Montana Snowpack Report

Drew Christian Missouri River Fly Fishing Guide

We have finally reached the time of year when the majority of yak amongst fishing guides revolves around uncertain predictions on the future state of our water supply in Montana. As we ponder the ambiguous outlook of our season, it’s both exciting and worrying looking at what lies ahead. Will we have good hatches? Will the timing of run-off match the fishing we promised our anglers in June? Early season dry flies or hoot-owl restrictions in August? The answer to all these questions is actually quite simple: we don’t exactly know. We can only predict what might happen in the fishing season before us.

 As a young guide, I predominantly rely on objective data that’s collected through various sources as well as the shared expertise from old-timer guides. I imagine the 30 year veteran just walks out the front door, takes a look around, and instantly knows more about the water year than I do in 2 hours of internet research. In reality, there is a level of deserved confidence that comes with age and experience; but even the most veteran guide can only truthfully make a prediction. 

 So, what is the current jabber amongst fishing guides about our future season? The general consensus reigns good news for the year ahead. Additionally, an objective look at the current data available supports this speculation made by the tight knit guide community. 

Montana Snowpack

According to the NRCS: Snow Water Equivalent (SWE) is a common snowpack measurement. It is the amount of water contained within the snowpack. It can be thought of as the depth of water that would theoretically result if you melted the entire snowpack instantaneously.

According to the NRCS: Snow Water Equivalent (SWE) is a common snowpack measurement. It is the amount of water contained within the snowpack. It can be thought of as the depth of water that would theoretically result if you melted the entire snowpack instantaneously.

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From where we stand today, the current SWE looks around average in most of the state or above average in certain areas of SW Montana. This bodes well for the Bozeman area, westside, and Missouri River future water supply, but doesn’t guarantee we will have a continuous water supply trickling out of the mountains during the summer months. It really isn’t until Mid-April that we can determine how much water remains in the higher elevations for the late season water supply. That leaves us with an entire month of time for accumulation or dissipation of snowpack in the higher elevations. The only areas of concern in the entire state are the counties in the very NW corner and along the Idaho boarder. As evidenced by the map above, there is very slight drought conditions in Lincoln, Flathead, Ravalli, and Beaverhead counties.

Western US Snowpack

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For those of you that enjoy a larger picture of snowpack, the image to the left is the SWE by basin of the entire western United States. It mirrors a fairly typical snowpack that we would associate at this time of year with an El Nino winter weather pattern. That generally means hotter and drier than average conditions for us here in Montana compared to the lower Rockies and southern part of the west coast. According to the national climate center, El Nino conditions are expected to remain in North America for the rest of spring. Despite record setting temps. and a good amount of low elevation snow the past few weeks, we should expect to see above average temps re-appear and hang around for the greater part of spring. However, a more local forecast is actually predicting slightly lower than average temps. for the rest of March in Montana. You must take information from the weather man with a grain of salt.

Missouri River

Median Peak SWE for the Upper Missouri is April 18th, this is when we will actually know how much snow remains in the higher elevations for run-off/summer water supply.

Median Peak SWE for the Upper Missouri is April 18th, this is when we will actually know how much snow remains in the higher elevations for run-off/summer water supply.

A more complicated beast, the Missouri’s water supply is convoluted with a series of dams, irrigation districts, and a large watershed. Fun fact: The Missouri River is the longest river in North America draining over half-million square miles in 10 U.S. states and 2 Canadian provinces. If you combine its length with the Mississippi River, it becomes the 4th longest river system in the world.

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What does this mean for us in our small 30 something miles of blue ribbon trout water? The graph above tells us that we are sitting at an above average snowpack for early March. According to the information provided by the Bureau of Reclamation, “As of March 4, 2019 the snowpack is 119 percent of median. The March 1stSNOTEL data along with streamflow data was used to compute an April through July runoff inflow forecast volume into Canyon Ferry Reservoir of 2,322,200 acre-feet, or 130 percent of average. This is an average of Reclamation’s forecast (2,274.7 kaf), the U.S. Army Corps of Engineers forecast (2,673.0 kaf), and the NRCS forecast (2,018.8 kaf).”

If you are a visual person, like myself, the graph the right shows a summary of the projected water management coming out of Canyon Ferry, which ultimately results in our water flows for both below Hauser in the Land of Giants and in the Craig area below Holter Dam. It is important to remember that both Hauser and Holter Dams are managed as a “run of river” resource, meaning that basically what flows into them is what flows out of them as they are kept at near full 365 days a year. In essence, this leaves us with Canyon Ferry as the managing water body of the watershed. And it appears that they are planning on adjusting for the extra water this year by increasing flows from the reservoir earlier in the spring. This is a similar strategy we saw last year in 2018. However, we don’t have nearly as much snow as last year which theoretically will result in a more mellow run-off in May in June.

Take Away

  • We are sitting at or above average snowpack statewide in Montana, which bodes well for the fishing season ahead.

  • There is still a solid month left of time for the snow to change, but for now we are expecting a fairly average to slightly above average water year. Time will only narrow down the inaccuracy of this prediction.

  • We still also have to consider the rain amounts in the late spring/early summer to determine how the summer river flows will pan out. Remember last year when part of the state got hit with record breaking rainfall in June?

  • We are expecting a slightly colder March, but should eventually return to higher than average temperatures this spring.

  • The water managers of the Missouri River are gong to let some water out early to adjust for extra snow in the watershed, this should create more mellow streamflows in May and June. And it might make for higher water in April.

  • A full detailed report of the Montana water supply outlook can be found here.

  • We are going to be doing a “Flow-a-Thon” again this year with Missouri River peak flows. More details later on how you can win enough to pay for a day or two of guided fishing later in the season. All proceeds go to good groups who support the river.