June Fishing on the BigHorn River

June weather, stream flows, and summary

The Bighorn River offers consistently good fishing in June. However, there are some years when early June may be the only time when the Bighorn River’s clear and cold water doesn’t serve up consistent opportunities to target the river's 4,000+ wild trout per mile. 

If early June is a wild-card—with a 50-50 chance of being a winner—late June is surely to top the podium. Even in years with stream flows above 7,000 cubic feet per second (cfs) in early June, by the second half of June stream flows on the Bighorn River begin to stabilize or drop substantially. Hatches of Pale Morning Dun mayflies and caddis commence and the Bighorn River showcases its many exciting attributes. Because stream flows on the Bighorn River are regulated by Yellowtail Dam, an understanding of stream flows is crucial to success on the Bighorn River in June. 

Early in the month as snowmelt runoff in the Bighorn River’s headwaters in Wyoming and in Yellowstone National Park increases, inflows into Bighorn Reservoir increase as well. This causes the release of water below Yellowtail Dam. They are typically at their highest outflows in early June. By mid-June, outflows and the resulting stream flows on the river, drop to levels more suited for fly fishing.

During June, weather on the Bighorn River is often pleasant, yet with the possibility of substantial rain early in the month. Average daily highs in early June are in the mid 70 degrees F, but by month’s end increase to high 80 degrees F. Average daily precipitation also increases throughout the month, with the first two weeks of June seeing nearly half the potential of measurable precipitation compared to the last two weeks. 

Because the Bighorn River is ideally suited for floating and walk-and-wade fishing and home to over 4,000 trout per mile, ample opportunities abound to enjoy its quality fishing. In the second half of June hatches of Pale Morning Duns and caddis paired with an average trout-size of around 16 inches, the Bighorn River is a world-renowned destination for plenty of large trout. 

June fishing: what to expect

Fly fishing the Bighorn River in June can meet or exceed most angler’s expectations. However, it is crucial to understand how the fishing will take place. Simply put: if stream flows are over 6,000 cubic feet per second (cfs) the fishing is exclusive to float fishing and if flows are below 6,000 cfs floating and walk-and-wade fishing both become options.  

In most years in early June the river is likely to be high, with stream flows over 6,000 or 7,000 (cfs). There are years these high flows do not occur, but it is best to expect high flows through June 15th. High flows on the Bighorn River do not translate into lousy fishing, in fact for floating anglers with experienced boaters on the oars, the float fishing action on the Bighorn River can be exceptional.  

Two-fly weighted nymph rigs are the go-to rig in early June. Dragging or slowly stripped streamers can also catch some fish, but weighted worms, scuds, sowbugs, mayfly, and caddis nymphs fished in slower water are the preferred method for filling the net. At flows above 7,000 cfs, terrestrial worms are flushed into the currents during rising flows or rain events, as well as the high stream flows disrupt the small-sized cobble of the streambed, dislodging a variety of aquatic worms and insects. A successful rig for the Bighorn River in early June is a size 10 worm pattern and a size 16 bead head scud, sowbug, mayfly, or caddis nymph fished about 8-feet from a strike indicator on a 12-foot long leader. 

As flows drop by the middle of the month, Pale Morning Dun (PMDs) have a strong emergence. Look for fish to actively feed on emerging and hatching insects once flows drop below 6,000 cfs. At levels below 6,000 cfs wading anglers can begin to pursue these hatches. PMD dry flies and emergers in sizes 14 through 18 fished in riffles and shallow flats are preferred.

Caddis, and specifically tan-colored caddis, begin to hatch in the later part of June. These caddis range in size from 14 to 18, with most adults being size 18. Hatching in the numerous riffles and runs, tan-colored caddis are a primary food source for Bighorn River trout in late June. 

Where to find June trout on the Bighorn River

Where Bighorn River trout will be found in June depends on stream flows. For the first half of June flows traditionally can be high while by the second half of June flows will begin to drop and by the last week, they are often below 4,000 cubic feet per second (cfs), slipping right into prime dry fly range. 

In early June if stream flows rise above 6,000 cfs many of the river’s trout will migrate to feed in the softer water—inside bends, slower deeper runs below long shelfs, or slow currents of large eddys. During high flows or after a rain event, worms--both aquatic and land-based--can be flushed into the river. Many longtime Bighorn River locals know this and when this occurs the fishing of worm patterns is very successful. Flows over 8,000 cfs are very high and the river is running bank-full and fast, but an abundance of food is available to trout. Only very experienced floaters should float the Bighorn River at flows above 7,000 cfs. 

In early June, if the river has rising flows, target slow eddys, foam lines, and any soft water near structure with subsurface nymphs. Trout will be in lies where they can enjoy access to food floating by without spending too much energy swimming in the rising stream flows. Trout use these slower, mixing currents, as both holding and feeding lies. Two-fly subsurface nymph rigs can rack up numbers in these current seams.

If flows drop below 4,000 cfs and Pale Morning Dun (PMDs) mayflies or caddis hatch, look for trout in faster, shallow areas of the river. Target water with a stream bottom made of small rocks or pebbles or seams along banks or structure. 

Long, shallow flats are common on the Bighorn River. Many of these flats are covered in small rocks or softball-sized rocks. Although the rocks may seem small, they create plenty of structure and cover for trout. When stream flows are below 4,000 cfs and when PMDs and caddis are thick, these flats are often filled with trout rising to PMDs or caddis.  

PMDs hatch in mid-June on the Bighorn River. These hatches can be very strong and many of the river’s trout will move to shallow flats, riffles, and runs to feed on emerging nymphs or floating adults. Look for trout in faster currents along riffle corners and seams, medium-speed currents on shallow flats or long runs, and as the hatch wanes later in the day, look for eddys where PMDs adults may have accumulated.

Important June hatches

Hatches of Pale Morning Duns (PMDs) and caddis are the focus of anglers and trout on the Bighorn River in June. With the Bighorn River’s abundance of runs, riffles, and shallow flats and a stream bead of cobble-sized rocks and potholes, the river has ideal habitat for PMDs and caddis. 

Caddis, with most species being tan-colored, hatch in late June and last throughout the month. Emergences can be very strong. When they occur, trout have plenty of insects from which to choose, so making a good presentation is crucial. Most caddis on the Bighorn River are sizes 16 through 20. 

PMDs hatch in early June on the Bighorn River. River locals and loyalists relish the emergence of PMDs on this tailwater. Emerging out of riffles and flats, these size 14 to 18 mayflies create ample opportunities for floating and wading anglers. 

Yellow Sally stoneflies also hatch in June. Trout will consume the nymphs, but rarely do Bighorn River trout eat Yellow Sally adults. 

Worms—both aquatic and terrestrial based—are abundant on the Bighorn River. These worms do not hatch like mayflies or caddis, but after a large rain event or rise in streamflows, these worms are dislodged and become easy pickings for trout. 

Scuds, sowbugs, and crane flies are abundant in the Bighorn River, with sowbugs accounting for over half of a Bighorn River trout’s diet. Strictly subsurface, these insects are active throughout June and available to hungry trout. Oftentimes thought of as the same insects, a scud resembles a freshwater shrimp and a sowbug looks like a “rollie-pollie” bug. Even if they are different, a trout on the Bighorn River in May often gobbles-up a well-presented scud or sowbug. 

Midges are active year-round on the Bighorn River River and make-up a massive chunk of a trout’s diet. Fishing midge patterns is best done subsurface as part of a weighted two fly rig. 

Bighorn River fly box for June

Caddis pupae size 16 to 20

Caddis CDC emergers size 16 to 20

Caddis dry flies tan colored bodies in size 16 to 20; 

PMD dry flies size 14 to 20

PMD emergers size 14 to 20

PMD nymphs size 14 to 20

Yellow Sally nymph in sizes 10 and 12

Worms in sizes 8 through 14

Scuds in sizes 10 through 20

Sowbugs in sizes 10 through 20

Midges, especially Zebra midges in black and olive, in sizes 16 through 22

Sculpin patterns in sizes 2 to 6

Streamers in olive, black or brown in sizes 2 to 6