October Fishing on the Ruby River

October weather, stream flows, and summary

The Ruby River originates in the high elevation backcountry in Gravelly Mountains near the Montana-Idaho border. This rugged beginning is fitting for a river that, for most of its reach, flows through private property and is very difficult to access. Two distinct sections exist on the Ruby River: above Ruby Reservoir and below Ruby Reservoir. 

Above Ruby Reservoir the only accessible water is the river when it flows in Beaverhead-Deer Lodge National Forest. During October this section can fish, it can also be in winter mode—cold water and few hatches. If early October sees sustained weather colder than 40 degrees on average, the uppermost sections of the Ruby River is not an ideal option, leaving the Ruby River downstream of Ruby Reservoir as the best choice. 

And, it is great fishing…if access is gained or anglers are willing to cover some ground walking-and-wading. However, the Ruby River from Ruby Dam downstream to its confluence with the Beaverhead River near Twin Bridges is over 50 miles of thick brush covered banks, deep holes and pools, and lined with private landowners who take pride in keeping anglers off the river. Even with the low stream flows of October, walking-and-wading anglers need to be prepared to wade chest or neck deep to avoid trespassing. 

Because the Ruby River begins high in the mountains of southwest Montana, weather in October runs the gamut. With days of sunshine and highs in the 70s to blizzards and highs in the teens, it is best to prepare for changing weather. Average daily high temperatures hover around 50 degrees F. There is slightly more precipitation in October than September with an average of 1.3” and the possibility of snow increases substantially with 2” of average accumulation in the higher elevations. Quality fishing opportunities can occur in these variable weather conditions, but in October often the lousiest weather produces the best fishing. 

Blue Winged Olives (BWOs) are the primary hatch of October. A few October caddis are spotted but they are not consistent and emerge in small numbers, usually one or two at a time compared to the thousands of insects during a BWO hatch. 

Streamer anglers can find aggressive brown trout, especially on the river downstream of Ruby Reservoir. Terrestrials may be an option early in the month, but by mid-October one or two few cold fronts have passed through the drainage, causing several nights of heavy frosts, killing off nearly all of the grasshoppers. 

Streamflows are consistent and clear throughout the river’s length and water temperatures are rarely too cold or too warm, creating an ideal month for dry fly fishing, subsurface nymph fishing, and fishing streamers. If only access were not so darned difficult, the Ruby River in October would be the perfect Montana fly fishing river. 

October fishing: what to expect

October weather on the Ruby River can vary from day to day or hour to hour. Because of the inconsistency of weather on the Ruby River, the hatches can be sparse or thick, the brown trout can be aggressively attacking streamer patterns or not, plus the challenge of gaining access or risking being caught trespassing, fly fishing the Ruby River in October is equal parts enjoyment and endeavor. 

Hatches can be strong or they can be sparse. Fishing in cold, rainy, or snowy weather may not be what you find as enjoyable but armed with quality gear and a good attitude it just might pay dividends.

Sun, rain, and snow can all happen on the same day. The worst weather can create the best fishing conditions as Blue Winged Olives (BWOs) tend to hatch in rainy or snow weather. Brown trout, especially large brown trout, are inherently more sensitive to bright sunshine in the fall, so the shorter days—less direct sunlight on the water—means more active brown trout. 

A typical day fly fishing the Ruby River in October can begin at a reasonable hour. For the dry fly angler, the need for an early start is gone because if BWOs hatch they will begin around mid-morning or late afternoon. Large brown trout may be active early, but the sun rises between 7 and 8 AM most mornings in October so even for the hardcore streamer angler, early starts are not crucial. Tandem two-fly nymph rigs still catch plenty of fish in October, but October is the month for streamer and dry fly anglers. 

Olive, black or brown streamers are the go-to choices for October trophy-sized trout. Favorite tactics include dead-drifting a large streamer below a strike indicator or dragging a large streamer off the bank or through a deep run or pool. Many anglers will also trail a smaller nymph such as a size 16 or 18 mayfly nymph, creating a two-fly rig designed to entice a big brown trout or catch a selective rainbow or brown trout.

Dry fly anglers can also delight as hatches of BWOs are a common occurrence. When conditions line-up appropriately, typically a forecast for light rain or snow flurries coupled with low winds, Ruby River trout feed actively on hatching BWOs. October caddis hatch sporadically on the Ruby River this month as well, but most dry fly anglers will pursue BWOs. 

Where to find October trout on the Ruby

Similar to September, trout on the Ruby River in October follow the available food source. With the exception being brown trout are more aggressive and actively seek out prey. 

Covering water with streamers is a proven tactic on the Ruby River, but sometimes challenging due to private property. Therefore thoroughly fishing tandem nymph rigs through many of the deepest holes is always a good idea. Focus on the deep water in many of the Ruby River’s bends and pools, behind or in front of structure, or any place that can provide cover from predators or fast currents. Nymphs—mayfly, caddis, and stonefly nymphs and midges, are active in the Ruby River year-round. Unless a hatch of Blue Winged Olives (BWOs) is strong, trout will be found in subsurface lies. 

If sunshine is bright and strong and the air temperature hovers near 60 degrees F or higher, consider fishing terrestrials. Trout will expend vital energy and take the risk from deep cover because a morsel as large as a grasshopper, ant, or beetle may not pass by again that day or that season. Fishing grasshoppers in October is a rarity but it does happen. 

As the month progresses hatches of BWO mayflies can increase and brown trout grow even more aggressive prior to fall spawning. BWO nymphs can be found throughout the river. When a strong hatch occurs, look for trout in slower currents and “softer water” such as the inside of river bends, seams behind rocks, and slower runs below riffles. 

On the Ruby River trophy-sized brown trout can be found in the usual predator hangouts—deeper water near shallow water, hiding near structure or along the many rip-rap banks on the Ruby River, or along an undercut bank. Many brown trout will begin to spawn in October. These spawning fish may be found on their redds on shallow gravel bars. Please avoid targeting spawning trout when they are encountered.

October caddis are found in the Ruby River, but rarely are adults seen fluttering in the air. Unlike a river that is easily float-fished, fishing October caddis on the Ruby River is challenging. While float fishing a larger river, an October caddis floated over miles and miles of trout habitat can be successful. On the Ruby River because walking-and-wading is challenging, fishing October caddis on the Ruby River is not very practical. 

Important October hatches

October hatches on the Ruby River can be strong, causing many fish to rise to the surface. However, it is important to differentiate between the section above Ruby Reservoir and below Ruby Reservoir. Above the reservoir the most of the river flows through private property, so anglers mostly fish the river in Beaverhead-Deer Lodge National Forest. By mid-October winter this section of river will see hatches of Blue Winged Olives (BWOs) mayflies and midges. These hatches will occur during the warmest part of the day, typically between 1 and 3 PM. 

Downstream of Ruby Reservoir, hatches of BWOs are most consistent, with emergence occurring from mid-morning well into the afternoon. Midges hatch in this section as well as October caddis. However, BWOs are the primary action from Ruby Dam to the river’s confluence with the Beaverhead River near Twin Bridges. 

From its headwaters to its confluence with the Beaverhead River, the Ruby River is home to a healthy population of mayflies, caddis, midges, and some scuds and sowbugs. These insects are active year-round, so even if the insects are not hatching, the nymphs are available to trout. 

In October the emergence of fall Blue Winged Olive (BWOs) mayflies is the primary hatch. These small mayflies can hatch on any day during October. Overcast, rainy or snowy days see the strongest emergence. Ranging in size from 16 to 22, these mayflies are slightly smaller than their springtime cousins. Fall BWOs emerge by late-morning or early afternoon and provide a few hours of dry fly fishing opportunities.

October caddis also hatch on the Ruby River, but only below Ruby Dam. These bugs may be large in size—about size 8—but their hatch is sporadic at best. During any day of angling in October only a few October caddis may actually be seen fluttering in the air but committing to a large dry fly can bring the occasional opportunistic trout to the surface. 

Ruby River fly box for October

BWO dry flies sizes 16 to 22

BWO emergers sizes 16 to 20

BWO nymphs sizes 16 to 20

Midge larvae and dries in sizes 18 to 22

October caddis size 8

Crayfish patterns sizes 2 to 8

Sculpin patterns sizes 2 to 6

Streamers in yellow and brown combo, or black or brown sizes 2 to 6