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Category: Snowpack, Streamflow, and Summer Fishing Predictions

Updates on winter snowpack and likely summer streamflow and fishing conditions, mostly posted from January through June

Runoff Report and Summer Streamflow and Fishing Outlook

Runoff Report and Summer Streamflow and Fishing Outlook

Walter just posted an in-depth snowpack and runoff report and an outlook for summer streamflows and fishing over at Yellowstone Country Fly Fishing. Rather than reinvent the wheel, we suggest you click this link for the details.

Long story short, we have low snowpack and runoff is near its peak. We anticipate a low runoff, an early end to runoff, and low, warm streamflows this summer. In general the best opportunities will be in the first three weeks of July before things drop too much, though after that the fishing will still be good as long as it’s not super hot and dry. If it IS super hot and dry… well, we might be doing a lot of 6AM to 2PM trips and morning half-days.

Early May Snowpack Update & Streamflow Forecast

Early May Snowpack Update & Streamflow Forecast

Walter made a snowpack and streamflow update on his business website. Rather than reinventing the wheel, go check it out.

In sum, we had an early start to the spring melt due to downright not weather the last few days of April, but early May is forecast to be cool and wet. This should stall the HEAVY runoff until at least May 15-20 and will certainly lead to good fishing on the Yellowstone, Boulder, and Stillwater once the first flush of runoff drops out in a couple days.

Overall, snowpack is low. We expect low streamflows and an early start to most summer fishing as the water drop sooner than usual. This is good for late June and early July fishing. It’s not so good for late July and August fishing, when we anticipate low flows and warm water that might prompt “early-on, early-off” trips for optimum results as well as some mandatory closures in warm, low-elevation waters. These waters are mostly in Montana, though it’ll be a short season on the Firehole this June.

Snowpack Update and Summer Streamflow and Fishing Forecast

Snowpack Update and Summer Streamflow and Fishing Forecast

Walter has posted a summer streamflow forecast over at his own website. Rather than reinventing the wheel, here’s a link.

Note that Walter’s own operations area extends a bit further east (to the Stillwater River) and west (to the Jefferson River) than the shop’s does, since he’s an hour closer to these waters.

The next update will be posted in mid-April.

2021 Snowpack Update and Season Streamflow Forecast

2021 Snowpack Update and Season Streamflow Forecast

Walter just posted a thorough season streamflow update over on his personal website. Rather than reposting it here, we’ll just suggest you head over there.

Long story short is that we are at 90-108% of average snowpack in the drainage basins that impact our operations. While not bad, this isn’t as high as we would like to be sure of good August water conditions.

The long-term outlooks do not suggest significant improvement in the above numbers for the remainder of the winter. We’re instead likely to remain flat or have the numbers decline a bit over the next six to eight weeks before the heavy spring melt begins.

So we’ll likely be near average in the Yellowstone Basins (at 106-108% now), but below average in the Madison Basin, which includes the Firehole and Gibbon (at 90-91% now).

The next update will pop around April 1, and no it won’t be a joke.

Continued Improvement in 2021 Snowpack and Fishing Season Outlook

Continued Improvement in 2021 Snowpack and Fishing Season Outlook

Ten days back I posted about how I was holding off on posting about our current snowpack and what it means for the 2021 fishing season. I’m STILL not going to go into extreme detail because we’re STILL getting tons of snow.

The above is great news for the 2021 fishing season. Back at the beginning of January we were hurting, and January itself was dry, too. I was still on my “rock” snowboard on February 1 because not only were a few rocks still exposed at Bridger Bowl, there were also stumps, bushes, and clumps of grass, when all that junk is usually buried.

Simply put, we were looking at a drought season three weeks ago, with the possibility of widespread late afternoon fishing closures if summer turned out hot. Now we’re fast approaching exactly where we want to be for snowpack, which in turn bodes well for summer streamflow and fishing conditions.

A quick reminder before I lay out some numbers: most of our summer water comes from winter snow. Once runoff peaks in June, the water continually drops until sometime in September when fall rains usually raise things a swidge again for a few weeks before rivers drop to their winter low flows. High snowpack means a high peak runoff means higher flows and colder water temperature through summer means happier and healthier trout means much happier fishing guides and clients.

All in all, we like snowpack to be 100 to 115% of normal at the end of April. This sets us up for normal to slightly high streamflows no matter what happens for summer temperatures and rainfall.

It does mean our summer fisheries (Yellowstone, Boulder, and Stillwater Rivers for floating, northern YNP for wade-fishing) start in early July instead of late June, but it sets these fisheries up for much better conditions from about July 20 through mid-September. Anyway, we have plenty of other spring fishing options now that Walter is running power boat trips and we float the Lower Madison. These fishing options are great during the May to early July runoff season.

Here’s where the important drainage basins in our operations area stand as of Feb 17. They’re given in order of approximate importance to our operations:

  • Upper Yellowstone Basin Inside and Upstream of YNP: 109%
  • Upper Yellowstone Basin Downstream of YNP: 107%
  • Madison/Gallatin Basin Inside YNP: 90% 🙁
  • Madison Basin Outside YNP: 89% 🙁
  • Gallatin Outside YNP: 101%
  • Jefferson (Impacting the Missouri R.): 97%
  • Helena Valley (Missouri R.): 106%

As you can see from the above, we’re near or slightly above normal for two out of three of our critical basins. There’s definitely still some improvement needed in the Madison-Gallatin, especially for you Firehole fanatics.

Still, things have improved substantially of late, and we’re hoping they keep improving.