area: Bighorn Canyon National Recreation Area is a national park unit established by an act of Congress on October 15, 1966, following the construction of the Yellowtail Dam by the Bureau of Reclamation. It straddles the border between Wyoming and Montana. The dam, named after the famous Crow leader Robert Yellowtail, harnesses the waters of the Bighorn River by turning that variable watercourse into Bighorn Lake. The lake extends 71 mi through Wyoming and Montana, 55 mi of which lie within the national recreation area. About one third of the park unit is located on the Crow Indian Reservation. Nearly one-quarter of the Pryor Mountains Wild Horse Range lies within the Bighorn Canyon National Recreation Area.
Document 5: Tongue River (Montana): The Tongue River is a tributary of the Yellowstone River, approximately 265 mi (426 km) long, in the U.S. states of Wyoming and Montana. The Tongue rises in Wyoming in the Big Horn Mountains, flows through northern Wyoming and southeastern Montana and empties into the Yellowstone River at Miles City, Montana. Most of the course of the river is through the beautiful and varied landscapes of eastern Montana, including the Tongue River Canyon, the Tongue River breaks, the pine hills of southern Montana, and the buttes and grasslands that were formerly the home of vast migratory herds of American bison. The Tongue River watershed encompasses parts of the Cheyenne and Crow Reservations. The Headwaters lie on the Big Horn National Forest, and the watershed encompasses the Ashland Ranger District of the Custer National Forest.
Document 6: Pryor Mountain Mustang: The Pryor Mountain Mustang is a substrain of Mustang considered to be genetically unique and one of the few strains of horses verified by DNA analysis to be descended from the original Colonial Spanish Horses brought to the Americas by the Spanish. They live on the Pryor Mountains Wild Horse Range located in the Pryor Mountains of Montana and Wyoming in the United States, and are the only Mustang herd remaining in Montana. They are protected by the Wild and Free-Roaming Horses and Burros Act of 1971 (WFRHBA) and managed by the Bureau of Land Management (BLM), who has set the optimum herd number at 120 animals. Genetic studies have revealed that the herd exhibits a high degree of genetic diversity and a low degree of inbreeding, and BLM has acknowledged the genetic uniqueness of the herd. Pryor Mountain Mustangs are relatively small horses, exhibit a natural ambling gait, and domesticated Pryor Mountain Mustangs are known for their strength, sure-footedness and stamina.
Document 7: Mustang: The mustang is a free-roaming horse of the American west that first descended from horses brought to the Americas by the Spanish. Mustangs are often referred to as wild horses, but because they are descended from once-domesticated horses, they are properly defined as feral horses. The original mustangs were Colonial Spanish horses, but many other breeds and types of horses contributed to the modern mustang, resulting in varying phenotypes. In the 21st century, mustang herds vary in the degree to which they can be traced to original Iberian horses. Some contain a greater genetic mixture of ranch stock and more recent breed releases, while others are relatively unchanged from the original Iberian stock, most strongly represented in the most isolated populations.
Document 8: Pryor Mountains Wild Horse Range: The Pryor Mountains Wild Horse Range is a refuge for a historically significant herd of free-roaming Mustangs, feral horses colloquially called "wild horses", located in the Pryor Mountains of Montana and Wyoming in the United States. The range has an area of 39650 acre and was established in 1968 along the Montana–Wyoming border as the first protected refuge dedicated exclusively for Mustangs. It was the second feral horse refuge in the United States. About a quarter of the refuge lies within the Bighorn Canyon National Recreation Area. A group of federal agencies, led by the Bureau of Land Management, administers the range.
Document 9: Pathfinder Dam: Pathfinder Dam is a masonry dam, located on the North Platte River, approximately 47 mi southwest of Casper, Wyoming. It was originally constructed between 1905 and 1909 as part of the North Platte Project and has been modified several times since then. It is included on the National Register of Historic Places. Construction of the dam created Pathfinder Reservoir which provides water storage for 226000 acre of irrigation in Wyoming and Nebraska. The dam is named for General John Charles Fremont, who had explored the area in 1842 and was nicknamed the "Pathfinder of the West."
Document 10: National Bison Range Complex: The National Bison Range Complex includes four National Wildlife Refuges and the Northwest Montana Wetland Management District, and is located in the northwestern region of Montana in the northwestern United States.
Document 11: Establishment of Grand Teton National Park: The establishment of Grand Teton National Park took place over a period spanning more than 50 years. Located in the northwestern region of the U.S. state of Wyoming, Grand Teton National Park is 10 mi south of Yellowstone National Park which was established in 1872, when Wyoming, Idaho and Montana were still territories and the region was very sparsely settled. By the late 19th century, conservationists were working to provide further protection to surrounding regions, leading President Grover Cleveland to create the Teton Forest Reserve, which included a portion of northern Jackson Hole. By 1902, the reserve had been combined into the Yellowstone Forest Reserve, then was divided again in 1908 by President Theodore Roosevelt, establishing the Teton National Forest, which protected most of the Teton Range. By 1907, the U.S. Bureau of Reclamation had constructed a temporary dam at the Snake River outlet of Jackson Lake. This dam failed in 1910 and a new concrete Jackson Lake Dam replaced it by 1911. The dam was further enlarged in 1916, raising lake waters 39 ft as part of the Minidoka Project, designed to provide irrigation for agriculture in the state of Idaho. Though efforts to protect the Teton Range and Jackson Hole as part of an expanded Yellowstone National Park dated back to the late 19th century, proposals to construct more dams on some of the other lakes in Jackson Hole led Yellowstone National Park superintendent Horace Albright to block such efforts. Albright was originally an advocate of the expanded Yellowstone plan which was very unpopular with local residents. By the mid-1920s local sentiment had changed as a result of proposals for a new national park including only the Teton Range and six lakes at the base of the range. With the general agreement of prominent Jackson Hole residents to this plan, President Calvin Coolidge signed the executive order establishing the 96000 acre Grand Teton National Park on February 26, 1929.
Document 12: Rainbow Dam: Rainbow Dam is a hydroelectric dam on the Missouri River, 29 ft high and 1055 ft long, located six miles northeast of Great Falls in the U.S. state of Montana. The dam is named for the downstream Rainbow Falls, a 45 ft waterfall that is the third of the five Great Falls of the Missouri. Built in 1910, the dam furnishes water to an eight-unit hydroelectric plant with a capacity of 36 megawatts. As the dam's power plant is located over a half-mile downstream, the flow of water over Rainbow Falls and downstream Crooked Falls is significantly reduced during the dry season. The water from the penstocks re-enters the river a few hundred yards east of Crooked Falls. Montana Power Company acquired the dam when it was founded in 1912, PPL Corporation purchased it in 1997 and sold it to NorthWestern Corporation in 2014.
Document 13: Free-roaming horse management in North America: Management of free-roaming feral and semi-feral horses, (colloquially called "wild") on various public lands in North America is accomplished under the authority of law, either by the government of jurisdiction or efforts of private groups. In western Canada, management is a provincial matter, with several associations and societies helping to manage wild horses in British Columbia and Alberta. In Nova Scotia and various locations in the United States, management is under the jurisdiction of various federal agencies. The largest population of free-roaming horses are found in the Western United States, where most of them are protected under the Wild Free-Roaming Horses and Burros Act of 1971 (WFRH&BA), and their management is primarily undertaken by the Bureau of Land Management (BLM), but also by the U. S. Forest Service (USFS)
Document 14: UL Bend National Wildlife Refuge: UL Bend National Wildlife Refuge is a 56048 acre protected area that is located in central Montana, United States. The refuge, located at the extreme southernmost tip of Phillips County, is managed and bordered on three sides by the Charles M. Russell National Wildlife Refuge and the Fort Peck Reservoir on the Missouri River. The UL Bend Wilderness comprises almost half the refuge and provides a high level of protection to the most remote regions. This refuge is remote, requiring travel by gravel and dirt roads that can be difficult to navigate during inclement weather. A large species population of red fox, bald eagle, bighorn sheep, golden eagle, black bear, great horned owl, moose, burrowing owl, coyote, elk, swift fox, bobcat, pronghorn, mule deer, and cougar inhabit this refuge. Prairie dogs are abundant and are the primary food source for the black-footed ferret, which is listed as an endangered species. The Black-footed ferret has been reintroduced into the refuge after nearing extinction yet the sustainability of this relocated species is not yet known, and there are only 1,000 remaining in breeding compounds and perhaps 100 in the wild. Researchers in 2002 were only able to locate a total of 5 ferrets in the entire refuge.
Document 15: National Bison Range: The National Bison Range (NBR) is a National Wildlife Refuge located in western Montana established in 1908 to provide a sanctuary for the American bison. The NBR is one of the oldest National Wildlife Refuges in the United States. The size of the bison herd at the NBR is relatively small, numbering between 350 and 500 individuals. The initial herd of American bison was provided by organizations such as the American Bison Society, and today the refuge serves as the central point for bison research in the United States.
ground_truth: Bighorn Lake