It started snowing at noon on Friday, April 18, and continued for about 24 hours. Since the storm pushed in from the east, the high country got some accumulation but the heavier snow seemed to fall in the valley itself. This is welcome moisture for irrigators and will green up the fields in the next few days. The river cooled a bit after weeks of unseasonably warm weather and the flows will probably bump up a little bit as the snow melts. It is not clear yet whether this storm will help a lot with snowpack and river flows but everyday that is cloudy and every new layering of clean, bright snow over the older dusty layers helps to sustain the snowpack further into the season.
The warm weather over recent weeks hasn’t helped the snowpack but it has worked its magic on the fishery. With water temperatures climbing and days getting longer we are seeing strong hatches of midges and blue-wing olive mayflies. The midges are a morning emergence and the mayflies are active in the afternoon. Also just getting underway is our annual brachycentrus caddis fly hatch. The next 3-4 weeks are when the Arkansas River trout population really puts on weight to sustain itself through the rigors of the coming snowmelt. It’s a great time to get on the river!
If you are on the water before 11:00 a.m., there will probably be active midges and fish feeding on them beneath the surface. The Arkansas is a steep and turbulent river and does not have many of the long slicks where trout will feed actively on adult midges. Generally, we approach this hatch by imitating the larva and pupa deeper in the water column. Whether fishing a nymph rig or dry-dropper, trailing a small zebra midge or other slender, striated pattern is a consistently effective approach.
It's not uncommon to see a lull in the late morning to early afternoon. But from 1:00 to 4:00 we are typically experiencing a regular blue wing olive nymphal drift. These nymphs typically reside in the substrate beneath well-aerated riffly water. Many of the mature nymphs will drift on the current in the afternoon. If the sun is bright, they may make their way back to the riverbed and wait for another day. If it is cloudy, and dark and damp in particular, many of the drifting nymphs will work their way to the surface. They often struggle with the surface tension, so the emergence from river bed to river surface can take some time and cover some distance. The bugs are particularly vulnerable to predation in that upper foot of the water column.
When fish are spotted actively feeding on spring afternoons, it is a good idea to spend a few minutes observing their behavior. If you see fish holding in relatively fast water and are seeing the flash of their midlines, they are probably feeding on the nymphs as they are beginning their drift up in the riffles. Often fish will get in front of a rock and “surf” the pressure wave that forms there. We typically use a dry-dropper or nymph rig with a weighted BWO nymph during this stage.
If it is cloudy and a true emergence is getting underway, you will likely see the backs and tails of fish porpoising. These fish are feeding on emergers in that top foot of the water column. At this point, we will usually go to an unweighted emerger behind an indicator or indicator dry fly. This may be the point to put an imitative dry-fly on and then trail the unweighted emerger behind that. The rise form will shift when the fish start keying onto the adult mayflies, transitioning from the porpoising feeding behavior to gentle sipping rises on the surface. Because the adult mayflies are often stuck for a while on the surface, waiting for their wings to stiffen up, the trout will pile up along seam lines or in big eddies and gently sip the vulnerable mayflies off the surface.
Now that we are in the second half of April, a third significant emergence will be added to the mix. The Brachycentrus caddis is a cased caddis that spends the majority of its life as an encased larva, filter-feeding out of the current. As it approaches the time to mature, it seals itself in its case and goes through a metamorphosis to become a pupa. This is a one-way change that prepares the caddis to hatch as an adult. When a pupa is ready, it simply needs the right water temperature to trigger the emergence. Typically, this is 52-54 degrees between noon and 5:00 pm.
The pupa secretes a small bubble of gas that acts as a buoyancy aid during the hatch. When the water temperature is right, the mature bug will “pop” out of the case and come to the surface very quickly. Unlike the mayfly, the quick ascent of the caddis pupa carries it through the surface tension easily and the moth-like tent-fold wings begin to flutter on contact with the air. They create a lot of commotion on the water and this generates a very different riseform from the fish. Look for big splashy rises on caddis as opposed to the gentle sipping one sees around mayflies.
On a fishery like the Arkansas River, where the elevation drops from 10,000 feet up in Hayden Meadows down to 4,500 feet in Canon City, one would expect to find 54 degree water at lower elevations in the spring before seeing it at higher elevations. As a result, the caddis hatch activity appears to migrate upstream over the weeks of the emergence. It will often start down in Canon City around April 15, be found at Cotopaxi around April 25, hit Salida about May 1, and be up in Browns Canyon and Ruby Mountain by May 7. Eventually, it gets so warm that the energy required to warm the river to 54 degrees above Buena Vista will also cause the alpine snow to melt, cooling the river again. The Brachycentrus caddis that live above Buena Vista typically hatch in late June after the runoff has passed.
The next three to four weeks are always a very dynamic period for the fishery. Spring weather can change quickly, causing water temperatures to change and triggering or pausing the various hatches. It can make for incredible fishing and also periods of complete perplexity. ArkAnglers is here to help! Our online fishing reports are updated regularly, sometimes hourly, to reflect the latest conditions, and we are always glad to take your phone calls and help you achieve success. We are eager to welcome you to our shops in Buena Vista and Salida, whether you need a new outfit or simply directions to public water. We also have a renowned guide service, with about twenty float and wade guides on staff. Our float trips will take you into water you could never access on foot and make for a memorable and rewarding day on the water. Our wade trips are the better instructional option, giving you the techniques and strategies that will serve you best on foot on your own.
Spring fishing on the Arkansas River is an annual ritual for so many Colorado anglers. We look forward to seeing you soon!