Boulder Creek & South Boulder Creek Fishing Guide

Quick Reference

What	When	Key Numbers
Boulder Creek	Aug-Sept best; year-round fishable	40-80 CFS ideal; catch-and-release; flies/lures only
South Boulder Creek	Aug-Sept prime; tailwater year-round	80-120 CFS ideal; 18"+ browns possible
Walker Ranch	Year-round (arrive early)	1.3-mile hike to tailwater; free parking
Eldorado Canyon	Year-round	State park fee required; massive boulders
Fly shops	Front Range Anglers	$395-495/day guided; free parking at Pearl St

Overview

Boulder Creek and South Boulder Creek offer two distinct fishing experiences within minutes of downtown Boulder. Boulder Creek flows right through the city, providing surprisingly good urban fishing with easy access. South Boulder Creek, fed by Gross Reservoir, is a lesser-known tailwater with trophy brown trout potential - some anglers regularly land 18+ inch fish here.

Both creeks hold healthy populations of brown and rainbow trout, with occasional cutthroat and brook trout mixed in. Boulder Creek is strictly catch-and-release with flies and lures only. South Boulder Creek at Eldorado Canyon allows a 4-fish limit but most anglers practice catch-and-release.

The trade-off: Boulder Creek is convenient but pressured. South Boulder Creek requires hiking but offers bigger fish and more solitude.

Boulder Creek

Character

Boulder Creek runs from the peaks of the Front Range through Boulder Canyon and into the heart of Boulder. The creek offers a unique mix of urban and mountain fishing - you can fish pocket water in the canyon in the morning and walk to a brewery afterward.

The canyon sections (Highway 119) provide classic pocket water with granite boulders, plunge pools, and riffles. The town section from Eben G. Fine Park to 30th Street offers slower glides, deeper pools, and good sight-fishing when water temps rise.

Fish species: Brown trout (most common), rainbow trout, cutbow hybrids, occasional cutthroat at headwaters, and brook trout.

Flow Windows

CFS	Conditions
15-40	Very low - technical fishing, requires stealth
40-80	Ideal for fishing - easy wading, fish feeding
80-150	Good fishing, some wading limitations
150-300	High water - tubing range begins, fishing tougher
300+	Dangerous - tubing bans typically enacted
1,200+	Moffat Tunnel releases - unfishable torrent

Note: Moffat Tunnel occasionally transfers water that can spike flows to 1,200 CFS with little warning, turning the upper creek into an unfishable torrent. Check flows before driving to the canyon.

Best fishing: Trout are most active when flows are changing - either starting to drop from peak or rise from the lowest levels. Very high and very low stable flows tend to produce the slowest fishing.

Access Points

Eben G. Fine Park (Town)

• West end of Arapahoe Ave, Boulder
• Easy access to town water with slower glides and pools
• Good sight fishing when temps rise
• Pocket water upstream of the playground often overlooked by midday crowds
• Tip: This is also the put-in for tubers, so summer afternoons get crowded

Boulder Canyon Pullouts (Highway 119)

• Multiple pullouts along the highway from Boulder to Nederland
• Mile markers 35-37: Best fishing stretch - terrific pocket water with pullouts on the left side of the road
• Past mile marker 37: Large pullout with parking area accesses nice pools and faster, tighter runs
• Mile marker 33.3: Just below Boulder Falls - scenic but crowded
• Lower canyon near Fourmile Creek confluence has best clarity
• Steep banks make access challenging in spots, but that means fewer anglers fish these sections
• Less pressure than town sections, especially early/late in day

Fourmile Canyon Confluence

• Where Fourmile Creek meets Boulder Creek
• Quieter stretch with deep buckets and soft inside bends
• Great for technical fall nymphing
• Mix of deeper runs and calm pools

Regulations

• Catch-and-release only from upper Eben G. Fine Park downstream to 55th St
• Flies and lures only - no bait
• All fish must be returned immediately
• Valid Colorado fishing license required (age 16+)

Hatches & Flies

Season	Primary Hatches	Recommended Flies
Winter	Midges	Black Zebra Midge (20-24), Mercury Midge, Griffith's Gnat
Spring	Little Black Stones, BWOs, Midges	Black Beauty (18-22), RS2, Juju Baetis (20-22)
Summer	Caddis, PMDs, Stoneflies, Terrestrials	Elk Hair Caddis (14-18), Stimulator (12-16), Hoppers (10-14)
Fall	BWOs, Midges	Parachute Adams (18-22), Purple Juju Baetis, Zebra Midge

Best approach: Dry-dropper rigs work well throughout the year, testing both surface and subsurface simultaneously. In the canyon, high-stick nymphing through pocket water is productive. In town, sight-fish to rising trout in the slower glides.

Water Temperature

Boulder Creek runs cold through the canyon but warms significantly as it flows through town and onto the plains. Upstream sections (canyon to South Boulder Creek confluence) are classified as Class 1 Cold Water and stay below 68°F (20°C) in summer. Downstream sections near 55th Street and beyond can reach 80°F+ during hot summer days.

Season	Canyon Temps	Town Temps
Winter	Upper 30s°F	Low 40s°F
Spring	Low-mid 40s°F	Mid 40s-50s°F
Summer	50-60°F	60-70°F (can exceed 70°F in afternoon)
Fall	Mid 40s°F	Low 50s°F

Summer fishing tip: When water temps push past 65°F (common in town sections during afternoon), trout stress and stop feeding aggressively. Fish early morning (before 11 AM) or late evening. The canyon sections stay cooler and fish better throughout the day.

Wading Conditions

The rocks in Boulder Creek are notoriously slippery - algae-covered cobbles will test your footing. Plant your feet before casting and test each step carefully.

• Felt soles with studs recommended - plain felt can be a slip-and-slide on the wrong algae
• Rubber soles with studs work well for the longer walks to canyon pullouts
• Wading staff helpful in faster water and for older anglers
• Winter: Watch for icy rocks, especially in shaded morning sections

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South Boulder Creek

Character

South Boulder Creek might be your best shot at a big wild brown in Boulder County. The tailwater below Gross Reservoir creates consistent cold flows that support large, healthy trout. Every year anglers land browns exceeding 18 inches, with the occasional fish pushing 20+.

The creek runs through some of the most beautiful mountain meadow and high-altitude pasture in the Front Range before dropping into Eldorado Canyon. Massive boulders create deep pools where big browns hide. The tailwater character makes this more technical than typical freestone fishing - expect midge-heavy conditions and selective trout.

Fish species: Brown trout (primary target, large specimens), rainbow trout, occasional brook trout and cutthroat. Rainbow and brook trout in Eldorado Canyon average 8-14 inches.

Flow Windows

CFS	Conditions
50-80	Low flows - very wadeable, technical fishing
80-120	Ideal range - good wading, active fish
120-200	Higher but fishable
200+	Difficult wading, especially in canyon

Best times: August and September are prime months - mild weather, abundant hatches, and perfect flows. The tailwater fishes well year-round, but summer and fall offer the best combination of conditions and insect activity.

Gross Reservoir note: Fall turnover at Gross can affect water temps and clarity. Check recent reports before making the drive.

Access Points

Walker Ranch Open Space (Tailwater Section)

The tailwater from Gross Reservoir to Eldorado Canyon is accessed via Walker Ranch.

• Trailhead: Walker Ranch Loop Trailhead, via Flagstaff Road from Boulder
• Hike: 1.3 miles down steep switchbacks through pine forest to the creek (allow 30-45 min down, longer coming back up)
• Trail: South Boulder Creek Trail drops to a bridge crossing, then flattens along the north bank with access to many fishing spots
• Parking: Free, but lot fills on weekends - arrive early. Meyers Gulch Trailhead usually has overflow parking. Restrooms available at trailhead.
• Cell coverage: Spotty to none - download maps and note your driving directions before losing service. Let someone know your plans.
• Tips: Bring snacks and water for the return climb. Informal routes lead upstream from the bridge to more secluded water.

Eldorado Canyon State Park

• Fee: Admission fee per carload (or per person if walking in). Colorado fishing license available at Visitor Center.
• Access: Designated fishing area stretches about 1 mile along the canyon bottom
• Character: Massive boulders, deep pools (up to 7 feet in places), stacked fish in summer/fall
• Regulations: No bait restrictions, 4-fish limit (catch-and-release encouraged)
• Warning: When flows are high, wading is not advised. The stream can be dangerously deep.

Hatches & Flies

South Boulder Creek is a dry fly paradise in summer, but requires technical midge and mayfly presentations in colder months.

Season	Primary Hatches	Recommended Flies
Spring	Midges, Black Stoneflies, BWOs	Zebra Midge (20-24), Black Beauty, Juju Baetis
Summer	Caddis, Green Drakes, Gray Drakes, PMDs, Yellow Sallies, Terrestrials	Superman Caddis, Purple Haze (16-18), Micro Chubby, PMD Sparkle Dun (16-18), Hoppers
Fall	BWOs, Midges	AR's BWO, Film Critic, Slick Midge, RS2 (20-24)

Subsurface patterns: Zebra Midge, Tag Perdigon, Rainbow Warrior, Juju Baetis, Walt's Worm, Sow Bug, Simple PTN, SOS Nymph

Tailwater tip: The drainage creates a midge factory. When fish aren't rising, small midge patterns in the film or just below are almost always productive.

Water Temperature

South Boulder Creek runs cold year-round thanks to releases from Gross Reservoir's deep, cold water. This is a major advantage in summer - when other Front Range streams are too warm to fish, South Boulder Creek stays in the mid-40s to low 50s°F.

Season	Typical Water Temp
Winter	Mid 30s-low 40s°F
Spring	Low-mid 40s°F
Summer	Mid 40s-low 50s°F
Fall	Mid 40s°F

Summer advantage: When Colorado is experiencing heat waves, this tailwater's consistent cold releases make it one of the best summer fishing options on the Front Range. Water rarely exceeds 55°F even in August.

Wading Conditions

The "massive eponymous boulders" that give South Boulder Creek its name create deep pools - some up to 7 feet. The rocks are slippery, and the water clarity is often crystal clear, requiring careful approaches.

• Felt soles with studs strongly recommended - especially for Eldorado Canyon's big boulders
• Approach from downstream to avoid spooking fish in clear water
• Wading can be tough when flows exceed 100 CFS - massive boulders create irregular depths
• Hip or chest waders recommended even in summer due to cold tailwater temps

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Seasonal Overview

Month	Boulder Creek	South Boulder Creek
Jan-Mar	Midges, cold but fishable	Tailwater midges, low pressure
Apr-May	Runoff begins, can blow out	Tailwater more stable than freestones
Jun-Jul	Post-runoff prime time, caddis	Caddis, drakes, dry fly season starts
Aug-Sep	Best months - terrestrials, stable flows	Best months - stacked fish, diverse hatches
Oct-Nov	BWOs, browns aggressive before spawn	BWOs, excellent fall fishing
Dec	Winter midges, low crowds	Tailwater stays open, technical

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Practical Tips

Gear Recommendations

• Rod: 9' 4-weight or 5-weight covers most situations
• Leaders: 9-12' tapered to 5X for dries, 6X-7X for technical midge work
• Waders: Breathable waders for Walker Ranch hike; wet wade in summer town sections
• Boots: Felt or rubber with studs for slick boulders

Before You Go

1. Check flows - Both creeks can change quickly. Boulder Creek spikes with Moffat releases; South Boulder varies with Gross Reservoir releases.
2. Arrive early - Walker Ranch and canyon pullouts fill by mid-morning on weekends
3. Bring layers - Canyon sections stay cool even in summer; Walker Ranch hike will warm you up

Local Resources

Two excellent fly shops in Boulder:

• Front Range Anglers (Pearl Street) - Since 1982, full guide service, lessons, and current conditions. Full-day guided trips: $395/1 angler, $495/2 anglers.
• Rocky Mountain Anglers - Free intro to fly fishing classes, gear, guides, and local intel.

Both shops monitor conditions closely and can tell you what's working right now.

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Water Recreation (Non-Fishing)

Boulder Creek through town is popular for tubing from May to September. The ideal tubing range is 100-200 CFS; flows over 300 CFS trigger bans due to safety concerns.

If you're fishing: Expect afternoon crowds near Eben G. Fine Park during tubing season. Fish early or head to the canyon for more solitude.

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Using RiverReports

Check current conditions before your trip:

• Boulder Creek flows - Real-time flow data
• Compare current CFS to the ideal fishing windows above
• Track whether flows are rising, falling, or stable

The creeks' proximity to town makes last-minute trips feasible - check flows in the morning and be on the water by afternoon if conditions look good.

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