Time: 11:00AM – 3:30PM

Location: Below Gross Reservoir

South Boulder Creek 10/22/2025 Photo Album

What a day! October 22 is kind of late in the season for this fair weather angler, but the high in Denver was projected to climb into the seventies, and when I checked the two locations close to my intended fishing destination, the weather indicated temperatures in the sixties. I decided to pay an autumn visit to South Boulder Creek.

Source of Early Trout

The flows were reduced at 17 CFS, but I knew from previous experience that I fished successfully at 10 CFS. Low clear flows would dictate stealthy approaches, longer casts and light flies. I was prepared.

So Pretty

I arrived at the Walker Ranch Loop Trailhead, and I quickly geared up with my Sage R8 four weight. For clothing I wore a short sleeve high tech undershirt and my fishing shirt, but I loaded my backpack with my raincoat and a long sleeve Under Armour shirt. If I perspired excessively, I planned to change undershirts, before I began to fish.

Another Early Rainbow Trout

There were three cars in the parking lot besides my Telluride, but none of them were obviously fishermen. In fact, I never saw another angler during my entire time on the creek, nor did I encounter any on my hike to and from the stream. I had the entire small tailwater to myself. Perhaps the low flows scared away other anglers.

Shelf Pool

As I descended the trail to the creek, I heard the sound of heavy equipment operating to the west. Almost instantly I went into panic mode, as I envisioned the 17 CFS as a muddy mess from excavation taking place at the dam expansion site. You can imagine my relief, when I caught my first glimpse of the creek, and it was crystal clear.

Stealth Required

When I finally arrived at my chosen starting point, I concluded that I was perspired but not to the degree that I required a shirt change. I began my quest for South Boulder Creek trout with a solo peacock size 14 hippie stomper, and the dependable fly yielded three fish including a nice eleven inch brown.

Fine Rainbow Trout

After the early success, the trout’s interest in the stomper seemed to change into observation, and refusals ruled the day. I paused at 11:45PM to enjoy my lunch, and then afterward I replaced the hippie stomper with a size 14 olive deer hair caddis. The caddis produced a few fish to boost the fish count to seven, but it was very difficult to track in the glare and shadows, and it also elicited some refusals.

Next to the Exposed Boulder Was a Target

My mind went into overdrive, and I considered the idea of a beetle. Hatches are rare late in the season, but the 2025 autumn has been unusually mild thus enabling the survival of terrestrials. I knotted a size 14 Jake’s gulp beetle to my line, and I added a sunk ant on an eighteen inch dropper. Large black ants are quite prevalent in the South Boulder Creek canyon.

Very Nice Brown for a Small Stream

The move paid handsome dividends, and I built the fish count to eighteen, before I once again stalled. Five of the eaters during this span of time gobbled the sunk ant, but the rest sipped in the beetle. In addition I experienced many temporary hook ups, where the trout nipped the beetle, and I set and connected, but the fish wriggled free in a short amount of time. Beetle takes are very subtle probably because the small foam fly rides low in the water, and the fish dart to the surface and execute a quick sip.

Another Brown Trout Run

When I got stuck at eighteen, I began to notice an increased number of airborne insects over the water. The naturals included small caddis, a couple mayflies and a stonefly. This observation prompted me to swap the sunk ant for a size 16 gray deer hair caddis. The beetle and caddis combination raised the fish count from eighteen to twenty-four; its final resting place before I quit and completed the exit hike.

Large Tail

Twenty-four trout landed on a fall day in October is very satisfactory, but of course, many of the fish were small and in the six to nine inch length slot. However, I also landed a fat thirteen inch rainbow and two fourteen inch brown trout that challenge for the largest browns that I ever landed in South Boulder Creek. The second brown smacked the caddis near the end of the day.

As predicted, the weather was gorgeous. I had the stream completely to myself and the beetle was a solid attractor. I took advantage of one of the remaining nice days of 2025, and I am pleased with the results.

Fish Landed: 24