Floating the Upper Colorado in Summer

Quick Reference

What	When	Key Numbers
Pumphouse to State Bridge	July-Sept	14 mi; 4-6 hrs; Class I-II; Gold Medal water
Ideal floating flows	July-Aug typical	1,500-3,300 CFS; below 1,000 better for fishing
Gold Medal fishing	Year-round (July-Sept prime)	4,000-5,000 trout/mile; 16-17" common
Camping	Reserve via Recreation.gov	Pumphouse $25/night + $10 day use (eff. July 2025)
Shuttle	Rancho del Rio	$50-105; vehicles ready by 1pm
Guided fishing	Book ahead for July-Aug	$500-650/day; Mountain Angler

Overview

The Upper Colorado River from Pumphouse to Dotsero is one of Colorado's best summer float trips. This 60+ mile stretch offers Class I-II water through scenic BLM canyon lands - ideal for family floats, multi-day camping trips, or serious fly fishing.

What sets this section apart: it holds Gold Medal water designation. CPW electrofishing surveys find 4,000-5,000 trout per mile in the Pumphouse to Catamount section, with 16-17 inch fish common. The largest brown ever documented here was 17 pounds.

Summer (July-September) is prime time. Runoff has subsided, flows settle into ideal ranges, and the canyon sees less crowding than Colorado's more famous rivers. The catch: no cell service from Pumphouse through the canyon, so plan accordingly.

Flow Windows

Understanding flows is essential for timing your trip. Check Colorado River flows near Kremmling before launching.

Flow (CFS)	Conditions
Under 600	Low water - scraping likely, slower float, some portaging possible
600-1,000	Prime fishing flows - Class II rapids become gentler Class I-II, excellent wade access
1,000-1,500	Low-normal floating - relaxed pace, some shallow spots
1,500-3,300	Ideal floating range - good current, Class II rapids run clean
3,300-5,500	Higher water - faster, more technical, experienced paddlers only
Over 5,500	High water - bridge clearance issues at second bridge, significant hazards

The ideal floating window of 1,500-3,300 CFS typically occurs from late June through mid-August. By late August and September, flows often drop below 1,000 CFS - still floatable but slower, with better fishing conditions.

Key Sections

Pumphouse to Radium (4 miles)

The most popular short float, taking 2-2.5 hours at typical summer flows.

Rapids:

• Wake Up Rapid (Class II) - straightforward warm-up at river mile 1
• Needle's Eye (Class II) - the signature rapid with a narrow chute through a rock garden. Scout from river-left if unfamiliar.
• Mary's Wall - immediately after Needle's Eye, the river pushes right into a cliff. Stay left at all water levels.

Takeout bonus: Radium Hot Springs and Jump Rock are at the takeout - natural warm springs tucked against a popular cliff jumping spot.

Radium to Rancho del Rio (6 miles)

Longer section through the canyon with consistent riffles and a more remote feel. Takes 3-4 hours.

Rapids:

• Red Eye Rapid (Class II-III at higher flows) - most significant feature in this section
• Yarmony (Hoyt) Rapid (Class II, up to III at 2,500+ CFS) - the most consequential rapid on the upper stretch. At higher flows, a large boulder creates a hole that can flip rafts. Stay center-right to avoid the hole.

Nine on-river primitive campsites are available first-come, first-served through this section.

Rancho del Rio to State Bridge (4 miles)

The mellower finish to a Pumphouse-State Bridge day float. Mostly Class I-II water. Takes 1.5-2 hours.

Total Pumphouse to State Bridge: 14 miles, 4-6 hours depending on flow and fishing stops.

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State Bridge to Dotsero (45 miles)

The lower stretch sees far less traffic and is typically done as a multi-day trip. Character changes to wider, mellower water through ranch country.

Section	Distance	Float Time	Notes
State Bridge to Catamount	16 miles	6-7 hours	Class I-II, mellow, great camping
Catamount to Pinball	9 miles	4-5 hours	Remote, Bull Gulch WSA
Pinball to Dotsero	20 miles	8-10 hours	Long day or split into two

Rapids Below State Bridge:

• Windy Point (Class II) - only named rapid in the upper portion
• Alkali (Class II) - below Catamount
• Landslide/Rodeo Rapid (Class III) - solid drop, easy to scout from road if needed
• Pinball Rapid (Class III) - fun wave train
• Twin Bridges (Class II+) - marks end of the scenic canyon stretch

Why do the lower stretch? Solitude. You'll likely have the river to yourself, and the camping at Jacks Flat is considered by many the best on the entire Upper C - a quiet site with a natural berm blocking road and railroad noise.

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Access Points & Logistics

All access points are managed by BLM Kremmling Field Office. Note: New fee structure takes effect July 7, 2025.

Pumphouse Recreation Site (Primary Put-in)

• Three boat ramps (Launch 3 is ADA accessible)
• 18 individual campsites - $25/night (reservations required via Recreation.gov)
• 2 group campsites - $75/night
• Vault toilets, drinking water (summer only - not always operational)
• Day-use parking: $10 per vehicle (vehicle season pass: $50)
• Camp host on-site during summer
• No cell service - Kremmling (15 miles) is nearest town for supplies

Radium Recreation Site

• Mid-river access with two launch areas
• 9 standard campsites - fees similar to Pumphouse
• Good swimming at Radium Hot Springs adjacent to takeout

Rancho del Rio

• Private lodge/campground with river access
• Restaurant, general store, cabins
• Shuttle service available (see below)

State Bridge

• Concert venue and lodge with restaurant, cabins, general store
• Day-use: $10 per vehicle
• Paved boat ramp
• 14 miles from I-70 (Wolcott Exit #157)

Lower Section Access (State Bridge to Dotsero)

Six BLM-maintained access points allow trip customization:

• Catamount - vault toilet, fire rings, picnic tables
• Pinball Point - similar facilities
• Windy Point - camping with toilet and fire rings
• Cottonwood & Lyons Gulch - developed campsites
• Jacks Flat - wilderness-style camping (bring your own toilet system)
• Dotsero - final takeout before Glenwood Canyon

Getting There

From Denver (2 hours): I-70 west to Exit 205 (Silverthorne), Highway 9 north through Kremmling, then Trough Road (County Road 1) west for 10 miles to Pumphouse.

From Vail (45 minutes): I-70 to Exit 157 (Wolcott), Highway 131 north for 12 miles to State Bridge.

Road conditions: Trough Road is maintained gravel, passable for most vehicles in dry conditions. Can get rough after rain - high clearance helpful but not required.

Shuttle Services

Most floaters run a two-vehicle shuttle. If you only have one vehicle:

Rancho del Rio - (970) 653-4431

• Shuttles from Pumphouse to State Bridge and other combinations
• $50-105 depending on route
• Vehicles must be at put-in by 1:00pm for same-day service
• Book online at ranchodelrio.com

AVA Rafting - coloradorafting.net

• Shuttle service from Kremmling outpost
• Add to raft rental bookings

Tip: Day-use fees apply at both put-in and take-out, including shuttled vehicles.

BLM Contact: Kremmling Field Office - (970) 724-3027

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Summer Fly Fishing

The Upper Colorado fishes well all summer, with different patterns emerging as conditions change.

July: Post-Runoff Prime Time

Water clarity improves dramatically once runoff subsides. Golden Stoneflies follow the salmonfly hatch, with peak activity in the first two weeks of July. This is arguably the best month for dry fly fishing.

Key Hatches:

• Golden Stoneflies (#8-12) - fish dries and nymphs
• Yellow Sallies (#14-16) - Mercers Micro Stone
• Caddis (#14-18) - evening hatches produce rising fish
• PMDs (#16-18) - late morning to early afternoon

August: Hopper Season

As flows drop below 1,000 CFS, the river reveals rock gardens and sandy bars perfect for hopper-dropper rigs. Fish move into shallower water along willow-lined banks.

Key Hatches:

• Terrestrials (hoppers, beetles, ants) - work the banks
• Yellow Sallies continue
• Caddis (#16-18) - consistent evening activity
• Tricos (#20-24) - early morning spinners

September: Fall Transition

Cooler nights trigger renewed mayfly activity. Brown trout become more aggressive as spawn approaches.

Key Hatches:

• BWOs (#18-22) - afternoon hatches on cloudy days
• Streamers become increasingly effective
• Midges (#20-24) - consistent subsurface food source

Fly Box Essentials

Dries:

• Elk Hair Caddis (#14-18, tan and olive)
• Yellow Stimulator (#14-16)
• Schroeder's Parachute Hopper (#8-12)
• Parachute Adams (#16-20)
• Chubby Chernobyl (#10-14)

Nymphs:

• Pat's Rubberlegs (#6-10, black/brown)
• Pheasant Tail (#16-18)
• Hare's Ear (#14-16)
• RS2 (#18-22)
• Zebra Midge (#18-22)

Streamers:

• Woolly Bugger (#6-10, olive and black)
• Slumpbuster (#4-6)
• Sculpzilla (#4-6)

Wade vs. Float Fishing

Float fishing covers more water and accesses private stretches between public access points. Best when flows are 800-2,000 CFS.

Wade fishing becomes excellent as flows drop below 1,000 CFS in late summer. Rock gardens and gravel bars emerge, allowing access to runs that were unreachable earlier. Best access points for wading:

• Below Pumphouse boat ramp
• Radium area
• BLM pullouts along Trough Road between State Bridge and Catamount

Best Times of Day

• Early morning (6-9am): Cooler water, active fish, Trico spinners in August
• Late morning (10am-noon): PMD activity, comfortable air temps
• Evening (6-8pm): Caddis hatches, rising fish, best dry fly window

Water Temperature Warning: Stop fishing when water temps reach 68°F. Trout become stressed above 65°F and mortality risk increases even with careful handling. Carry a stream thermometer - afternoon temps can spike during July heat waves.

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Hazards

High Water (Flows above 3,300 CFS)

• At flows over 5,500 CFS, you cannot float under the second bridge
• Yarmony Rapid becomes a serious Class III with a boat-flipping hole
• Cold water persists even when air temps are warm
• Faster current means less reaction time for obstacles

Strainers (Downed Trees)

Strainers accumulate on outside bends after high water events. Scout any unfamiliar sections. If swimming and you can't avoid a strainer, turn onto your stomach and climb up and over - never swim underneath.

Weather

Afternoon thunderstorms are common July-August. Plan to be off the water by early afternoon if storms are forecast. Lightning is the primary danger.

No Cell Service

There's no cell coverage from Pumphouse through the canyon to State Bridge. Plan accordingly:

• Tell someone your float plan and expected return
• Bring a satellite communicator (Garmin InReach) for emergencies
• Know basic self-rescue techniques

Overnight Trip Requirements

For on-river camping, BLM requires:

• Fire pan for any campfires
• Leak-proof human waste containment system (WAG bags)
• Pack out all trash

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Gear Recommendations

Floating Essentials

• Coast Guard-approved PFD for each person
• Dry bag for valuables and dry clothes
• Water and snacks (plan for full-day hydration)
• Sun protection - hat, sunscreen, polarized sunglasses
• River sandals or water shoes
• Throw rope (50+ feet)

Fishing Gear

• 9' 5-weight rod (good all-around choice)
• 9' 4-weight for dry fly work in late summer
• Floating line with 9' 4X-5X leader
• Stream thermometer
• Waders for early morning/cool days (late summer you can wet wade)

Multi-Day Additions

• Fire pan
• WAG bags or portable toilet system
• Water filter
• Tent, sleeping gear
• Cooler for food (dry ice lasts longer than regular ice)
• Camp chair
• Headlamp
• Bug spray (mosquitoes can be heavy at Jacks Flat)

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Seasonal Summary

Month	Typical Flows	Conditions	Best For
Late June	2,000-3,500 CFS	Dropping from runoff	Experienced floaters, late salmonflies
July	1,200-2,500 CFS	Prime floating	Everyone - best balance of current and safety
August	600-1,200 CFS	Lower, slower	Fishing, families, multi-day trips
September	400-800 CFS	Low water	Wade fishing, fall colors, solitude

The Upper Colorado has a longer season than many Colorado rivers, often remaining floatable into late September when other rivers have dropped too low.

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Guided Options

Rafting Outfitters

AVA Rafting - coloradorafting.net

• Operates from Kremmling outpost
• Half-day scenic floats, ages 2+
• Raft rentals from $199

Colorado River Rentals - coloradoriverrentals.com

• Self-guided raft rentals with shuttle service

Rancho del Rio - ranchodelrio.com

• Shuttle service and trip support

Fly Fishing Guides

Mountain Angler (Breckenridge) - mountainangler.com

• Permitted on 50+ miles from Pumphouse to Dotsero
• Exclusive access at Yellow Dog Ranch

Kirks Flyshop (Grand Lake) - kirksflyshopgrandlake.com

• Half-day ($500) and full-day ($650) float trips
• All gear provided including lunch on full days

Vail Valley Anglers - vailvalleyanglers.com

• Detailed fishing reports on current conditions

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Using RiverReports

Plan your trip with real-time data:

• Colorado River near Kremmling - primary gauge for this stretch
• Compare current flows to seasonal averages
• Set flow alerts to know when conditions hit your target window
• Check the 7-day forecast to time your trip

The Upper Colorado's natural flow pattern means conditions can change more quickly than dam-controlled rivers. Check flows within 24-48 hours of your trip, not just a week out.

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For June floating during runoff season, see our Upper Colorado June Guide. For statewide conditions, visit Colorado rivers.