Water flows from the lake, through the tunnel, into a pipe called a penstock. The Annex Creek penstock is a riveted steel pipe 7,031 feet long. It varies in size from 42 inches in diameter and 1/4 inch thick at the valve house, to 34 inches in diameter and 5/8 of an inch thick at the powerhouse.

penstock-1

penstock-2


penstock - ankle