May Fishing on the Ruby River

May weather, stream flows, and summary

The ability to fish the Ruby River during the month of May varies from year to year and week to week. Even with Ruby Dam, stream flows below the dam can be flowing fast and high, creating very difficult fishing conditions. However, if snowmelt run off is delayed and stream flows above and below Ruby Reservoir remain low enough, strong hatches of caddis can provide exceptional fishing. 

In most years, stream flows rise above 200 cubic feet per second (cfs) by the first week of May. Above and below the reservoir, fishing can still occur at these flows, but access is challenging. By the beginning of the second week of May flows are typically 300 cfs, which makes walk-and-wade angling basically impossible. At flows above 300 cfs the river is bank-full and the predominance of private property on the Ruby River makes getting around the river’s thick willow-lined banks an insurmountable feet without trespassing.  

It is rare that windows of fishable conditions occur in May on the Ruby River. Because stream flows below Ruby Dam are regulated, it is very rare that once they rise above 300 cfs, that they drop below 300 cfs. Above the reservoir, if a prolonged cold front causes snowmelt runoff to subside for a few days, some Mother’s Day caddis hatches can occur, but the weather must line up perfectly for river conditions to allow for stream flows and clarity to be conducive for feeding fish. 

May on the Ruby River is the wettest month of the year with over 2” inches of rain and a 1” of snow. Hours of sunlight increase to almost 15 hours by the end of the month. Daily high temperatures climb considerably throughout the month from a cool 55 degrees F early in May to nearly 70 degrees F later in the month, thus helping to speed runoff. 

The first two weeks of May serve up the greatest opportunity for fishable conditions. Caddis can hatch in abundance during a fishable window and the dry fly fishing can be exceptional. The ideal scenario for this to occur is daytime highs not above 70 degrees F and nighttime lows not above freezing. If this weather pattern holds for several days, on the river above the reservoir stream flows may drop and clarity improves, whereas on the river below Ruby Dam, regulators have to drop the outflows from Ruby Dam below 300 cfs. 

A few public access sites exist on the river below Ruby Dam, but when stream flows are above 200 cfs walking-and-wading and avoiding private property is difficult, and when stream flows rise above 300 cfs avoiding private property is impossible. 

May fishing: what to expect

Because most of May stream flows above and below Ruby Reservoir are above 300 cubic feet per second (cfs), fly fishing the Ruby River is downright difficult. The river is often high and fully in its banks. Because most of the Ruby River is surrounded by private property, access is challenging. 

However, if the weather becomes unseasonably cold, stream flows could drop. But, for a strong caddis hatch to occur, temperatures must climb above 50 degrees F. The best window of ideal water temperatures is also reliant on rising air temperatures. This also means snowmelt runoff can begin, making the opportunity to fish a caddis hatch on the Ruby River less likely than winning in Vegas by betting it all on black. 

If weather patterns and stream flows align and fishing is able to occur on the Ruby River, target slower banks, back-eddies, and foam lines around structure. If caddis are hatching use a tan or grey colored caddis dry fly in sizes 12 to 16. Various mayfly, caddis, and stonefly nymphs fished as two-fly weighted rigs dead-drifted or slowly stripped will pick up fish as well. 

On cloudy days emergences of Blue Winged Olive mayflies can occur, but the prospect of a strong hatch of caddis is what anglers hope for on the Ruby River in May. For dry fly anglers, time spent watching the weather, stream flows and being able to drop other responsibilities on short notice can result in great fishing.  

Before runoff commences in earnest, early May can also be a good time to target large fish using streamers. Slowly stripping, dragging, or dead-drifting streamers through some of the deeper runs and pools can yield some of the largest fish of the angling season. 

Where to find May trout on the Ruby

Finding trout on the Ruby River in May depends on the condition of the river. If the river drops and clears and a fishable window occurs, most fish will be found near bank-side structure and foam lines created by mixing currents or other structures. In these slower waters look for rising trout. 

During a hatch of caddis or BWOs target slower currents, eddy lines, and seams behind rocks. If a caddis hatch is thick do not ignore foam lines and back eddies because on the Ruby River the abundant caddis adults can stack up in these eddies and trout will follow, goring themselves in the many foam lines that are prevalent on the Ruby River. 

If a hatch doesn’t occur but fishable conditions happen, target slow eddies, foam lines, and any soft water near structure with subsurface nymphs. Trout will feed voraciously during May if stream flows drop below 300 cubic feet per second, but they will be in lies where they can enjoy access to food floating by without spending too much energy swimming in heavy current. 

Important May hatches

Hatches of caddis and Blue Winged Olives (BWOs) mayflies can occur on the Ruby River in May. Appropriately named the Mother’s Day caddis hatch because it occurs around Mother’s Day, the prospect of fishing this hatch  relies on day-to-day conditions. As the water temperatures climb to 50 degrees F, caddis may hatch on sunny or cloudy days and can provide some exciting dry fly fishing. 

BWOs will hatch in abundance on cloudy, rainy days but on sunny days might only hatch in small numbers. 

Ruby River fly box for May

Light bodied caddis dry flies size 14 and 16

Caddis pupae size 14 and 16

BWO dry flies size 16 and 18

BWO emergers size 16 and 18

BWO nymphs size 16 and 18

Stonefly nymphs in brown and black sizes 10, 8 and 6

Sculpin and streamer patterns—white and black—sizes 6, 4 and 2

White olive streamers in size 2 and 4

Brown and yellow woolly buggers sizes 2 through 6