Summer Streamflow and Fishing Forecast — Mid April Update, by Walter

Batten down the hatches, everybody. The cold and wet pattern discussed in the previous updates has continued and we are now likely to have the highest and heaviest runoff since 2011, and therefore the second-heaviest since 1997. Late May and June fishing in the Yellowstone area is going to be limited to the Firehole, Madison, and Gibbon Rivers within Yellowstone Park, the lower Madison River, and private lakes. The Missouri River will be high but awesome (16-foot leaders and giant wire worms fished in the middle of the campgrounds). Once the Yellowstone drainage clears sometime in the middle of July, the fishing will be awesome, but failing an early warmup (not forecast), the river will clear late. There will be no stream closures in our primary area of operations this year. In fact, water flows are likely to remain above 2000cfs in the Yellowstone through the main season, and water temperatures should remain below 65 degrees–much less 70–throughout the summer. We expect gangbusters fishing this year, but it will take a while to arrive.

For what it’s worth, the next update will appear near the end of April. Don’t press me too hard if it comes out a little early or a few days late. I’m getting married April 28 and that (and the honeymoon) is going to cut into my time a bit, and quite rightly.


Here are some more details:

Winter began in September and October, with bitter cold and snow that never melted. I was in Alaska from about September 15 through 25, and it was colder in Montana (and the fishing is also less-crowded in Montana, really). November was warm, December and early January were near-average in precip and above normal in temps. Mid-January through the first half of March were cold and exceptionally wet, so that’s what made our winter. Late March alternated between warm and dry and cool and wet. April has been exceptionally cold and wet throughout the region. My ski hill, Bridger Bowl, closes today (Sunday the 15th), but it got 22 inches of snow Thursday-Friday and I had my deepest powder days (plural) of the season in April, with the deepest of all on Friday.

The cold and wet winter means that we now have drastically above normal snowpack in all basins within our operations area. Snowpack ranges from 128% of normal in the Madison-Gallatin drainage within Yellowstone Park to 175% of normal in the Yellowstone drainage in and above Yellowstone Park. Other drainages in our operations area run generally from 130% to 150% of normal. These numbers are well above last year’s at this time in all basins, generally between 20 and 40 points higher, though a few basins are more than 50 points higher. That said, the differences should not continue to increase, since late April and May 2017 were cold and snowy and we are now forecast to transition to near-normal conditions by the end of April.

The above means that it is now certain we will have dramatically above-average winter snowpack and thus almost certainly will have a prolonged and heavy runoff. In fact, all snow depth monitoring stations are now reporting snow water above the average yearly maximum, even though some high elevation snow stations typically continue to see snow depths increase for another three weeks or so. In other words, even if it doesn’t snow another flake, we will still wind up with above average snowfall. The only way this won’t translate into high streamflows this summer is if runoff begins catastrophically early with record warmth in late April. I do mean “catastrophically.” If it gets to 85 degrees for a few days around April 20-25, Livingston is going to wash away and wind up somewhere in North Dakota. This is not in the forecast. Our current 8 to 14-day outlook calls for more cold/wet weather, but the long term outlooks stretching into mid-May call for normal conditions.

So what is likely? A late start to the season on runoff-impacted waters, with “how late” depending on when runoff starts. If runoff starts earlier than normal but a typical rise in flows, things might only be several days late. If things start at the normal time, typically the end of the first week in May, odds are summer fishing in places like the Lamar will be delayed a ten days or perhaps two weeks (beginning around mid-July). If it keeps snowing through early May and May sees a slow warmup that doesn’t get the runoff started until May 20 or so, we could be looking at sometime in the latter half of July for the Yellowstone and Lamar systems, with good dry fly fishing not beginning until the last few days of July.


So what does all the above mean for specific fisheries? We can’t be sure until we see when runoff starts and how it progresses, but here are some prognostications. These will get more accurate and specific as spring progresses.

Yellowstone River: The Mother’s Day caddis may or may not happen in the first ten days of May. It depends on how the runoff progresses. Right now we do not honestly expect a good spring caddis hatch. We simply have too much low-elevation snow remaining. The most likely scenario is for it to warm up too fast and wash out the hatch. While we now expect some mud MOST days between about April 25 and May 5, runoff will probably hit in earnest sometime between May 5 and 15. We then expect the Yellowstone to be utterly blown out until at least July 1. After that, when it becomes fishable depends on how soon and how hard runoff hits. Right now we expect the Yellowstone to PROBABLY fall back into shape between July 7 and 15, hopefully around the 10th. If the river drops into shape before the 15th, we should have at least some Salmonfly hatch fishing outside the park. If it’s after the 15th, the hatch will probably be blown out for float trips. That said, the hatch will almost certainly continue through July 25 in the canyons in the park, and maybe into early August. Thus, there will be hike-in “big bug” fishing even if we don’t have any outside the park. Once the river drops into shape, we expect VERY GOOD TO EPIC fishing all summer and through the fall. There’s just going to be too much cold water running downhill for a realistic chance of too-warm water this year. The dry fly fishing in late July and August in particular should be very good, provided you’re up for chucking your flies into the bushes… Yankee Jim Canyon should become fishable sometime in the middle two weeks of August, if you like floating this water with Walter. Absent a record-dry summer, it should remain floatable through September. This means this will be another rare year which should see the opportunity to fish the fall BWO and Drake Mackeral hatches in the canyon (40-fish, one-angler half-day guide trips, all on dries, the last year this happened, FYI). High streamflows actually help the fall fishing as well as the late summer fishing, particularly early in the morning, since when the river is carrying more water in the fall its temperatures do not yo-yo as much overnight. This leaves a broader window of 50-55 degree water during the course of the day, which is prime for our beloved fall BWO hatches.

Special Note on Yellowstone River Float Trips: Because of our uncertainty in when the Yellowstone will drop into shape, we are not currently accepting “Yellowstone float trip only” bookings prior to July 20. If you want to plan for a Yellowstone float before that, great, but if the river turns out to be muddy we will need to plan to do something else, either a Madison float, a Missouri jet boat trip, a park walk/wade trip, or a private lake float. We will be posting special discounted summer rates for Missouri River jet boat trips soon, to take into account the high water on the Yellowstone and the fact the “MO” should fish great well into July this year.

Lamar, Soda Butte, and Slough: Will probably fall into shape between July 10 and 15, though this could be delayed until the 20th or after if runoff is dramatically delayed. Green Drake hatches should be strong through the middle of August, and this could be a year when there isn’t much of a late August/early September doldrums on these waters as there usually is. The real key for these waters is when runoff starts and how severe it is during the month of May. They always offer good fishing in the summer, since they’re up high and cold, it’s just a question of when it will start.

Firehole, Gibbon, and Madison in YNP these will be the big beneficiaries in the early season. The Firehole will be the star of the show through at least June 15. The Madison is unlikely to be very good before June 10. I expect both the Madison and the Gibbon to fall gradually into play between the 10th and 15th of June. The Firehole will stay cool and good (they are one and the same on that river) through at least July 1, and probably July 5-10 at least in the mornings, maybe even July 15 if July starts off cool. The Gibbon will be good until July 15 at least, and maybe through July. The meadows should see good Green/Gray/Brown Drake fishing in July. The Madison will be about the same, and this is one of those years where if we have a cool summer it might only see a couple weeks of doldrum in early August, wherein even the mornings might still fish.

Lower Madison River: The stretch of the Madison downstream of Ennis Lake should remain fishable through the spring runoff, except perhaps when its major tributary Cherry Creek is at peak runoff. While not a GREAT float stretch (the best section of the Madison is upstream of Ennis Lake and outside of our ops area), this will be the only float river within easy day-trip range of Gardiner that will remain fishable in June. It’s often too warm by June 20-25, but this year it should be fine through July 15 or so absent an extreme warmup in early July. If you do want to float-fish in June or early July, and you can’t swing a trip to the Missouri or don’t want to deal with the “mrrrrrrrrrrr” of an outboard, this is where we’ll plan to go. Note that we’re still looking at a 2hr drive or so from Gardiner to get here.

Missouri River: The Missouri is already very high, near record levels for the date in fact, since they are already drawing down the reservoirs to keep flows reasonable in late May and early June. That said, late May and early June should be BIG. Expect flows in the 12,000 to 16,000cfs range. The river needs a good flush so we are glad of it. In regards to what this means for the fishing: book your trips now for late May and June. Do it now. I mean right now. Last year when flows were over 10,000 in the latter half of May and first week of June, Walter had his best guided trips ever on the Missouri. Fat silver rockets that were gorging on dislodged eggs and especially sowbugs. Fish under 16 inches were getting into the backing even though the clients were running 3X leaders. You just have to like nymphing, and often deep nymphing. The leaders we were running were 3 feet of 20lb bright orange Amnesia, seven feet of 2X, and a foot of 3X fluoro to the top fly (a sowbug, always), with up to four split shot. Later in June, the flows should remain high enough to push caddis-eaters and early PMD-eaters to the banks. Walter had his only good “Land of Giants” dry fly fishing with clients ever during the last high water year (in 2014). This was sight-fishing to pods of dry fly eaters averaging 18 inches and reaching 24 inches. We can’t guarantee the same this year, but we hope and expect it…

Keep an eye on our Main Web Site (which was updated a couple weeks ago, BTW) for details on extended sale pricing on jet boat trips this season.

Small Streams: Except for a couple meadow streams, especially those that run out of lakes in Yellowstone Park, these aren’t even going to be worth thinking about until the middle of July or after. The meadow creeks MIGHT be worth fishing by June 15, and certainly by June 25. Except for the lake-fed creeks, which will be best in July, August and early September is certainly going to be the best time on all the small creeks in Yellowstone, with late August probably the best time except on the brookie streams, where late July and early August will be better.

Small Lakes in YNP: Those that are legal to fish on the opener will still generally be snowbound and/or frozen. They will be reachable and open by June 15 and fish best for the month thereafter. Be prepared to hike in waders, because the trails will be marshy and will still have snow patches through June.

Spring Creeks and Private Lakes: Not impacted by runoff and as such very good choices this year (as well as any year) from basically right now through early July in the case of the lakes, and through July in the case of the creeks. Your prime PMD days in early July are already fully booked on the spring creeks, alas.

More details and specifics in later updates.

4 comments on “Summer Streamflow and Fishing Forecast — Mid April Update, by Walter

  1. What is the fishing forecast for the upper Madison? Do you think it will be wadable in late June? I understand it is out of your ops area but your input would be appreciated.

    • It depends on how late in late June and how aggressive you are. I would think “between the lakes” will be fine after the 20th for sure. The further down you get, the rougher/faster/browner/more up in the bushes it will be. The Madison typically clears two weeks before the Yellowstone. We figure the Yellowstone will be ready July 5-15, probably by the 10th (we had warm weather since the last update and the spring runoff has basically begun). So the Madison should be ready by June 25. That said, it will still be really high and you’ll be fishing right along the banks and crashing through bushes to do it.

  2. Hello. For the first week in June, other than the Firehole, are there other options near West Yellowstone? Any lakes? Thanks for your help.

    • I think Richard already replied, but I doubt it. There weren’t last year and we have far more snow this year.

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