Ah Pah Dam was a proposed dam on the Klamath River in the U.S. state of California proposed by the United States Bureau of Reclamation as part of its United Western Investigation study in 1951. It was to have been 813 feet (248 m) high and was to be located 12 miles (19 km) upstream of the river's mouth. It would stand almost as tall as the Transamerica Pyramid building in San Francisco, but would be much more massive. It would flood 40 miles (64 km) of the Trinity River, including the Yurok, Karuk and Hupa Indian Reservations, the lower Salmon River, and 70 miles (110 km) of the Klamath River, creating a reservoir with a volume of 15,000,000 acre feet (19 km3) - two-thirds of the size of Lake Mead, and becoming the largest reservoir in California. The water would flow by gravity through a