The origin of great rivers starts at their headwaters. Usually high in a mountain range, resource-rich waters gather as the basis for raging rivers and deep lakes. Every stream works its way around obstacles. Streams merge, become rivers, gain momentum and power to shape their own direction. The source of a rivers origin, their headwaters, remain the single most vital defining point without which the trip would not be possible. Fly fishermen know the headwaters are often where the largest trout hang because everything they need resides there.