Flowing west, it is joined by Big Grizzly Creek, with waters from Lake Davis.

The river continues west, passing Portola and turning northwest at Clio,[6] where it is joined by Sulphur Creek.

[7][8][9] The Middle Fork is recognized by the US Government for its untamed beauty and is designated a National Wild and Scenic River for 77.6 miles of its length.

[10] The 32.9 mile stretch inaccessible to roads is home to some of the best wild trout fishing in California.

The Grizzly Valley is a 21 sq mi (54 km2) landform of the upper Middle Fork Feather watershed that receives 29-37 inches of annual precipitation.