Question: The Tongue River Dam impounds a  tributary that is approximately how many miles long?

full_context: Document 1: Black Eagle Dam: Black Eagle Dam is a hydroelectric gravity weir dam located on the Missouri River in the city of Great Falls, Montana. The first dam on the site, built and opened in 1890, was a timber-and-rock crib dam. This structure was the first hydroelectric dam built in Montana and the first built on the Missouri River. The dam helped give the city of Great Falls the nickname "The Electric City." A second dam, built of concrete in 1926 and opened in 1927, replaced the first dam, which was not removed and lies submerged in the reservoir. Almost unchanged since 1926, the dam is 782 ft long and 34.5 ft high, and its powerhouse contains three turbines capable of generating seven megawatts (MW) of power each. The maximum power output of the dam is 18 MW. Montana Power Company built the second dam, PPL Corporation purchased it in 1997 and sold it to NorthWestern Corporation in 2014. The reservoir behind the dam has no official name, but was called the Long Pool for many years. The reservoir is about 2 mi long, and has a storage capacity of 1,710 acre.ft to 1,820 acre.ft of water.
Document 2: 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 3: Powder River (Wyoming and Montana): Powder River is a tributary of the Yellowstone River, approximately 375 mi long in northeastern Wyoming and southeastern Montana in the United States. It drains an area historically known as the Powder River Country on the high plains east of the Bighorn Mountains.
Document 4: Custer National Forest: Custer National Forest is located primarily in the south central part of the U.S. state of Montana but also has separate sections in northwestern South Dakota. With a total area of 1188130 acre , the forest comprises over 10 separate sections. While in the westernmost sections, Custer National Forest is a part of the Greater Yellowstone Ecosystem, the easternmost sections are a combination of forest "islands" and grasslands. A portion of the forest is also part of the Absaroka-Beartooth Wilderness and constitutes over a third of the wilderness land. South of Red Lodge, Montana, the Beartooth Highway (U.S. 212) passes through the forest en route to Yellowstone National Park.
Document 5: Red Rock River (Montana): The Red Rock River is a roughly 70 mi river in southwestern Montana in the United States. Its drainage basin covers over 1548 mi2 . Its furthest tributary, Hell Roaring Creek, originates in the Beaverhead National Forest within a few hundred meters of the North American Continental Divide and Montana-Idaho border near Brower's Spring, at an elevation of about 9100 ft . Brower's Spring is near the furthest headwaters of the Missouri River, one of the major watercourses of the central United States. The drainage flows north and west with its name changing to "Red Rock Creek" into the Red Rock Lakes in the middle of a wide grassy valley; the Red Rock River issues from the west side of Lower Red Rock Lake. It flows west, receiving many tributaries such as Peet Creek and Long Creek, widening into the Lima Reservoir and then passing through a canyon, which ends near Lima, Montana. From there, it flows northwest through a valley, passing Kidd and Red Rock, and into Clark Canyon Reservoir. Under the waters of the lake was once the confluence of the Red Rock and Horse Prairie Creek, forming the Beaverhead River, a tributary of the Jefferson River, in turn a headwater of the Missouri River.
Document 6: Yellowstone River: The Yellowstone River is a tributary of the Missouri River, approximately 692 mi long, in the western United States. Considered the principal tributary of the upper Missouri, the river and its tributaries drain a wide area stretching from the Rocky Mountains in the vicinity of the Yellowstone National Park across the mountains and high plains of southern Montana and northern Wyoming.
Document 7: Beartooth Mountains: The Beartooth Mountains are located in south central Montana and northwest Wyoming, U.S. and are part of the 900,000 acre (3,600 km) Absaroka-Beartooth Wilderness, within Custer, Gallatin and Shoshone National Forests. The Beartooths are the location of Granite Peak, which at 12,807 feet (3,904 m) is the highest point in the state of Montana. The mountains are just northeast of Yellowstone National Park and are part of the Greater Yellowstone Ecosystem. The mountains are traversed by road via the Beartooth Highway (U.S. 212) with the highest elevation at Beartooth Pass (10,947 ft, 3,345 m). The name of the mountain range is attributed to a rugged peak found in the range, Beartooth Peak, that has the appearance of a bear's tooth.
Document 8: Shoshone River: The Shoshone River is a 100 mi long river in northern Wyoming in the United States. Its headwaters are in the Absaroka Range in Shoshone National Forest. It ends when it runs into the Big Horn River near Lovell, Wyoming. Cities it runs near or through are Cody, Powell, Byron, and Lovell. Near Cody, it runs through a volcanically active region of fumaroles known as Colter's Hell. This contributed to the river being named on old maps of Wyoming as the "Stinking Water River".
Document 9: 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 10: 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 11: Bighorn Mountains: The Bighorn Mountains (Apsáalookěi: "Basawaxaawúua " or "Iisaxpúatahchee Isawaxaawúua ") are a mountain range in northern Wyoming and southern Montana in the United States, forming a northwest-trending spur from the Rocky Mountains extending approximately 200 miles (320 km) northward on the Great Plains. They are separated from the Absaroka Range, which lie on the main branch of the Rockies in western Wyoming, by the Bighorn Basin.
Document 12: 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 13: 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 14: Bighorn Basin: The Bighorn Basin is a plateau region and intermontane basin, approximately 100 miles (160 km) wide, in north-central Wyoming in the United States. It is bounded by the Absaroka Range on the west, the Bighorn Mountains on the east, and the Owl Creek Mountains and Bridger Mountains on the south. It is drained to the north by tributaries of the Bighorn River, which enters the basin from the south, through a gap between the Owl Creek and Bridger Mountains, as the Wind River, and becomes the Bighorn as it enters the basin. The region is semi-arid, receiving only 6–10 in (15–25 cm) of rain annually.
Document 15: Marias River: The Marias River is a tributary of the Missouri River, approximately 210 mi (338 km) long, in the U.S. state of Montana. It is formed in Glacier County, in northwestern Montana, by the confluence of the Cut Bank Creek and the Two Medicine River. It flows east, through Lake Elwell, formed by the Tiber Dam, then southeast, receiving the Teton River at Loma, 2 mi. (3.2 km) above its confluence with the Missouri.
ground_truth: 265