Time: 10:30AM – 3:00PM
Location: Below Gross Reservoir
The star of my fly fishing outing on September 10, 2021 on South Boulder Creek was the sunk ant. My history with the sunk ant is rather brief relative to my fly fishing lifetime, but it has recently climbed my fly rankings as a promising producer. Click on the sunk ant link to read more about my history with sunken ants, and you will also find the source of the pattern I choose to deploy.
But I am getting ahead of myself. If you read my previous post on Pine Creek, you know that my attempt to return to South Boulder Creek for a fourth time this summer was thwarted, when the Denver Water powers reduced the outflows from Gross Reservoir on Wednesday from 95 CFS to 15 CFS. This spooked me, because at the time of my decision on a fishing destination, the downward spiral on the graph was at 65 CFS, and I was uncertain how low it would go. I am also leery of visiting a stream after a dramatic change in flows, as it takes some time for the stream residents to adjust to their modified environment.
The DWR graph eventually settled at 11.1 CFS and remained at that level Wednesday through Thursday. On Thursday evening I searched through my South Boulder Creek blog reports on this site, and I found two from October 2017 that described my experience, when the flows trickled at 9.3 CFS and 10.5 CFS. I actually enjoyed double digit days in both instances, and this encouraged me to make the drive to South Boulder Creek on Friday morning.
The air temperature upon my arrival in the parking lot was 71 degrees, and I was tempted to pull on my wet wading pants and wading socks; however, historically me feet get numb at the small tailwater, even when I wear my waders, so I adhered to the wader approach, even though I knew I was in for a hot hike. I strung my Orvis Access four weight and descended the steep path to the edge of the creek; and, sure enough, the stream was flowing along at a reduced level from what I became accustomed to. Bare rocks and dry streambed characterized the view, but even at 11.1 CFS the creek was the size of some of the high mountain streams that I recently explored.
By 10:30AM I was perched along the creek ready to pursue the wild denizens of South Boulder Creek canyon. My blog posts highlighted the success of beetles and ants, and I was present on the creek one month before my 2017 visit, but I decided to experiment with a Jake’s gulp beetle first. The size 12 foam terrestrial attracted attention in the early going, and I landed three nice brown trout, before the trout seemed to scorn my offering more frequently than they ingested it. On one of the 2017 posts a black parachute ant was on fire, so I exchanged the beetle for a size 18 black ant with a pink wing post. The low floating bug duped a pair of nice fish, but it also floated unmolested through some very attractive smooth pools. As my morning evolved, I spotted five yellow sallies, as they slowly glided skyward toward the streamside trees. Could this be a hot menu item?
I once again swapped flies and replaced the ant with a size 16 deer hair yellow sally. The move paid quick dividends, and I landed five more trout to elevate the fish count to ten, as I found a nice flat rock on the south bank and chowed down with my lunch. Several of the trout attacked the yellow sally aggressively, when I twitched it across some shallow riffles, so movement was part of the program during the yellow sally phase.
After lunch I suffered a lull, and I no longer witnessed natural yellow stoneflies in the atmosphere, so I once again changed the game plan. I knotted a peacock hippie stomper to my line under the assumption that it was close enough to a green drake, that it would attract attention, if western green drakes were still active. A couple of aggressive feeders snatched the foam attractor, but refusals were also part of the equation. The foam hippie stomper is large enough to support a dropper, but I knew that a beadhead would create too much of a disturbance in the low and clear conditions, so I opted to tie on a sunk ant on a 1.5 foot leader. What a move this turned out to be!
For the remainder of the day I progressed upstream with the dry/dropper combination and boosted the fish count from ten to thirty-four. Friday afternoon represented the type of fishing I thoroughly enjoy. I fluttered casts to all the likely pools, pockets, riffles and runs; and more often than not the trout cooperated. The hippie stomper remained as the top fly for much of the time, but I also cycled through a parachute green drake, green drake comparadun, and user friendly green drake. Each green drake produced a few trout, but the South Boulder Creek cold water trout were not locked into green drakes with the same fervor that they displayed on my three prior trips. I returned to the hippie stomper after the green drake experiment, and it accounted for four eats, but the real star of the show was the sunk ant.
I was pleasantly surprised by the effectiveness of the shallow drifting sunken terrestrial. I was concerned that the fish would gravitate to the large surface offerings and ignore the small ant, but this was not the case. In several instances an above average trout attacked the ant, almost as soon as it entered the water, and this reaction always surprises me. Quite a few times I cast the dry/dropper to the top of some very clear shallow riffles, and near the tail I spotted a swirl and set the hook under the assumption that the trout grabbed the surface fly only to discover an ant embedded in the lip. Clearly a tumbling sunken terrestrial was not an uncommon occurrence in South Boulder Creek.
By 2:30PM the sun was bright above and the heat in the canyon was oppressive. The trout seemed to take a siesta, and this angler felt like doing the same. My fish count was already locked on thirty-four, and the most recent fish came from deep slots that bordered oxygenated water next to structure such as large boulders. Quite a few small caddis flitted about on branches along the bank, so I forsook my treasured ant and replaced it with a size 16 deer hair caddis on a one foot dropper off the hippie stomper. I continued prospecting the double dry combination through some very attractive plunge pools and deep runs for another half hour, but the effort proved futile. At 3PM I surrendered to the heat and completed the hike back to the parking lot including the steep ascent at the end. I was a soggy piece of toast by the time I unlocked the tailgate.
Friday was another fabulous day on South Boulder Creek. On September 10 I was forced to work harder than my previous outings. During those day I simply knotted a green drake pattern to my line and enjoyed the outstanding success. Of course I needed to respond to the conditions a few times, as I rotated through my green drake styles, but the solution to the puzzle was rather apparent. Friday’s success required adjustments, as the day progressed. I began with terrestrials and then shifted to yellow sallies and eventually settled on green drakes and sunken ants. 11.1 CFS dictates cautious approaches and long delicate casts, but Friday proved that success can be found at relatively low flows, and sunken ants were part of the equation.
Fish Landed: 34