Note: This report is a part of the FlyCast Lite reporting program and is updated seasonally or in the event of substantial changes that alter fly fishing tactics. FlyCast Lite reports are intended to give anglers a high level overview on seasonal conditions and general fishing tactics.
While fishing at South Boulder Creek has been somewhat of a challenge as of late, given low flows, freezing temps and minimal bug life, you should see decent results with a little persistence. In general, flows below Gross Reservoir hold between 4 - 7 cfs for the better part of the winter, but you can expect some sporadic, yet substantial, and short-lived increases from time to time. In times of higher flow, you'll want to fish bigger searcher/attractor flies like a Pat's, Mini Leech, Pine Squirrel Leech, UV Scud or Worm. Small streamers are a good idea as well, especially on warmer days. Otherwise, small and imitative is the name of the game. Midges, like a Zebra Midge, Black Beauty, Top Secret, Mercury Midge, Medallion Midge, Pale Olive Midge and Pure Fire Midge are a good place to start. A dry dropper is a stealthy option as well. While you likely won't see much in the way of surface action, your presentation will likely be cleaner and you'll spook fewer fish. The mornings have been and will continue to be slow with sub-freezing overnight temps. However, the warmest hours of the day should produce the best results. Trout are stacking up in the deep and slow water most of the day and water clarity is generally high. As such, do your best to sight fish and adjust your weight accordingly so as to hit them on the nose with your flies.
South Boulder Creek is one of the more beautiful places to fish within an hour of Denver. It originates in the Indian Peaks Wilderness and makes its way down to the Gross Reservoir. Below the reservoir is the tailwater, which flows through the Walker Ranch Open Space. While the creek above the reservoir presents some decent fishing and offers a number of public access points, for the sake of this report, we’ll be focused on the section below the Gross Reservoir. The tailwater is home to a variety of trout species. However, it is most known for its brown and rainbow trout. This section is one of the more popular stretches and can be fished year-round. That being said, much of the river freezes over in the winter leaving fewer fishable locations. The creek itself meanders through a beautiful canyon and is detached from the road. So if you enjoy some peace and quiet as well as a short hike, South Boulder Creek is for you.
South Boulder Creek is fairly forgiving and a viable option for anglers of all skill sets. Given that it is a creek, you can expect comparatively narrow water as well as large boulders that create some amazing pocket water. While flows in the spring, late summer and fall are fairly stable, this stretch is particularly prone to run-off from feeder creeks. That said, you can still manage to catch fish during this time. The summer and fall offer prime dry fly fishing conditions as there are a variety of hatches in the caddis, PMD, BWO, midges and terrestrial variety. You can’t go wrong with the dry dropper set-up. Elk Hair Caddis, Amy’s Ant’s and Chubby Chernobyls all make for great point flies. Otherwise, the nymph rig with searchers, attractors or imitative nymphs will treat you well all year. Regardless of how you fish, you’re going to want to focus on the banks and outer seams to start, but don’t discount the shallow riffles and runs, pools or pocket water.
To access South Boulder Creek below Gross Reservoir, take Highway 93 (north from Golden or South from Boulder) until you reach Highway 72. From here, follow the highway until you reach the Gross Reservoir turnoff (Crescent Park Drive). After about 4.5 miles you’ll make a right on Gross Dam Road to which you’ll find parking via the Walker Ranch Open Space.