Big Thompson River
Colorado · Front Range — Rocky Mountain National Park to Loveland
Brown TroutRainbow TroutGreenback CutthroatBrook Trout
Top Fishing Locations on the Big Thompson River
Moraine Park
The Big Thompson through Moraine Park meanders through an open, elk-filled meadow inside Rocky Mountain National Park , one of the most scenic trout fisheries in Colorado. Wild brown trout, rainbow trout, and brook trout populate the meadow sections, and if you're very fortunate you may encounter a native Greenback Cutthroat Trout, a federally threatened species making a slow recovery in the headwaters. A $25 RMNP day pass is required to fish here, and barbless hooks are mandatory throughout the park.
💧 Ideal flow: 30–120 CFS. The Moraine Park section is a small meadow stream that fishes best at lower, clearer flows. High runoff periods make wading difficult and fish spooky in off-color water.
📊 Get Location Flow Report
Tailwater
The 9-mile tailwater below Olympus Dam at Lake Estes is the most consistent and productive section of the Big Thompson. Cold releases from Lake Estes keep water temperatures ideal year-round, supporting excellent populations of wild brown and rainbow trout. This section is catch-and-release only with artificial flies and lures required , regulations that have produced quality fish averaging 12-16 inches. Access begins at the Mall Road pullout just below the dam, with numerous roadside pullouts along Highway 34.
💧 Ideal flow: 60–200 CFS. The tailwater fishes best at moderate flows when wading is comfortable and fish are in predictable lies. Above 300 CFS wading becomes difficult in the pocket water.
📊 Get Location Flow Report
Canyon Section
Below the Waltonia Bridge the Big Thompson transitions to classic Front Range freestone character , tight canyon pocket water flanked by granite walls and ponderosa pine, paralleling Highway 34 through Drake toward Loveland. This section offers nearly 10 miles of easily accessible public water with countless roadside pullouts. Wild browns and rainbows averaging 10-14 inches hold in the pocket water between riffles, with hatches of caddis, PMDs, stoneflies, and BWOs driving excellent surface action from late May through September.
💧 Ideal flow: 80–250 CFS. The canyon fishes best at moderate flows when the pocket water is fishable and fish are holding in predictable lies. Low summer flows concentrate fish in the deeper pools.
📊 Get Location Flow Report
Anson's Gear Picks
Rod — Budget · 9ft 4wt
Echo Carbon XL
Versatile trout rod
Rod — Premium · 9ft 4wt
G. Loomis IMX-Pro V2
Guide favorite
Reel — Budget
Hardy Marquis LWT
Trusted click pawl workhorse
Reel — Premium
Ross Animas
Colorado made guide reel
Waders — Budget
Simms Tributary Waders
Breathable entry level
Waders — Premium
Patagonia Swiftcurrent Traverse
3-layer GORE-TEX performance
Boots — Budget
Simms Tributary Boot
Rubber sole wading boot
Boots — Premium
Patagonia River Salt II
Premium rubber sole wading boot
Open Trout Bible →
About Big Thompson River Fishing
The Big Thompson River — known locally as the Big T — originates high in Rocky Mountain National Park's Forest Canyon and flows east through Estes Park, Lake Estes, and the dramatic Big Thompson Canyon to Loveland. It's one of Colorado's most accessible and productive Front Range fisheries, offering a rare combination of National Park meadow water, genuine tailwater character, and classic canyon pocket water all within easy reach of Denver and Fort Collins.
Best Time to Fish the Big Thompson River
The tailwater below Olympus Dam fishes year-round, making it one of the most reliable winter options on Colorado's Front Range when other rivers are locked in ice. Spring brings excellent midge and BWO hatches with light pressure. Summer peaks from late June through August with caddis, PMD, and stonefly hatches driving evening surface action, and dry-dropper rigs producing consistently through the canyon. Fall extends the dry fly season with BWO hatches and aggressive pre-spawn brown trout through October. The Moraine Park section inside Rocky Mountain National Park is best from June through September when the park is fully accessible and fish are active in the meadow.
Species
Wild brown trout dominate the canyon and tailwater sections, with rainbows mixed in throughout. Fish average 10-14 inches with larger fish possible in the deeper tailwater pools near the dam. Brook trout appear in the upper sections of Moraine Park. The native Greenback Cutthroat Trout — Colorado's state fish and a federally threatened species — inhabits the upper headwaters inside Rocky Mountain National Park and must be released immediately if encountered. Handling should be minimized and barbless hooks are required throughout the park.
Access and Regulations
The 9-mile stretch from Olympus Dam to Waltonia Bridge is catch-and-release only with artificial flies and lures required — one of the most significant special regulation sections on Colorado's Front Range. Access begins at the Mall Road pullout below the dam, with the Green Bridge pullout, Call Box pullout, and Big Lot pullout near mile marker 69 all providing easy roadside access along Highway 34. Below Waltonia Bridge, standard Colorado regulations apply through Drake and toward Loveland. Fishing inside Rocky Mountain National Park requires a $25 day pass (or annual pass) and barbless hooks throughout. Private property on the non-highway side of the river is well-marked — respect posted boundaries. A Colorado fishing license is required for all anglers 16 and older.
Live River Data
Flow data for the Moraine Park section is pulled from USGS gauge 402114105350101 (Big Thompson below Moraine Park near Estes Park). The tailwater and canyon sections use Colorado DWR gauge BTBLESCO (Big Thompson River Below Lake Estes). The tailwater's flow is controlled by releases from Lake Estes/Olympus Dam and can change throughout the day — checking gauge data before heading out is particularly important for this section.