Question: What California highway is the longest in the state and is associated with the Ventura River?

full_context: Document 1: U.S. Route 66 in California: U.S. Route 66 (US 66, Route 66) is a part of a former United States Numbered Highway in the state of California that ran from the west in Santa Monica on the Pacific Ocean through Los Angeles and San Bernardino to Needles at the Arizona state line. It was truncated during the 1964 renumbering and its signage removed in 1974. The highway is now mostly replaced with several streets in Los Angeles, State Route 66 (SR 66), Interstate 15 (I-15) and I-40.
Document 2: U.S. Route 66: U.S. Route 66 (US 66 or Route 66), also known as the Will Rogers Highway, the Main Street of America or the Mother Road, was one of the original highways within the U.S. Highway System. US 66 was established on November 11, 1926, with road signs erected the following year. The highway, which became one of the most famous roads in the United States, originally ran from Chicago, Illinois, through Missouri, Kansas, Oklahoma, Texas, New Mexico, and Arizona before ending at Santa Monica, California, covering a total of 2448 mi . It was recognized in popular culture by both the hit song "(Get Your Kicks on) Route 66" and the "Route 66" television show in the 1960s.
Document 3: Carneros Creek (Santa Barbara County, California): Carneros Creek is a southward flowing stream originating in the Santa Ynez Mountains, in Santa Barbara County, California. It flows to Lake Los Carneros Park, under U. S. Highway 101 where it runs in a man-made channel diverted to the west of Santa Barbara Municipal Airport, until it meets Goleta Slough, from whence its waters flow to the Santa Barbara Channel of the Pacific Ocean.
Document 4: Route of California High-Speed Rail: The California High-Speed Rail system will be built in two phases. Phase 1 will be about 520 miles long, and is planned to be completed in 2029, connecting the downtowns of San Francisco, Los Angeles, and Anaheim using high-speed rail through the Central Valley. In Phase 2, the route will be extended in the Central Valley north to Sacramento, and from Los Angeles east through the Inland Empire and then south to San Diego. The total system length will be about 800 miles long. Phase 2 has no dates as yet.
Document 5: East Branch South Fork Eel River: The East Branch South Fork Eel River, a tributary of the South Fork Eel River, is formed by the confluence of Cruso Cabin Creek and Elkhorn Creek, in Mendocino County in the U.S. state of California. The river is roughly 25 mi long, meandering west to its confluence with the South Fork Eel at Benbow Lake State Recreation Area. Major tributaries of the East Branch include Buck Mountain Creek, Squaw Creek, Rays Creek, and Tom Long Creek. The river flows west, turns north, and flows west again, through rugged terrain in the Coast Range of California. The East Branch is the South Fork Eel's largest tributary.
Document 6: Cedar Creek (South Fork Eel River): Cedar Creek is an 11.2 mi tributary of the South Fork Eel River in Mendocino County in the U.S. state of California. The creek begins southeast of Red Mountain, at an elevation of 778 ft . It makes an S-curve west-northwest then bends sharply south, dropping into the valley of the South Fork Eel. The confluence is south of the city of Leggett, on the river's right bank. The only named tributary of Cedar Creek is Little Cedar Creek, a headwaters tributary. Big Dann Creek joins the South Fork Eel on the same bank, just upstream of Cedar Creek, while the next major tributary downstream of Cedar is Rock Creek. The Cedar Creek watershed is rugged and has few tributaries.
Document 7: Lincoln Highway: The Lincoln Highway was one of the earliest transcontinental highways for automobiles across the United States of America. Conceived in 1912 by Indiana entrepreneur Carl G. Fisher, and formally dedicated October 31, 1913, the Lincoln Highway ran coast-to-coast from Times Square in New York City west to Lincoln Park in San Francisco, originally through 13 states: New York, New Jersey, Pennsylvania, Ohio, Indiana, Illinois, Iowa, Nebraska, Colorado, Wyoming, Utah, Nevada, and California. In 1915, the "Colorado Loop" was removed, and in 1928, a realignment relocated the Lincoln Highway through the northern tip of West Virginia. Thus, there are a total of 14 states, 128 counties, and more than 700 cities, towns and villages through which the highway passed at some time in its history.
Document 8: Interstate 80: Interstate 80 (I-80) is a transcontinental limited-access highway in the United States that runs from downtown San Francisco, California, to Teaneck, New Jersey, in the New York City Metropolitan Area. The highway was designated in 1956 as one of the original routes of the Interstate Highway System. Its final segment was opened to traffic in 1986. It is the second-longest Interstate Highway in the United States, following I-90. The Interstate runs through many major cities including Oakland, Sacramento, Reno, Salt Lake City, Omaha, Des Moines, and Toledo, and passes within 10 mi of Chicago, Cleveland, and New York City.
Document 9: Casitas Dam: Casitas Dam is an earthfill dam across Coyote Creek that forms Lake Casitas in Ventura County, California near Oak View, California. The dam is located two miles (3 km) above the junction of Coyote Creek and the Ventura River. Water from the Ventura River is diverted to Lake Casitas as well. The 334 ft structure was built by the U.S. Bureau of Reclamation. It is a key part of the Ventura River Project. Construction was completed in 1959. Lake Casitas has a 254000 acre.ft storage capacity and provides irrigation and municipal uses for the Casitas Municipal Water District.
Document 10: Cottonwood Creek (Sacramento River): Cottonwood Creek is a major stream in Northern California in the United States and is a tributary of the Sacramento River. About 68 mi long measured to its uppermost tributaries, the creek drains a large rural area bounded by the crest of the Coast Ranges, traversing the northwestern Sacramento Valley before emptying into the Sacramento River near the town of Cottonwood. For its entire length, it defines the boundary of Shasta County and Tehama County. Because Cottonwood Creek is the largest undammed tributary of the Sacramento River, it is known for its Chinook salmon and steelhead runs.
Document 11: U.S. Route 101 in California: U.S. Route 101 (US 101) in the state of California is one of the last remaining and longest U.S. Routes still active in the state, and the longest highway of any kind in California. US 101 was also one of the original national routes established in 1926. Significant portions of US 101 between the Los Angeles area and the San Francisco Bay Area follow El Camino Real, the historic road connecting the former Alta California's 21 missions.
Document 12: Lake Casitas: Lake Casitas is a man-made lake in Ventura County, California, created by the construction of Casitas Dam on Coyote Creek, two miles (3 km) before it joins the Ventura River. Santa Ana Creek and North Fork Coyote Creek also flow into the lake. The dam was constructed of earth-fill and was completed in 1959. It is 279 ft and was built by the United States Bureau of Reclamation. The lake has a capacity of 254000 acre.ft . The dam was built as part of the Ventura River Project and was strengthened in June–December 2000 as a seismic improvement to help withstand earthquakes greater than 6.5. The project provides drinking water and water for irrigation. A secondary benefit is flood control. In the center of Lake Casitas is 2 km Main Island, whose peak rises more than 500 ft from the lake surface.
Document 13: Ventura River: The Ventura River, located in western Ventura County in southern California, United States, flows through an eponymous narrow valley with steeply sloped sides. The smallest of the three major rivers in Ventura County, the Ventura River main stem begins at the confluence of Matilija Creek and North Fork Matilija Creek, 16.2 mi from the Pacific Ocean. Matilija Creek is Ventura River's most significant headwater and tributary, and adds 17.3 miles to the length of the river's main drainage. San Antonio Creek, the river's second most significant tributary, joins the river from the east halfway to the ocean; Coyote Creek enters the river from the west and Cañada Larga Creek from the east a few of miles downstream. In its final stretch, the Ventura River flows through the Ventura River estuary, which extends from about the 101 Freeway bridge to the Pacific Ocean.
Document 14: El Camino Real (California): El Camino Real (Spanish for The Royal Road, also known as The King's Highway), sometimes associated with Calle Real (within the US state of California), usually refers to the 600-mile (965-kilometer) road connecting the 21 Spanish missions in California (formerly Alta California), along with a number of sub-missions, four presidios, and three pueblos, stretching at its southern end from the San Diego area Mission San Diego de Alcalá, all of the way up to the trail's northern terminus at Mission San Francisco Solano in Sonoma, just above San Francisco Bay.
Document 15: U.S. Route 61: U.S. Route 61 (US 61) is the official designation for a United States highway that runs 1400 mi between New Orleans, Louisiana, and the city of Wyoming, Minnesota. The highway generally follows the course of the Mississippi River, and is designated the Great River Road for much of its route. As of 2004, the highway's northern terminus in Wyoming, Minnesota, is at an intersection with Interstate 35 (I-35). Until 1991, the highway extended north on what is now Minnesota State Highway 61 (MN 61) through Duluth to the Canada–US border near Grand Portage. Its southern terminus in New Orleans, Louisiana, is at an intersection with Tulane Avenue at South Broad Street. The highway is often called the Blues Highway because it connects Saint Paul, Minnesota; St. Louis, Missouri; Memphis, Tennessee; the Mississippi Delta, and New Orleans.
ground_truth: U.S. Route 101