Runoff and Season Fishing Predictions Update

After a slightly heavy winter snowpack and a very cold and wet April that saw snowpack to increase to about 160% of normal in the Yellowstone River basin, spring sprang in earnest around May 5. With the exception of a window of cold weather last week accompanied by heavy snow in the mountains and a couple inches even in the valleys, May has been very warm and is forecast to continue to be warm

Runoff is now well underway on all waters. Even the Bighorn and Missouri are very high for the date. These are the only two fishable rivers in the region right now, but the lower Madison and some Yellowstone Park waters will come into play soon.

Current snowpack ranges from 104% to 151% in our operations area, so we’re set for high, cold flows and excellent water conditions this season, once runoff recedes. Runoff will be prolonged and high compared to most recent years, which saw below-normal snowpack. This will help a lot in late July and August.

All in all, there are few changes since our last update.

Predicted Clearing Dates and General Fishing Notes for Key Waters

The Yellowstone River Outside YNP: We expect the Yellowstone to truly drop into fishable shape during the first week of July, with Salmonflies at the same time. The river should have excellent flows this season, with the best dry fly fishing running from July 10-15 through Labor Day and good fishing thereafter depending on hatches. Yankee Jim Canyon should be fishable from around August 1 through Labor Day. There will be no repeat of last year’s low water-related closures. We anticipate the best water conditions here since at least 2014 except in late June.

The Yellowstone Inside YNP, the Grand and Black Canyons: Should drop into shape around July 4 and fish well through early October. Salmonflies will be on portions of this water through July, with the peak of the hatch around July 15-25.

The Yellowstone Inside YNP, Lake to Falls: This is going to be the best year on this water since the late 1990s. There’s a called shot for you. Cutthroat numbers here have been trending upwards for several seasons due to the aggressive lake trout suppression efforts in Yellowstone Lake as well as good spawns in recent years. I expect strong numbers of moderate-sized (12 to 18-inch) cutthroats from these good recent spawns as well as some true trophies (cutthroats to 24+ inches). Moreover, weather/water conditions will delay the fish returning to Yellowstone Lake after the spawn and will push them towards the banks where they are easier to spot and stalk. This water opens July 15 and I strongly encourage skilled anglers to ignore the Lamar Basin in favor of this water for the two weeks after the opener. It won’t be like it was in the “glory days” from the late 1970s through the mid-1990s, before the lake trout boom and subsequent cutthroat crash, but it should be very good for anglers who want to take a crack at the largest river-dwelling cutthroats in Yellowstone Park.

The Lamar Drainage: Slough Creek should become fishable around July 4, the Lamar and Soda Butte around July 10. We expect excellent water conditions on these streams this year, with some relief from the low water, crowded conditions, and overstressed fish of the past two August/September periods. I predict the most consistent (though not necessarily “best”) fishing on Slough Creek will occur in the last ten days of July, and on the Lamar and Soda Butte during the first half of August. Slough Creek is sometimes fishable right at the beginning of the park season, for a few days. This is unlikely this season.

The Firehole, Gibbon, and Madison: The Firehole will be at least marginally fishable on the park opener (May 27), though it will be high and tea-stained. It will be the only river that will fish well on this date. The fishing may be challenging if it is warm and rainy, as this will send a lot of the remaining snow into the river. Cold weather Thursday and Friday–which is forecast–will help opening weekend fishing as it will slow the snowmelt and pump out BWO hatches. The Madison will come into shape around June 1. and the Gibbon below Norris will drop into shape around June 5. The Gibbon above Norris will not be ready before June 15 and will be much better from July 10 onward. Good fishing on the Firehole will continue through June and will become day-to-day between July 1 and July 7, with cool temps necessary during this last week for good fishing. July 10 through Labor Day will see water temps too high for the Firehole to be fishable. The Madison and Gibbon below Norris Geyser Basin should fish well through July 4 and in the mornings through July. Cool weather in June might mean the Madison and lower Gibbon remain fishable at least in the morning through the summer this year. This is very unusual.

Gardner River and Tributaries: The mainstem Gardner downstream of Boiling River is always fishable from the beginning of the park season for fit anglers willing to handle very rough and physical walking and wading FOLLOWING A DAY OR TWO OF COOL, DRY WEATHER, WHILE BEING TOO HIGH AND DIRTY AT OTHER TIMES. This pattern will continue through July 1 this year, with the river fishable almost every day thereafter. The river will be fishable on a day-to-day basis from Osprey Falls to Boiling River after June 25 and for good after July 4. Above Osprey Falls, consistent fishing will not begin until after July 4 and maybe as late as July 15. The tributary creeks will come into play around July 1. The lakes will be ready by the opener, though Fawn will be difficult to access until June 20 due to the river and stream crossings required. Joffe Lake MAY be the only body of water across the north end of the park to be easily accessible, open to fishing, and fishing well on the opener. It depends on the day-to-day weather.

Small Streams: With the exception of those in the Firehole drainage (ready June 20 and good by July 1) and those in the Gardner Basin (see notes in the Gardner entry above), most small streams will not be fishable before mid-July and will be best in August and early September. This will be a good late summer for the small streams, which is when we most love to fish them.

Lakes in Yellowstone Park: Yellowstone Lake will be best before July 1 and should be fishable from the opener, though it will be very high. Lewis Lake will ice-out by the end of the first week of June and will fish best in the two weeks thereafter. There will still be a lot of snow on the banks to handle, however. Shoshone Lake will ice-out at the same time but will be difficult to access accept by boat until at least late June, due to snow on the trails. I dealt with thigh-deep snow on the trails to Shoshone on June 26, 2009, and there will likely be more snow this year. Smaller lakes except Blacktail (which opens July 3) will be ready to fish and accessible by June 10 and will fish best from this point through early July. See notes in the Gardner River entry for lakes in its drainage.

The Lower Madison below Ennis Lake: The heavy melt of the past week has muddied this water, which is unusual. It should clear suffciently to fish well with streamers, San Juan Worms, and big nymphs by May 20 and remain fishable thereafter.

The Missouri: Running high and hard, but even below the Dearborn the clarity is at least 18 inches. Flows should drop below the Dearborn this week, but overall flows may rise again in early June as Canyon Ferry Reservoir reaches full capacity. The Missouri is very, very big, but it is unlikely to ever get too muddy to fish and is fishing very well on deep nymphing rigs. I (Walter) have run five trips here in the past three weeks, with four more forecast for the remainder of May.

Private Lakes: The lakes (particularly the Story Lakes) are already in shape and fishing well. They should see normal conditions this year, with Story and Merrell fishing well into late June and Burns fishing through July.

Paradise Valley Spring Creeks: The creeks are not impacted by runoff. Fishing is best before mid-May and again from June 20 through July, then gets steadily better once more after September 15.

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