Fly Fishing Blue River - Below Green Mountain

Fly fishing Blue River below Green Mountain Reservoir delivers a secluded, year-round tailwater adventure in a narrow canyon of central Colorado. Fed by deep-cold releases from Green Mountain Dam, the Blue River maintains cool, crystal-clear flows even when nearby freestone streams run low or freeze. Towering sandstone and quartzite walls rise on both sides, punctuated by stands of scrub oak and Gambel oak, while the riverbed cascades through deep pools, pocket water, and shallow riffles that hold wild rainbow trout and brown trout from winter through summer. For anglers seeking solitude and sight-fishing opportunities, the Blue River below Green Mountain Reservoir is nothing short of spectacular.

Access to this backcountry gem requires a strenuous hike down steep switchbacks and loose talus slopes—especially challenging in winter when ice and snow make the trail slippery and narrow. From the trailhead near the dam, anglers descend several hundred vertical feet over uneven footing before reaching the river; winter hikers should prepare for icy sections, wear crampons or traction devices, and carry trekking poles. Once on the riverbank, the reward is immediate: glass-green water teeming with wary trout that have seen few flies. High summer flows (June–July) can surge after snowmelt, turning shallow runs into swift currents, while late summer releases often drop to wading levels (100–200 CFS), prompting anglers to downsize to sub‐18 nymphs and punt roller patterns to tempt pressured fish.

Spring (April–May) brings prolific stonefly and caddis hatches in the riffles near mid-canyon narrows, drawing trout into mid-river seams. Nymph anglers thrive during these months by probing deep slack water and undercut banks with balanced rigs and tungsten‐headed flies. Dry-dropper setups can also be effective when surface‐skimming caddis emerge in late May. In summer (August–September), tiny mayflies and midges hatch in the early hours, rewarding those who arrive before dawn with rising trout in shallow runs. Hopper and terrestrial action is minimal here; instead, focus on tight-line nymphing under clear currents or swinging soft hackles through the seams of deep pockets.

Fall (October–November) sees flows stabilize under golden scrub oaks and cottonwood groves that line the upper banks, with sporadic midge and late-season mayfly activity igniting delicate dry-fly opportunities. As winter chills set in, flows remain steady but fishing strategy pivots to micro-nymphs and ice-edge tactics; targets move into seams beneath undercut ledges where water temperatures stay just above freezing.

Check our live Blue River flow gauge and hatch chart before you head out to dial in both flow levels and insect activity. Whether you’re probing deep tailwater seams with technical nymph rigs in spring or chasing the few rising fish under autumn’s midge clouds, the Blue River below Green Mountain Reservoir rewards the well-prepared angler with solitude, healthy wild trout, and rugged canyon scenery that few Colorado fisheries can match.