of Genesee Valley. From its source at the Indian and Spanish Creeks confluence, the East Branch North Fork flows west past Twain and joins the North Fork near Belden. The East Branch's main stem length is about . Indian Creek is about long, and Last Chance Creek is about long. The East Branch's most distant headwater is Last Chance Creek's source. The total length from the mouth of the East Branch to the source of Last Chance Creek is about . The total length of the Feather River from the source of Last Chance Creek to the Sacramento River is about . Middle Fork The Middle Fork Feather River begins at , in southeastern Plumas County about south of Beckwourth, at the north end of the Sierra Valley. It is formed by the joining of a number of tributaries that merge in an inverted river delta wetland with a complex network of irrigation ditches and drains called the Sierra Valley Channels. A number of creeks merge in the Sierra Valley, the longest of which is Little Last Chance Creek, which originates at and flows south through Frenchman Lake and Last Chance Valley to the Sierra Valley, where it divides into two distributary channels. Other tributaries that join to form the Middle Fork in the Sierra Valley include Carman Creek, Fletcher Creek, Turner Creek, Berry Creek, Hamlin Creek, Sierraville Creek, and Smithneck Creek. Flowing west through the mountains from its source in the Sierra Valley the Middle Fork is joined by Big Grizzly Creek, which drains Lake Davis to the north. Then the river flows through Portola and Delleker in the Humbug Valley. Sulphur Creek joins in the Mohawk Valley at Clio. Continuing west, the Middle Fork passes between Graeagle and Blairsden and further downstream south of Sloat in Long Valley. At Sloat, Long Valley Creek and Polar Creek enters the Feather. The Feather then enters a long and deep gorge. It is joined by numerous small tributaries. The Pacific Crest Trail crosses near Onion Valley Creek. The Middle Fork turns to flow southwest and south, through Bald Rock Canyon and the Feather River Canyon and on into the middle arm of Lake Oroville. The Middle Fork's main stem length is about , or about including Little Last Chance Creek. The total length of the Feather River from the source of Little Last Chance Creek to the Sacramento River is about