Missouri River 2018 Snow and Flow

Holter Dam

Yesterday, Garrett and I attended the annual meeting of the Upper Missouri Water Advisory Group. It’s essentially a gathering of all the bean counters that work in the watershed of the upper Mo, everyone from fishery biologists to the Bureau of Reclamation and Northwestern Energy attends. As guides and outfitters there is a lot of information in an afternoon long meeting that is irrelevant to our fishing season. However, the two most important topics we want to share with our anglers are predicted streamflows for the Mo and the latest fish counts. Here is the short version.

Missouri River Flow


Our snowpack this year is huge statewide. Most watersheds are sitting in the 130%-160% of a normal average. The main stem Missouri is at 157%. And since April 15th is the magic day where snowpack is set for the season, it’s a safe bet we have the snow necessary for a good water year. So what does this mean? Well, it means we have the snowpack and the potential for a huge water year below Holter. It doesn’t guarantee it though, we could hit drought weather next week. The dam folks have a predicted range of everything from the huge 2011 type flows to normal 4,000cfs low water year flows. See the water year graph below.

Missouri River Fly Fishing

What we do know is that for now they are emptying a little extra water out of our lake system early; so we can expect above average flows for the rest of the pre-runoff time of April and early May. Anyone who has been out to the river lately has seen this and it looks good out there. 6Kcfs is a nice healthy flow on the river. Only time will tell how it all will pan out, but we like where we are sitting. It’s much better to have a high water year than low summer flows. It’s good for fishing, great for the fish, and helps decrease our seasonal water temps.

Missouri River Fish

Every year the Montana FWP Biologist for the Mo presents their annual fish survey data to the public. They take samples from two areas on the river, Craig and Cascade. The data is as follows:

Craig Section(Wolf Creek Bridge to Craig FAS)

  • 4,936 Rainbow trout per mile with a large age class in the 16-18 inch range.
  • 576 Brown trout per mile with an average size in the 12-15 inch range.

Cascade Section(2 miles above and below Pelican Point FAS)

  • 1,592 Rainbow trout per mile.
  • 387 Brown trout per mile with a large age class in the 15-18 inch range.
  • 20 Brown trout per mile in the 20-24 inch age class.

Essentially, our fish population on the Missouri below Holter Dam continue to hold steady at nothing short of amazing. All the fish counts are either at or way above the long term average and there are a large amount of big fish. There is also data supporting a smaller age class of fish which bodes well for the future of the fishery. For more information on our fish populations, the Helena IR did a recent article re-capping all data presented by Montana FWP.

Take Home Points

There is a load of information available when it comes to these types of studies and predictions. It is always important to remember that we are dealing with Mother Nature and wild trout, most of what actually happens is out of our control. That is part of the fun of fly fishing.

  • The stage is set for a huge water year on the Mo, we are currently sitting very similar to previous big water years. However, weather can change. I think the most important take home is many of the experts at the meeting seemed to be thinking good thoughts about having this much water. 
  • Our fish populations are A+ on the Missouri right now. Large fish and many of them, the biologists seem pleased and very happy about the results they are getting. 
  • Even though fish populations look good and water flows are aligned to be healthy we mustn't let our guard down. We still have to take care of our recourse and protect it against negative impacts such as aquatic invasive species.