In the Talkeetna Mountains, flows SE dividing Fortress Ridge, to Caribou Creek, 87 mi NE of Anchorage. 6.1 miles long.
Named by U.S. Geological Survey (USGS) in 1956; derived from Fortress Ridge through which the stream flows.
Bug Lake, Hicks Lake, Hundred Mile Lake,
Mountains:Gunsight Mountain, Horn Mountain, Lion Head, Sheep Mountain, Syncline Mountain, Mount Wickersham,
Ridges:Rivers:East Fork Matanuska River, South Fork Matanuska River,
Streams:Alfred Creek, Ammonite Creek, Bench Creek, Billy Creek, Bitter Creek, Caribou Creek, Chitna Creek, Dan Creek, Divide Creek, Flume Creek, Fortress Creek, Glacial Fan Creek, Glacier Creek, Greta Creek, Gypsum Creek, Inoceramus Creek, McDougall Creek, Mouse Creek, Papoose Creek, Rock Glacier Creek, Sawmill Creek, Sawmill Creek, Sheep Creek, Sladen Creek, Squaw Creek, West End Creek, Whistler Creek, Wood Creek, Yellow Jacket Creek,
Valleys: