Troutline

Blue River

Colorado·Western Slope·39.65° N, 106.07° W
Flow
38.8 CFS
Blue R at Blue River
Water Temp
45°F
Blue R near Dillon
Condition
Below Normal
Weather
43°F
Chance Rain And Snow Showers

Insights

Water Temp
Water 45°F — prime
Active-feeding window.
Pressure
Pressure dropping
Fish often move up to feed before a front.
Lunar
New moon tonight
Dark nights — fish are more likely to feed through the day.
Flow
Low flows at 38.8 CFS
Fish are spooky. Lighten tippet and lengthen leaders.
Snowpack
Snowpack 13% of normal
Blue River basin snowpack is at 13% of normal — expect an early runoff and low summer flows, with tailwaters and spring creeks holding up best. The May–July runoff forecast for Green Mountain Reservoir Inflow is 24% of average.

The Blue River runs about 65 miles from Hoosier Pass through Breckenridge and Dillon Reservoir, then below Dillon through Silverthorne, on through Green Mountain Reservoir, and out to its confluence with the Colorado River at Kremmling. Three distinct fly-fishing fisheries: the upper river above Dillon Reservoir through Breckenridge (small, technical, and not particularly highly regarded), the Silverthorne tailwater below Dillon Dam (an unusual urban C&R tailwater running through the Outlets Mall), and the lower Blue below Green Mountain Reservoir (the river's most respected stretch and a Gold Medal fishery from the dam to the Colorado confluence).

The Silverthorne tailwater fishes year-round on stable cold releases from Dillon. The 'Outlets Mall' stretch is the most-photographed urban fly-fishing water in Colorado — concrete walls, parking-lot access, and big selective rainbows feeding on Mysis shrimp flushed from Dillon Reservoir. Mysis dominates the diet immediately below the dam; tiny midges and BWOs fill in the rest of the year. The technical fishing rivals Cheesman Canyon for difficulty — selective fish, heavy pressure, and constant Mysis competition. Below the C&R section the river continues as a public-fishing stretch for about 6 miles to Green Mountain Reservoir.

Below Green Mountain Reservoir the Blue becomes a different fishery — bigger, freestone-like flows, wild brown trout, and 14 miles of Gold Medal water down to the Colorado at Kremmling. The lower Blue fishes hopper-dropper through August-September and produces the river's biggest fish in fall on streamers. Wade access is BLM-managed below Green Mountain Dam; drift boats are common on the lower reaches. The lower Blue has a seasonal closure from September 15 through December 1 to protect spawning brown trout. Drive times: 90 min from Denver to Silverthorne, 2 hr from Denver to Green Mountain Reservoir. Elevation 7,500 ft (Kremmling) to 9,000 ft (Silverthorne). Hwy 9 follows the entire river.

Species

SpeciesAbundanceBest SeasonSizeNotes
Rainbow TroutCommonYear-round14-22"Wild and stocked. Trophy rainbows in the Silverthorne tailwater feed on Mysis shrimp — fish to 24 inches are caught regularly. Wild populations also strong below Green Mountain Reservoir.
Brown TroutAbundantSep-Nov12-22"Dominant species on the lower Blue below Green Mountain Reservoir. Wild population with strong fall spawn — note the Sep 15-Dec 1 lower river closure to protect spawning fish.
Mountain WhitefishCommonYear-round10-16"Native and abundant on the lower Blue. Aggressive nymph eats year-round.
Cutthroat TroutLimitedJul-Sep8-14"Native populations in upper headwater tributaries above Dillon. Not a target on the mainstem.
Ideal wading flow100500 CFS
Blow-out>1,000 CFS
Ideal water temp4460°F

Silverthorne tailwater: year-round, best in winter and early spring. Lower Blue (Green Mountain to Colorado): July through September 14 (then closed Sep 15-Dec 1 for brown spawn), reopens December 2. Streamer game on the lower river is December-March only due to the spawn closure.

Sections

5 sections on this river

Lower Blue — Spring Creek to Colorado River (Kremmling)

FloatBrown Trout · Rainbow Trout

Final reach down to the confluence with the Colorado River at Kremmling. Bigger water, longer pools, the river's trophy fish concentrated in this stretch. Drift boats are the practical means of covering water. BLM access at Sheephorn.

Best for: Trophy wild brown trout on streamers, hopper-droppers, and stonefly nymph rigs. Best Jul-Sep 14; closed Sep 15-Dec 1.

Lower Blue — Green Mountain Dam to Spring Creek

Wade & FloatBrown Trout · Rainbow Trout

Below Green Mountain Reservoir the Blue becomes a serious freestone-style fishery. BLM access at Spring Creek and Trough Road. Big wild brown trout in deeper pools and runs. Note the Sep 15-Dec 1 closure to protect spawning browns.

Best for: Wild brown trout and rainbow trout on hopper-droppers, caddis, and streamers. Best Jul-Sep 14; reopens Dec 2.

Silverthorne to Green Mountain Reservoir

WadeBrown Trout · Rainbow Trout

Six-mile transitional reach below the C&R section to the inflow of Green Mountain Reservoir. Public-fishing easements along Hwy 9. Less pressured than the Outlets stretch; mix of wild and stocked trout.

Best for: Rainbow trout and brown trout on standard nymph rigs, BWOs, and midges. Best Apr-Oct.

Silverthorne Tailwater — Dillon Dam to Hwy 9 Bridge

WadeRainbow Trout

Two-mile catch-and-release tailwater below Dillon Dam — flows directly through the Silverthorne Outlets Mall complex with concrete bank stabilization and parking-lot access. Mysis shrimp from Dillon Reservoir produce trophy rainbow trout that feed selectively on tiny imitations.

Best for: Trophy rainbow trout on Mysis patterns, midges, and BWO emergers. 6X-7X tippet, long leaders, careful presentations. Best year-round, especially winter weekday mornings.

Upper Blue — Breckenridge to Dillon Reservoir

WadeBrown Trout · Rainbow Trout

Small headwater stream through Breckenridge to the inflow of Dillon Reservoir. Heavily impacted by historic mining and recreation pressure. Not a destination fishery; small browns and rainbows in the slower pools.

Best for: Small wild brown trout and rainbow trout on attractor dries and dry-dropper rigs. Best Jul-Sep.

Regulations

Current fishing rules and restrictions

Two distinct regulation zones. Silverthorne tailwater: catch-and-release artificial-only on the upper stretch. Lower Blue below Green Mountain Reservoir: Gold Medal water with C&R and seasonal closure to protect spawning brown trout (closed Sep 15-Dec 1, 2026 update).

  • Silverthorne tailwater (Dillon Dam to Hwy 9 bridge, about 2 mi): artificial flies and lures only, catch-and-release
  • Lower Blue (Green Mountain Dam to Colorado River, 14 mi Gold Medal): artificial flies and lures only, catch-and-release
  • Lower Blue Sep 15-Dec 1 seasonal closure (2026 update): no fishing during fall brown trout spawn
  • Upper Blue above Dillon Reservoir: standard statewide limits (4 trout daily / 8 in possession) where not specially regulated

The 2026 seasonal closure on the lower Blue (Sep 15-Dec 1) is new — protects fall spawning brown trout. Plan trips around the closure window. The Outlets Mall section in Silverthorne is one of Colorado's most heavily pressured pieces of water year-round; weekday mornings produce the best fishing. The lower Blue below Green Mountain Reservoir is closed for several hundred yards immediately below the dam — check posted signs.

Source: Colorado Parks & Wildlife — Fishing Regulations. Regulations change annually — verify before fishing.

Access & Logistics

Getting there, fly shops, and lodging

Getting There

Silverthorne, CO (upper tailwater); Kremmling, CO (lower river / Green Mountain area)

90 min from Denver to Silverthorne; 2 hr from Denver to Green Mountain Reservoir; 30 min Silverthorne to Green Mountain Reservoir

Fly Shops

Camping & Lodging

Heaton Bay, Lowry, and Pine Cove campgrounds at Dillon Reservoir. Cataract Lake Campground and BLM camps along the lower Blue. Hotels and condos in Silverthorne, Frisco, and Dillon. Cabins at Heeney near Green Mountain Reservoir.

Silverthorne tailwater access: park at the Outlets Mall lots and walk to the river. The river flows through the mall complex with concrete bank stabilization in places. Lower Blue below Green Mountain: BLM access points at Spring Creek, Trough Road, and Sheephorn. Hwy 9 parallels the entire river. Drift boats become practical below Green Mountain Reservoir.

Conditions data is live from public monitoring networks. Regulations change annually — always verify current rules with your state fish & wildlife agency before fishing.

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