Hatches

The following is a general overview of the main hatches we see here in the Gunnison Valley throughout our fishing season (March through October). Some recommended fly patterns are included as well.

March through April (before run-off)
The main early season hatches consist of midges and the first mayfly hatch of the season – the Blue-Winged Olives (BWOs). The BWOs can hatch as early as mid to late March, depending on weather and water conditions. However, we normally see this hatch around mid to late April or so as water temperatures rise. Fish activity will increase in early spring when water temperatures rise over 40 degrees.

During the early season before run-off, trout will feed on midges, mayfly nymphs, and also large stonefly nymphs. You can fish a tandem nymph rig with a big stonefly nymph pattern and small mayfly nymph or midge trailing behind. Fish will also begin to chase streamers.

Midge (larva, emerger, adult):gray, black, olive, red, cream – sizes 18 to 24
BWO (nymph, emerger, adult):sizes 16 to 20
Stonefly Nymphs:20-Incher, Rubber Legged Stones, Golden Stones – sizes 6 to 8
Mayfly Nymphs:Barr BWO Emergers, Pheasant Tails, Copper Johns – sizes 16 to 20
Streamers:Muddy Buddy, Sculpzilla, Wooly Bugger – sizes 4 to 8

May through June (run-off)
Run-off can be difficult to predict and it varies each season based on snow-pack and weather. Typically, you can expect run-off to begin by late April or early May. Run-off conditions can last anywhere from four to eight weeks, but it could be more or it could be less. During run-off, there are some hatches of BWOs and caddis, and also some stoneflies, but these hatches are normally not fishable during this time due to the high water. You’ll also find rainbow trout spawning from late April throughout May, and it is best to leave spawning fish alone during this time. It’s a great time to fish the smaller creeks. The summer hatches will begin earlier on the small streams and provide great dry fly fishing opportunities.

June through August (after run-off)
We see peak insect activity and the best dry fly action during the summer months here in our part of the Rocky Mountains. You can expect good hatches of BWOs, caddis, stoneflies, Green Drakes, and Pale Morning Duns (PMDs). BWOs and caddis will hatch throughout summer.

The big Western Green Drake will begin to hatch in late June. This hatch starts in the lower part of the Gunnison River, just above Blue Mesa Reservoir. The hatch progresses up through the watershed and will eventually occur on the Taylor River and East River. The Drakes will continue to move up the Taylor River to the C&R (Catch-and-Release) section below the dam. The hatch is different every year and is very difficult to predict. It can take anywhere from two to four weeks to move from Blue Mesa to Almont and beyond. We can also see PMDs hatch just before, during, and after the Green Drake hatch. There have been many times when the PMDs have dominated. They are an important food source for trout during a large part of the summer.

BWO (nymph, emerger, adult):sizes 16 to 20
Caddis (pupa, emerger, adult):tan, olive, brown, black, yellow – sizes 12 to 20
Stonefly (adult):Salmon Fly, Golden Stone – sizes 4 to 8
Little Yellow Stonefly (adult):Yellow Sallies – sizes 16 to 18
Green Drake (emerger, adult):sizes 10 to 12
PMD (emerger, adult):sizes 14 to 18
Hoppers:tan, yellow – sizes 6 to 10

After the major summer hatches are complete, late summer brings hoppers. August is a great time to fish big hopper patterns. In general, terrestrials can be a food source from late July (and sometimes sooner) through August, and even into September.

Fishing dry-dropper rigs during summer can be very effective. This involves fishing a dry fly with a nymph or emerger dropped below it. You can also fish a hopper on top with a nymph below it (hopper-dropper rig).

September through October
Fall can be an excellent time to fish in the Gunnison Valley. The fall hatches are limited and can be more sparse as compared to the summer hatches, but the fish are active. There is a Gray Drake (also referred to as a Slate Drake or Slate Gray Drake) hatch which can start as early as late August and run through late September and into October. In addition, there is a good fall BWO hatch. These BWOs are very small, in the size 20 to 24 range, but they are significant. They will hatch from about late August through September/October. Trout will rise up and sip these BWOs from the surface.

Fall is also a good time to fish streamers and egg patterns. Brown trout and kokanee salmon spawn in the fall, and they will become very aggressive prior to spawning during mid to late September and into October. Streamers can be very effective during this time. Once the browns and kokanee begin to drop their eggs, rainbow trout will move in behind them and feed on the eggs. Egg patterns are effective during fall and straight through the winter months.

BWO (nymph, emerger, adult):sizes 20 to 24
Gray Drake (emerger, adult):sizes 12 to 14
Streamers:Muddy Buddy, Sculpzilla, Wooly Bugger – sizes 4 to 8
Egg Patterns:roe, chartreuse, cheese – size 14

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