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Calm stretch of the Green River below layered tan canyon wallsMarch 26, 2026
Length 730 miles
Class I–IV (by section)
Sections 17
Season May, Jun, Sep, Oct
Gateway Green River, WY
Colorado Plateau

Green River

The Green is the Colorado's longest tributary — 730 miles from Wyoming's Wind River Range through canyon gorges, wilderness flatwater, and the Confluence in Canyonlands. · WY · CO · UT

Overview

The Green River is the longest tributary of the Colorado River and the primary feeder of the Colorado Plateau’s canyon system — 730 miles from its headwaters in the Wind River Range of Wyoming to the Confluence in Canyonlands National Park. More than any other river in the American West, the Green defines what a desert river journey means: long days on wide, quiet water between walls of Navajo and Wingate sandstone, broken by canyon gorges that arrive without warning and demand full commitment. Canyon of Lodore, with its pool-drop whitewater and sheer Precambrian walls, is the fierce northern chapter. Desolation Canyon — 97 miles without a road crossing — is the longest wilderness river canyon in the Lower 48. Labyrinth and Stillwater are the quiet final miles, where the river slows to a canyon lake, and the water moves with the certainty of something that has always known where it was going. Partially regulated by Flaming Gorge Dam since 1964, the Green retains more free-flowing character than the Colorado, and its seasonal windows, permit logistics, and canyon character are the heart of Desert Maritime’s river intelligence.

Green River Sections

  1. Looking downstream at choppy whitecaps on a wide green flow, banks lined with bright spring cottonwoods below red cliffs

    A Section

    7 mi Class I–II · 1 day Seven miles of cold, clear tailwater through Red Canyon below Flaming Gorge Dam — extraordinary...
  2. Seen from above, a lone rower in a white wooden dory pulls through big green boils and breaking whitewater on the Green River at high flow.

    B Section

    9 mi Class I–II Nine miles of dam-regulated tailwater from Little Hole to Indian Crossing — the transition reach...
  3. A blue wooden dory, kayaks, and rafts drift down a calm green stretch of the Green River between steep red canyon walls

    Swallow Canyon

    10.8 mi Class I–II · 1 day Swallow Canyon is a cold, clear, and accessible float below Flaming Gorge Dam — regulated flows,...
  4. A person in a straw hat stands casting a fly rod from a wooden dory on the green Green River, a second person seated in the bow

    Browns Park

    18 mi Class I–II · 3 days A quiet, wildlife-rich valley float through outlaw country — Browns Park delivers 35 miles of easy...
  5. Silty water threads between large boulders in a deeply shaded stretch of Lodore Canyon, with a sunlit red peak rising beyond under a clear blue sky.

    Lodore Canyon

    18.7 mi Class III–IV · 4 days · Permit Required Lodore compresses everything that matters about western river running into seventeen miles. The...
  6. A pink gravel bar at Echo Park where the Green River bends beneath the striped wall of Steamboat Rock

    Echo Park

    2.5 mi Class I · Permit Required Two and a half miles from the Yampa confluence to the head of Whirlpool Canyon — the junction of the...
  7. Twin rock pinnacles stand silhouetted on a craggy, juniper-dotted canyon rim against a pale evening sky above Whirlpool Canyon.

    Whirlpool Canyon

    8.4 mi Class II–III · 2 days · Permit Required Whirlpool Canyon is the middle chapter of the Dinosaur river system — 8.4 miles of Class III...
  8. Overlook view of the Green River braiding around sandbars and yellow fall cottonwoods in the open Island Park valley at dusk

    Island Park

    4.6 mi Class I Four and a half miles of broad, island-dotted valley below Whirlpool Canyon — the open landscape...
  9. Golden cottonwood branches frame a calm green stretch of the Green River

    Rainbow Park

    1.7 mi Class I · 1 day · Permit Required Rainbow Park is a brief cottonwood bench between Island Park and Split Mountain — 1.7 miles of...
  10. Last sunset light glows orange on the tilted sandstone cliffs of Split Mountain above a calm stretch of the Green River

    Split Mountain

    8.3 mi Class III–IV · 1 day · Permit Required Split Mountain is the Green River's most concentrated whitewater — 9 miles punching through a...
  11. A dory under a tan canvas cover sits on its trailer on bare desert ground, pale eroded badland hills rising behind it in low warm light.

    Uinta Basin

    100 mi Class I About 100 miles of slow, open-country flatwater between Dinosaur National Monument and Sand Wash —...
  12. Rounded sandstone boulders on a cobble bank frame the silty brown Green River in Desolation Canyon, with a riffle breaking mid-river

    Desolation Canyon

    58.1 mi Class II–IV · 6 days · Permit Required Desolation is less about the rapids than about the accumulation of days inside something enormous....
  13. Two big cottonwoods frame Gunnison Butte across the fast, muddy Green River at Swaseys, with driftwood on the sandy beach

    Gray Canyon

    26.7 mi Class II–III · 2 days · Permit Required Gray Canyon is the whitewater-dense lower chapter of the Desolation-Gray run — 27 miles of Class...
  14. Satellite view of the low diversion weir angling across a bend of the silty Green River near the town of Green River, Utah

    Green River Valley

    10.7 mi Class I · 1 day Ten miles of flatwater through the broad valley of Green River, Utah — the connecting reach between...
  15. Pink sunset clouds above red sandstone cliffs and buttresses in Labyrinth Canyon, with riverside greenery in shadow below.

    Labyrinth Canyon

    68 mi Class I · 4 days · Permit Required Labyrinth is the Green River's argument that a canyon doesn't need rapids to be serious. Sixty-eight...
  16. Ice fringes the calm Green River between red sandstone canyon walls in Stillwater Canyon

    Stillwater Canyon

    54 mi Class I · 5 days · Permit Required Stillwater Canyon is the Green River's most remote flatwater journey — 52 miles of deep, quiet water...
Flows & Gauges

partially regulated — Flaming Gorge Dam (1964) controls the upper reach; below Jensen, UT the river flows without further major dams to the Confluence

Current flow — Green River near Greendale, UT

USGS
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Updating… Provisional

Green River at Jensen, UT

USGS #09261000

Current flow — Green River at Jensen, UT

USGS
—
Updating… Provisional

Current flow — Green River at Green River, UT

USGS
—
Updating… Provisional

The Green has distinct seasonal windows by section. Canyon of Lodore and Split Mountain are regulated by Flaming Gorge Dam and run May–June for peak flows; July–August is possible but hot and crowded. Desolation and Gray Canyons are best May–September with peak character in May–June runoff; the canoe-paddle sections (Labyrinth, Stillwater) are best April–October with peak weather in May and September–October. Summer heat in the lower canyon sections (Labyrinth/Stillwater) can exceed 105°F. Fall is superb throughout — lower flows, warm days, near-total solitude.

Geology

The Green River passes through some of the most geologically diverse terrain in North America. In Canyon of Lodore, it cuts through Precambrian Uinta Mountain quartzite — among the oldest exposed rocks on the Colorado Plateau. Through Desolation Canyon, it erodes soft Cretaceous and Tertiary sediments creating the largest roadless canyon in the contiguous United States. The river's course through the Uinta Mountains — an east-west trending Precambrian range unique in the Rockies — was established before the range's uplift began, allowing the river to cut downward through rising terrain in a classic antecedent drainage pattern.

Ecology

The Green River is critical habitat for all four federally listed endangered native Colorado River fish. The stretch from Flaming Gorge Dam to the Confluence is subject to active recovery programs coordinating releases, flow management, and habitat restoration. The cold, clear tailwater below Flaming Gorge Dam contrasts sharply with the warmer, silty flow that native fish evolved in — dam operations represent an ongoing tradeoff between the reservoir sport fishery and native species recovery downstream.

Biomes
Wyoming Basin sagebrush steppe (headwaters) Uinta Mountain subalpine (upper drainage) Colorado Plateau canyon desert riparian cottonwood-willow gallery
Notable species
Colorado pikeminnow (Ptychocheilus lucius) — endangered razorback sucker (Xyrauchen texanus) — endangered humpback chub (Gila cypha) — threatened bald eagle (Haliaeetus leucocephalus) — winter resident peregrine falcon (Falco peregrinus) great blue heron (Ardea herodias) river otter (Lontra canadensis) — historically present; localized recovery mule deer (Odocoileus hemionus) elk (Cervus canadensis) — upper reaches
Invasive species
tamarisk / saltcedar (Tamarix ramosissima) — established in lower canyon sections Russian olive (Elaeagnus angustifolia)
History
Indigenous homelands
Eastern Shoshone (Wyoming headwaters) Bannock Ute Nation — Uinta Band White River Ute
Explorers
John Wesley Powell William Ashley Jedediah Smith Jim Bridger

Notable Expeditions

  • Powell Green River Expedition 1869
  • Powell Second Expedition 1871
  • Ashley Fur Trade Expedition 1825