As of now fly fishing on the Madison river is pretty good. The upper sections of the river are now open and most anglers are cleaning up on all those dumb trout that are accessible now that the winter closure has lifted. They are even lucky enough to be fishing in abnormally clear water conditions. The water has plenty of clarity to catch fish but enough color to keep them from being too picky about the fly, leader or drift.
However, it also looks like we are in the midst of this years runoff on the Madison river and many of the other rivers in our area. The Yellowstone and Gallatin rivers are plenty dirty and the flow on the upper Madison river has spiked despite no increased release from the dam. We have a lot of rain in the past week, which is contibuting to increased flows but the better part of our snow is gone at this point. The map below shows the percentage of yearly snowpack for various drainages in western Montana. There is not a lot of snow up there. The Madison river drainage as a whole is down to 43% of average snowpack. Most of the Snow is gone and the river is still plenty fishable. It looks like we may have little to worry about interns of runoff and really dirty water for this year.
With a snowpack well below the normal average for this time of year what can we expect water conditions to be like in mid to late summer? The mid to late summer water levels on the Madison river depend a lot more on what comes out of Hebgan dam than on the current level of snowpack. On a normal year the majority of a winter's snow flushes through the river during the yearly spring runoff. After runoff a much higher portion of the water in the Madison river comes from Hebgan lake. The the link below will take you to a frequently updated site where you can track the levels of Hebgan lake:
http://www.usbr.gov/gp-bin/arcweb_hebr.pl
As now Hebgan lake levels look good:
Daily Reservoir Data as of 05/18/2015
Pool Elevation is 6533.1 Feet
Pool Elevation to Fill 1.8 Feet
Reservoir Storage is 362883. Acre-Feet
Reservoir Storage to Fill 23297.7 Acre-Feet
Reservoir Inflow is 638.5 CFS
Reservoir Outflow is 575.0 CFS
Reservoir is 94.0 % Full*
Reservoir Flood Control Pool is filled 0.0 %
Madison River Flow is 575.0 CFS
The lake is 94% full and there is currently more water coming in than going out. For now it looks like we are going to end up with a mild runoff and plenty of water in the lake to sustain us through the summer.