The upper Madison River flows are controlled at Hebgen Dam. Madison River flows are highest during the spring runoff as the snow melt is at it's peak. The duration and magnitude of the runoff is determined by the amount of snow we receive each winter.  The biggest misconception about spring runoff is that the fishing terrible. This couldn't be further from the truth. We see some extremely productive days during the highest and dirtiest flows. The lowest flows on the Madison River come near the end of summer and middle of winter. Flows under 900 CFS make for some skinny water, but nonetheless, the Madison River stays floatable year-round. 

Upper Madison River Flows near Cameron, MT

Water Level Graph for USGS Station 06038800 Source

Upper Madison River Water Temperature near Cameron, MT

Water Temperature Graph for USGS Station 06038800 Source

Lower Madison River Flows below Ennis Lake

Water Level Graph for USGS Station 06041000 Source

Lower Madison River Water Temperature below Ennis Lake

Water Level Graph for USGS Station 06041000 Source