Question: What river provided the name for the county, which borders another county, where Hidden Valley can be found?

full_context: Document 1: Jersey Bridge (Cherrytree Township, Pennsylvania): The Jersey Bridge is a one-lane, Pratt through truss bridge that spans Oil Creek in Cherrytree Township, Venango County in the U.S. state of Pennsylvania. It connects the city of Titusville to the Drake Well Museum and Oil Creek State Park. The bridge was listed on the National Register of Historic Places in 1988. It was replaced in 1998 with a newer bridge that used the superstructure of the old bridge.
Document 2: Hidden Valley, Placer County, California: Hidden Valley (formerly, Union House) is an unincorporated community in Placer County, California. Hidden Valley is located east-southeast of Rocklin. It lies at an elevation of 436 feet (133 m).
Document 3: Homestead Grays Bridge: The Homestead Grays Bridge, also known as the (Homestead) High Level Bridge, was built in 1936 and spans the Monongahela River between Homestead Borough and the southernmost tip of Pittsburgh's Squirrel Hill neighborhood. It is notable as the first bridge to incorporate the Wichert Truss, which uses a quadrilateral shape over each support, into its design. This made the truss statically determinate, so that forces in the structural members could be calculated.
Document 4: Hidden Valley, Indiana: Hidden Valley is a private residential community in Dearborn County, Indiana, United States. For statistical purposes it is a census-designated place (CDP), with a population of 5,387 at the 2010 census, up from 4,417 at the 2000 census.
Document 5: Hidden Valley Farm: Hidden Valley Farm is a historic home and farm complex located at Baldwin, Harford County, Maryland, United States. It consists of a mid-19th century vernacular Greek Revival brick farmhouse with several auxiliary structures. The house is a three-story, rectangular brick dwelling with a gable roof, with a two-story wing. The house features square-columned one-story porches across the façade and both sides of the wing. Also on the property are a mid-19th century barn, summer kitchen, and smokehouse, and later wood shed and garage.
Document 6: Herr's Island Railroad Bridge: The Herr's Island Railroad Bridge, also known as the West Penn Railroad Bridge, is a truss bridge across the Allegheny River between the Pittsburgh neighborhoods of Troy Hill and Herrs Island (commonly referred to as Washington's Landing).
Document 7: Upper Twin Island: Upper Twin Island is a bar island in Ohio County, West Virginia on the Ohio River. It lies upstream from its twin, Lower Twin Island. Both islands are part of the city of Wheeling and situated between Martins Ferry, Ohio and mainland Wheeling.
Document 8: Green Bay Road Bridge: The Green Bay Road Bridge is a Pratt pony truss bridge across the Manitowoc River in Manitowoc Rapids. The bridge was built in 1887 by the Wisconsin Bridge and Iron Company and was the second river crossing built at its location. Originally a road bridge, the bridge is now used for a bicycle and walking trail; it is in good condition and is considered a historically significant example of a pony truss road bridge. The bridge was added to the National Register of Historic Places on August 3, 1998.
Document 9: Center Township, Dearborn County, Indiana: Center Township is one of fourteen townships in Dearborn County, Indiana. As of the 2010 census, its population was 5,318 and it contained 2,267 housing units.
Document 10: Richmond, Virginia: There are also parks on two major islands in the river: Belle Isle and Brown's Island. Belle Isle, at various former times a Powhatan fishing village, colonial-era horse race track, and Civil War prison camp, is the larger of the two, and contains many bike trails as well as a small cliff that is used for rock climbing instruction. One can walk the island and still see many of the remains of the Civil War prison camp, such as an arms storage room and a gun emplacement that was used to quell prisoner riots. Brown's Island is a smaller island and a popular venue of a large number of free outdoor concerts and festivals in the spring and summer, such as the weekly Friday Cheers concert series or the James River Beer and Seafood Festival.
Document 11: Laughery Creek Bridge: The Laughery Creek Bridge is a truss bridge on the border of Dearborn County, Indiana, and Ohio County, Indiana. It crosses Laughery Creek. This bridge was built in 1878. The Wrought Iron Bridge Company, a prolific late 19th-century bridge company, constructed the bridge. The bridge is seated on stone abutments. The deck surface is not original and is currently concrete. The bridge, nearly 300 feet in length, is a single span pin connected triple intersection Whipple through truss, and is the only example in the world of this truss type. The name bridge's nickname, "Triple Whipple Bridge" is a play on words. The double-intersection Pratt, which was called the Whipple truss configuration, was a far more common variation of the standard Pratt configuration. Since the Laughery Creek Bridge's members have three intersections instead of two, this gives rise to the "Triple Whipple" name. This bridge was listed on the National Register of Historic Places in 1976.
Document 12: Kentucky & Indiana Terminal Bridge: The Kentucky & Indiana Bridge is one of the first multi modal bridges to cross the Ohio River. It is for both railway and common roadway purposes together. By federal, state, and local law railway and streetcar, wagon-way, and pedestrian modes of travel were intended by the City of New Albany, City of Louisville, State of Kentucky, State of Indiana, the United States Congress, and the bridge owners. The K & I Bridge connects Louisville, Kentucky to New Albany, Indiana. Constructed from 1881 to 1885 by the Kentucky and Indiana Bridge Company, the original K&I Bridge opened in 1886. It included a single standard gauge track and two wagon ways, allowing wagons and other animal powered vehicles to cross the Ohio River by a method other than ferry for the first time. At the time motorized vehicles were virtually nonexistent. The K&I Bridge company also owned a ferry boat operation during both the 1st and 2nd bridge; eventually that operation was sold as the bridge's success largely outmoded boat usage.
Document 13: Captina Island: Captina Island is an island on the Ohio River in Marshall County, West Virginia, USA. Powhatan Point, Ohio is located on the opposite shore from Captina Island. It lies at the southern end of Round Bottom with a stream-like channel separating the island from the West Virginia shore. Captina Island was once the place where watermelons were grown for the Marshall County Fair. It is part of the Ohio River Islands National Wildlife Refuge.
Document 14: Harrison Township, Dearborn County, Indiana: Harrison Township is one of fourteen townships in Dearborn County, Indiana. As of the 2010 census, its population was 3,204 and it contained 1,338 housing units.
Document 15: Brooks Island (West Virginia): Brooks Island is an island in Raleigh County, West Virginia on the New River. It is located approximately two miles south of Brooks Falls near the unincorporated community of Brooks.
ground_truth: Ohio River
sub_queries: Hidden Valley >> located in the administrative territorial entity Answer: Dearborn County
Dearborn County >> shares border with Answer: Ohio County
Ohio County >> named after Answer: Ohio River