The Missouri River that fly fisherman are concerned with is about 35 miles of river. From Holter Lake dam to the town of Cascade, MT. The river is like a big spring creek. The MO gets all of the hatches that a spring creek would just with more fish, hot fish, beautiful fish. Did I mention the views, out of this world. The Missouri flows along the Rocky Mountain front range.
Read a newspaper article about the Missouri River that I was interviewed for at Helena IR.