Question: What is the source of the river from which the Imperial Valley gets almost all of its water?

full_context: Document 1: Geography of the United States: West of the Rocky Mountains lies the Intermontane Plateaus (also known as the Intermountain West), a large, arid desert lying between the Rockies and the Cascades and Sierra Nevada ranges. The large southern portion, known as the Great Basin, consists of salt flats, drainage basins, and many small north-south mountain ranges. The Southwest is predominantly a low-lying desert region. A portion known as the Colorado Plateau, centered around the Four Corners region, is considered to have some of the most spectacular scenery in the world. It is accentuated in such national parks as Grand Canyon, Arches, Mesa Verde National Park and Bryce Canyon, among others. Other smaller Intermontane areas include the Columbia Plateau covering eastern Washington, western Idaho and northeast Oregon and the Snake River Plain in Southern Idaho.
Document 2: Imperial Valley: The Imperial Valley extends southward for 50 miles (80 km) from the southern end of the Salton Sea into Mexico. Part of a trough stretching from the Coachella Valley to the Gulf of California, it is almost entirely below sea level -- 235 feet (72 m) below at the edge of the Salton Sea. Its hot desert climate is characterized by daily temperature extremes. It was once part of the Gulf of California, from which it was cut off by the dam - like deposits of the Colorado River Delta Fan as it carved out the Grand Canyon. Bordered by sand dunes and barren mountains, it was uninhabited until 1901, when the Imperial Canal was opened and diverted Colorado River water into the valley through Mexico. Flood - waters in 1905 -- 07 destroyed the irrigation channels and created the Salton Sea now filled by the New River and irrigation run - off. The rivers in the southern part of the Salton Sea river basin flow south to north.
Document 3: Water in California: The Colorado River originates more than 1,000 miles (1,600 km) from California in the Rocky Mountains of Colorado and Wyoming and forms the state's southeastern border in the Mojave Desert. Unlike the other California watersheds, essentially all of the water flowing in the Colorado originates outside the state. The Colorado is a critical source of irrigation and urban water for southern California, providing between 55 and 65 percent of the total supply.
Document 4: Red Desert (Wyoming): The Red Desert is a high altitude desert and sagebrush steppe located in south central Wyoming, comprising approximately 9,320 square miles (24,000 km). Among the natural features in the Red Desert region are the Great Divide Basin, a unique endorheic drainage basin formed by a division in the Continental Divide, and the Killpecker Sand Dunes, the largest living dune system in the United States. In the 19th century, the Oregon, California and Mormon Trails crossed the Continental Divide at South Pass, just north of the Red Desert. Today, busy Interstate 80 bisects the desert's southern region while gas field roads cross the desert.
Document 5: Colorado River (Texas): Colorado River Texas The Colorado River in Austin, as seen from Mount Bonnell. Country United States State Texas Source - location Dawson County - elevation 3,280 ft (1,000 m) - coordinates 32 ° 40 ′ 47 ''N 101 ° 43 ′ 51'' W ﻿ / ﻿ 32.67972 ° N 101.73083 ° W ﻿ / 32.67972; - 101.73083 Mouth Matagorda Bay - location Gulf of Mexico, at Matagorda County, Texas - elevation 0 ft (0 m) - coordinates 28 ° 35 ′ 41 ''N 95 ° 58 ′ 59'' W ﻿ / ﻿ 28.59472 ° N 95.98306 ° W ﻿ / 28.59472; - 95.98306 Coordinates: 28 ° 35 ′ 41 ''N 95 ° 58 ′ 59'' W ﻿ / ﻿ 28.59472 ° N 95.98306 ° W ﻿ / 28.59472; - 95.98306 Length 862 mi (1,387 km) Basin 39,900 sq mi (103,341 km) Discharge for Bay City - average 2,609 cu ft / s (74 m / s) - max 84,100 cu ft / s (2,381 m / s) - min 0 cu ft / s (0 m / s) Map of the Colorado River and associated watershed
Document 6: Grand Canyon: The Grand Canyon (Hopi: Ongtupqa; Yavapai: Wi: kaʼi: la, Navajo: Tsékooh Hatsoh, Spanish: Gran Cañón) is a steep - sided canyon carved by the Colorado River in Arizona, United States. The Grand Canyon is 277 miles (446 km) long, up to 18 miles (29 km) wide and attains a depth of over a mile (6,093 feet or 1,857 meters).
Document 7: Colorado River: Colorado River The Colorado River at Horseshoe Bend, Arizona, a few miles below Glen Canyon Dam Countries United States, Mexico States Colorado, Utah, Arizona, Nevada, California, Baja California, Sonora Tributaries - left Fraser River, Blue River, Eagle River, Roaring Fork River, Gunnison River, Dolores River, San Juan River, Little Colorado River, Bill Williams River, Gila River - right Green River, Dirty Devil River, Escalante River, Kanab River, Virgin River, Hardy River Cities Glenwood Springs, CO, Grand Junction, CO, Moab, UT, Page, AZ, Bullhead City, AZ, Lake Havasu City, AZ, Yuma, AZ, San Luis Rio Colorado, SON Source La Poudre Pass - location Rocky Mountains, Colorado, United States - elevation 10,184 ft (3,104 m) - coordinates 40 ° 28 ′ 20 ''N 105 ° 49 ′ 34'' W ﻿ / ﻿ 40.47222 ° N 105.82611 ° W ﻿ / 40.47222; - 105.82611 Mouth Gulf of California - location Colorado River Delta, Baja California -- Sonora, Mexico - elevation 0 ft (0 m) - coordinates 31 ° 54 ′ 00 ''N 114 ° 57 ′ 03'' W ﻿ / ﻿ 31.90000 ° N 114.95083 ° W ﻿ / 31.90000; - 114.95083 Coordinates: 31 ° 54 ′ 00 ''N 114 ° 57 ′ 03'' W ﻿ / ﻿ 31.90000 ° N 114.95083 ° W ﻿ / 31.90000; - 114.95083 Length 1,450 mi (2,334 km) Basin 246,000 sq mi (637,137 km) Discharge for mouth (average virgin flow), max and min at Topock, AZ, 300 mi (480 km) from the mouth - average 22,500 cu ft / s (637 m / s) - max 384,000 cu ft / s (10,900 m / s) - min 422 cu ft / s (12 m / s) Map of the Colorado River basin Wikimedia Commons: Colorado River
Document 8: Mexico City: Originally much of the valley laid beneath the waters of Lake Texcoco, a system of interconnected salt and freshwater lakes. The Aztecs built dikes to separate the fresh water used to raise crops in chinampas and to prevent recurrent floods. These dikes were destroyed during the siege of Tenochtitlan, and during colonial times the Spanish regularly drained the lake to prevent floods. Only a small section of the original lake remains, located outside the Federal District, in the municipality of Atenco, State of Mexico.
Document 9: Southern California: To the east is the Colorado Desert and the Colorado River at the border with Arizona, and the Mojave Desert at the border with the state of Nevada. To the south is the Mexico–United States border.
Document 10: Dolores River: The Dolores River is a tributary of the Colorado River, approximately long, in the U.S. states of Colorado and Utah. The river drains a rugged and arid region of the Colorado Plateau west of the San Juan Mountains. Its name derives from the Spanish "El Rio de Nuestra Señora de Dolores", River of Our Lady of Sorrows. The river was explored and possibly named by Juan Maria Antonio Rivera during a 1765 expedition from Santa Fe.
Document 11: Israel: The Jordan River runs along the Jordan Rift Valley, from Mount Hermon through the Hulah Valley and the Sea of Galilee to the Dead Sea, the lowest point on the surface of the Earth. Further south is the Arabah, ending with the Gulf of Eilat, part of the Red Sea. Unique to Israel and the Sinai Peninsula are makhteshim, or erosion cirques. The largest makhtesh in the world is Ramon Crater in the Negev, which measures 40 by 8 kilometers (25 by 5 mi). A report on the environmental status of the Mediterranean basin states that Israel has the largest number of plant species per square meter of all the countries in the basin.
Document 12: Range Creek: Range Creek, rising in the Book Cliffs in Emery County, Utah, is a high tributary of the Colorado River. It flows into the Green River, a major tributary of the Colorado. The creek flows year around.
Document 13: Mexico City: Mexico City is located in the Valley of Mexico, sometimes called the Basin of Mexico. This valley is located in the Trans-Mexican Volcanic Belt in the high plateaus of south-central Mexico. It has a minimum altitude of 2,200 meters (7,200 feet) above sea level and is surrounded by mountains and volcanoes that reach elevations of over 5,000 metres (16,000 feet). This valley has no natural drainage outlet for the waters that flow from the mountainsides, making the city vulnerable to flooding. Drainage was engineered through the use of canals and tunnels starting in the 17th century.
Document 14: Colorado River Compact: The Colorado River Compact is a 1922 agreement among seven U.S. states in the basin of the Colorado River in the American Southwest governing the allocation of the water rights to the river's water among the parties of the interstate compact. The agreement was signed at a meeting at Bishop's Lodge, near Santa Fe, New Mexico, by representatives of the seven states the Colorado river and its tributaries pass through on the way to Mexico.
Document 15: Death Valley: Death Valley is a desert valley located in Eastern California, in the northern Mojave Desert bordering the Great Basin Desert. It is one of the hottest places in the world along with deserts in the Middle East.
ground_truth: La Poudre Pass
sub_queries: where does the imperial valley get almost all of its water Answer: Colorado River
what is the source of Colorado River Answer: La Poudre Pass