Time: 10:30AM – 3:00PM
Location: Below Gross Reservoir
The long range forecast projected rain turning to snow and cold temperatures beginning on Tuesday, October 30. Monday on the other had was expected to be gorgeous with highs in Denver peaking in the upper seventies. This could translate to only one thing; an opportunity to sneak in a day of autumn fly fishing before wintry weather predominated. Perhaps this would be my last day of fly fishing in 2018.
But where should I invest my scarce amount of remaining nice weather equity? I scanned the stream flows, and of course the first drainage that I checked was South Boulder Creek below Gross Reservoir. The water managers were famous for making dramatic shifts in flows on the small tailwater west of Golden, and late October 2018 was not an exception to this tendency. My last visit to South Boulder Creek was on October 19, and I enjoyed an exceptional day, while the flows were a mere 14.4 CFS. The current DWR chart displayed a vertical rock wall for 10/24/2018, when the valve was opened to release 96 CFS. A dramatic change such as this caused me some concern, but it was five days ago, and I concluded that this allowed ample time for the stream residents to acclimate. I decided to give it a go.
I got off to a reasonably early start; and after I arrived at the trailhead, assembled my Orvis Access four weight and hiked down the path, I was in a position on the stream prepared to make my first cast by 10:30. The air temperature was in the mid-fifties, and the stream flow was indeed multiples higher than my previous trip. In fact the places were I was able to cross the creek were limited to wide shallow sections, and these were minimal within the predominantly narrow canyon environment.
Because of the higher flows akin to spring conditions, I opted to begin my day with a size 8 yellow fat Albert, beadhead hares ear nymph, and ultra zug bug. The first two pockets did not produce, but then I positioned myself near the middle of the creek and initiated some drifts through a prime deep run along the north bank. On the third pass a respectable South Boulder Creek brown trout pounced on the ultra zug bug, and I was very pleased to score my first fish of the day. I continued to prospect the quality run with across and downstream drifts, and I was pleasantly surprised to land five additional brown trout in the nine to eleven inch range. What a start to my day! Perhaps the elevated flows were not so bad after all, and the preponderance of brown trout relieved my fears of encountering mostly lockjawed spawning fish.
I wish I could report that this pace of success continued through my remaining time on the stream, but that was not the case. When I cast to the productive run three successive times with no resulting action, I departed and continued my upstream progression. Between 10:45 and noon I incremented the fish counter from six to ten, so clearly my catch rate declined; however, I remained quite pleased with the 1.5 hours of morning fly fishing. The yellow fat Albert began to distract the trout in the next several pools, and a string of refusals was ample testimony. I concluded that the fly was too large, and I converted to a size 12 peacock hippy stomper. The smaller foam attractor was an improvement, and it accounted for a few fish during the last hour before lunch.
After lunch I resumed my quest for South Boulder Creek trout, and I recorded quite a record of success. The fish count zoomed from ten to thirty-six, before I ended my day at 3PM. Although the three fly combination yielded fish at a steady rate after lunch, I sensed that I could improve my success rate, so I experimented with several fly exchanges. I removed the ultra zug bug and replaced it with a size 20 soft hackle emerger. This was an attempt to match a blue winged olive hatch or an emergence of small black stonefles. From past experience I knew that the small stoneflies were present on South Boulder Creek in the late October time frame. While the soft hackle emerger was on the line, it failed to yield a singe fish, but the hares ear became a favorite target.
Twenty minutes of no response to the soft hackle emerger caused me to once again make a change. This time I selected a size 14 iron sally from my fly wallet, and I positioned the heavier fly with the coiled wire body in the top position and moved the hares ear to the point. The hippy stomper, iron sally, and hares ear maintained their place on my line for the remainder of the afternoon, and they generated the most success.
Unlike my last outing at 14 CFS when upstream casts proved effective, the best approach on Monday was across and downstream drifts. The brown trout could not resist attacking one of the nymphs, as they began to swing at the end of the run, and many of my netted fish were victims of this tactic. Four rainbows joined the mix of catches, and they emerged from faster riffles of moderate depth, and the iron sally was their preferred food source. The hippy stomper was not purely a strike indicator, as it contributed quite a few respectable cold water fighters to the fish count.
By 3PM I reached a section characterized by fast chutes and whitewater, and the south canyon wall blocked the sun thus creating shadows over the entire stream. Tracking the hippy stomper became challenging and the catch rate plummeted, so I called it a day and made my exit hike. The air temperature remained quite comfortable, and climbing the steep path out of the canyon made me wish I had removed a layer or two of clothing.
In summary I landed thirty-six trout on a gorgeous fall day on South Boulder Creek. Five of the netted fish were rainbow trout, and as usual the rainbows were larger on average than the brown trout. Eight of my catch crushed the hippy stomper, four were duped by the ultra zug bug, six nabbed the iron sally, and the remainder snatched the hares ear. The higher flows made it more difficult to determine fish holding locations, which was a relatively easy exercise at 14 CFS. Counter balancing this factor was the relative ease with which I could approach fish holding lies, and the reduced level of stealth required.
If this was my last outing of 2018, it was a solid final episode. I suspect, however, that I will tally a few more days before my enjoyment of fly fishing is more that offset by the discomfort of cold hands and feet.
Fish Landed: 36