Question: What is the source of the river where Southern California gets most of its water?

full_context: Document 1: 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 2: 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 3: 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 4: 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 5: 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 6: Geography of California: California is a U.S. state on the western coast of North America. Covering an area of , California is geographically diverse. The Sierra Nevada, the fertile farmlands of the Central Valley, and the arid Mojave Desert of the south are some of the major geographic features of this U.S. state. It is home to some of the world's most exceptional trees: the tallest (coast redwood), most massive (Giant Sequoia), and oldest (bristlecone pine). It is also home to both the highest (Mount Whitney) and lowest (Death Valley) points in the 48 contiguous states.
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: Roaring Rapids (Colorado River): Roaring Rapids are one of several rapids in the Black Canyon of the Colorado, 10.25 miles above El Dorado Canyon in the Colorado River between Arizona and Nevada.
Document 9: 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 10: Orange River: Orange Gariep, Oranje, Senqu River Sunset over the Orange River near Upington in the Northern Cape Countries Lesotho, South Africa, Namibia Tributaries - right Caledon River, Vaal River, Fish River (Namibia) Landmarks Gariep Dam, Augrabies Falls Source Thaba Putsoa - location Maloti Mountains (Drakensberg), Lesotho - elevation 3,350 m (10,991 ft) Mouth Alexander Bay - location Atlantic Ocean Length 2,200 km (1,367 mi) Basin 973,000 km (375,677 sq mi) Discharge - average 365 m / s (12,890 cu ft / s) The course and watershed of the Orange River, Caledon River and Vaal River. This map shows a conservative border for the watershed. Specifically, the Kalahari basin is excluded, as some sources say it is endorheic. Some other sources using computational methods show a basin which includes parts of Botswana (and hence of the Kalahari).
Document 11: 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 12: 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 13: Water in California: Rivers of the Lahontan watersheds in eastern California are part of the high desert Great Basin and do not drain to the Pacific. Most of the water is used locally in eastern California and western Nevada for irrigation. The Owens River of the South Lahontan region, however, is a principal source of water for Los Angeles.
Document 14: Riverside, California: Riverside is the 59th largest city in the United States, 12th largest city in California, and the largest city in California's Inland Empire metro area. According to the United States Census Bureau, the city has a total area of 81.4 square miles (210.8 km), of which 81.1 square miles (210 km) is land and 0.3 square miles (0.78 km) (0.37%) is water. The elevation of downtown Riverside is 860 feet (260 m). Hills within the city limits include Mount Rubidoux, a city landmark and tourist attraction. Riverside is surrounded by small and large mountains, some of which get a dusting of winter snow. Many residents also enjoy the many beaches of southern California. Riverside is about a 47 - mile drive to the Pacific Ocean and is close to Orange county and Los Angeles county.
Document 15: 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.
ground_truth: La Poudre Pass
sub_queries: where does southern california get most of its water Answer: The Colorado River
what is the source of The Colorado River Answer: La Poudre Pass