The lower and middle sections of the Klamath River are vulnerable to flooding , and major floods have occurred in years where major flooding has taken place in Northern California , particularly in the wake of Pineapple Express storms that bring large amounts of warm rain to Northern California . Fort Ter-Waw , located at what is now the town of Klamath Glen , was destroyed by the flood in December 1861 and abandoned on June 10 , 1862 . Other significant floods on the Klamath River have occurred in 1926 – 1927 , 1955 , 1964 , 1997 , and 2005 , in several cases changing the course of the river . The Christmas flood of 1964 was particularly devastating . The Klamath River reached flows of , submerging the town of Klamath under of water , with a high water reaching , inundating the towns of Klamath and Klamath Glen under as much as of water , and destroying most of the Highway 101 bridge crossing the river . The highway bridge was rebuilt in a different location , though entrances to the old bridge still stand
flood in December 1861
Great Flood of 1862
Klamath River