For the purposes of snowpack analysis and water management, the “water year” begins in mid-fall with the onset of winter at the higher elevations. Such a calendar is useful in the description of the angling year as well.

Winter


By the conclusion of the brown trout spawn in early November,  colder nights and shorter periods of daily solar radiation cool the water and riverbed of the Arkansas River, diminishing daily activity of aquatic insects and slowing trout metabolisms. 

From this point until mid-February, the dearth of bugs drifting on the current as part of their life cycle, coupled with cold water and frequent morning flows of slush, makes fishing on the Arkansas an early afternoon game best played on the nicest of days.

Among the diversity in orders of aquatic insects that inhabit the Arkansas River, the primary active ones in the deep winter months of late November, December, January and early February are the dipterans – specifically midges. 

One can actually find a 2 p.m. surface feed at this time of year when a January thaw or similar event raises water temperatures, and clusters of adult midges may be sufficiently concentrated in back eddies beneath warm cliff faces to bring fish up from the bottom. 

Far more common, however, is a reliance on midge larvae or pupae fished deep in or adjacent to winter holding water. 

A check of fish stomach contents during such warm winter afternoons will normally reveal a concentration of these tiny immature forms (size 20-24) but will often be supplemented by apparently random food from other orders entirely. 

The diverse nature of the Arkansas River aquatic insect population, coupled with the turbulence of its steep flow and the effects of ice or slush on the substrate, means that at any given moment it is entirely possible for a trout to encounter a wayward golden stonefly nymph, a dislodged caddis larvae or a struggling immature mayfly. 

For this reason, we strongly recommend use of weighted attractor/imitator flies in a multi-fly rig as a means of driving one’s midge patterns into the depths. 

Arkansas River trout are opportunistic by nature and necessity. Playing into that dynamic is much more effective than a narrow reliance on midge imitation coupled with in-line weight.

Spring


If there is a time of year that truly distinguishes the Arkansas River from other freestone fisheries in Colorado, it is spring. 

This does not refer to the leafing out of trees, a cessation in snowfall or the emergence of bears from their dens. 

Rather, “spring” refers specifically to the inception of a series of events in the life cycles of various aquatic insects that corresponds with an incremental warming of the river. In essence, fish begin to get hungry and there is a greater variety of food for them to eat.

• Stonefly nymphs – The Arkansas River is home to a variety of stonefly species, the most prevalent of the larger ones being golden stoneflies. 

Beginning in mid-February, as golden stonefly nymphs grow through instars of their development, they experience periodic molts wherein they shed their exoskeleton to accommodate new growth. 

During these times, they emerge brightly colored like a snake recently shed of its skin. 

This, coupled with a propensity for becoming dislodged while extricating themselves from their husks, makes them very vulnerable to predation during these times and thereby a welcome large serving of early season protein for trout. 

It is difficult to tell whether a golden stonefly molt is underway, but they transpire frequently enough that their presence in the water column is always plausible. Fish will take advantage of these large nymphs throughout the year, but especially when the only alternative is small winter midges.

• Caddis larvae – The Arkansas River is home to about 50 species of caddis, meaning that from late March into October there is almost always some form of caddis in the air. 

However, beginning in early March, free-living (uncased) caddis larvae go through periodic larval drifts. 

Like the stonefly nymphs, these events tend to take place in the lower light of morning and cannot be detected by a mere visual inspection of the river. 

Pumping stomachs or seining the current will reveal these bugs, or one can fish a cream, beige or green caddis larvae behind the stonefly nymph to determine if they are present.

• Blue wing olive mayflies – Beginning in mid-March, and hence referred to as the “St. Patrick’s Day Hatch,” the baetis emergence takes place on cloudy, damp, cool days from around then until runoff, producing the first real dry fly fishing of the year and creating the metabolic event for brown trout that drives them from their winter holding water into the pocket- and edgewater feeding lies for which they are most appreciated. 

Transpiring from early to mid-afternoon, the baetis activity consists of daily drifts of the mature nymphs that result in an actual hatch when atmospheric conditions are supportive. 

Regardless of the weather, however, one can count on this nymphal drift to move trout into fast and shallow riffly water, where the nymphs reside in greatest numbers, and to produce some aggressive and consistent fishing as a result. 

Subsurface emerger patterns like the RS-2, Barr Emerger and Juju Baetis fished a foot below the surface in this type of water will represent the drifting nymphs. 

If conditions support a hatch, one will find fish porpoising for surface emergers toward the heads of pools and blatant open mouths breaking the surface for adult mayflies in the slower mid-sections and tailouts.

• Brachycentrus caddis – Of the many caddis species that inhabit the Arkansas, the brachycentrus has historically produced the most prolific hatches. 

Beginning in mid-April (think “Tax Day”) in Cañon City and progressing upstream through mid-May as the river warms, the spring caddis hatch serves up a daily banquet of bug meat to trout that are fattening up for spring runoff. 

At times described as “the blizzard hatch,” the emergence can become so thick that fishing can become difficult. 

As a result, many anglers try to focus their efforts on the leading or trailing edge of the hatch rather than at its epicenter. 

Tied to an early afternoon water temperature of 54 degrees, this hatch is associated with sunshine and warmth, a good counter to the supporting conditions for the previously described hatch of the blue wing olive mayfly. 

Though the intensity of the hatch varies from year to year depending on conditions, it is for many Colorado fishermen the event that sets the season in motion.

Summer


For the Arkansas River fishery, summer can be defined as that period from the inception of runoff in late May until fall flows are achieved and water temperatures begin to cool, typically in the week or so following Labor Day. 

While runoff presents a set of challenges for fish and fishermen alike, once flows begin to subside in later June, summer provides some of the most consistent and enjoyable dry fly fishing of the year.

• Stoneflies – Of all the hatches on the Arkansas, perhaps the least experienced by anglers are the various stonefly hatches that occur during high water in June. 

These are typically big bugs that emerge onto shore in low light conditions following an incomplete metamorphosis to maturity. 

Since high water forces most browns into velocity shelters tight along the shoreline, the stonefly nymph is forced to crawl through a gauntlet of competitively hungry browns to reach the shoreline and adulthood. 

One needn’t wear waders to fish this hatch; some tennis shoes and a short leader are all that’s needed to work stonefly nymphs or dries right along the edge of the river where most trout are holding. 

Early morning and late in the day are the best times for this method of fishing. 

• Pale morning duns, yellow sallies, caddis, hoppers … from late June through August, there is a daily supply of mayflies, small stones and caddis that provide great afternoon or evening dry fly fishing on the Arkansas. 

Many anglers fish two of these dry fly representations in tandem, mimicking the emergences of multiple orders of insects with every cast. 

While the bright light of day demands a certain adherence to close imitation, summer evenings offer the opportunity to pull big browns from ambush lies with outsized stimulators, parachute madam x patterns, foam bodied hoppers, ants and other terrestrials. 

Perhaps more than any time of year, this is when one can simply read the structure along the shoreline and fish big buggy patterns into the pockets that make up the majority of summer brown trout habitat.

• Streamers – The Arkansas River has a very limited population of baitfish, primarily dace and young suckers. 

A far more prolific vertebrate food supply comes in the form of brown trout cannibalizing their young. 

While some might find taking advantage of such a predilection to be abhorrent, the imitation of small fish with streamer patterns, especially when thrown toward shore from a boat, can be an extremely effective summer tactic for brown trout.

Fall


Call it Labor Day to Veterans Day, the fall fishing on the Arkansas is generally some of the most pleasant one will find anywhere with fish willing to take imitations of mayflies and midges, as well as stonefly nymphs, hoppers and streamers. 

The skies are generally clear, the atmosphere calm, foliage colors riot along the river and on the higher peaks, and a distinct decline in fishing and boating pressure create the solitude anglers crave nearly as much as they do trout.

• Blue wing olive mayflies – This hatch resumes in the fall, though full-blown surface feeding on adults is often limited by the predominantly sunny skies. 

Daily afternoon drifts of mature nymphs, however, create consistent shallow subsurface feeding, a phenomenon that is almost as fun as true dry fly fishing and, in the case of this species, a lot more common.

• Midge pupae – In a manner similar to the drifting of mayfly nymphs through fast pocket water in the top foot of the water column, a small midge pupae (20-24) trailed behind a weighted nymph in the morning hours will reveal strong populations of brown trout working water that one might normally deem too fast for them. 

While the frost on the shoreline at 8:30 a.m. might predispose one to focusing on rainbows or another cup of coffee, the fall water temperatures drop slowly from summer, allowing browns to respond to their biological imperative to put on weight for winter, despite the chill that keeps many anglers off the river until noon.

Few rivers in Colorado can boast the biological diversity of the Arkansas River ecosystem. 

In truth, this account touches on only the most predominant of the myriad insect species and life cycle components that make up a local trout’s diet. 

There remains significant room for discovery and innovation in this regard, something that keeps so many of us coming back to the Arkansas year after year.

Greg Felt is a fishing guide and co-owner of ArkAnglers.