Major Tributaries of the Colorado River: The Five Giants

Feeding the Artery of the Southwest

The Colorado's basin (637,000 km²) relies on these primary tributaries:

1. Green River (Largest)

• 730 mi; 40,000 mi² basin (WY, CO, UT)
• Joins in Canyonlands NP, UT
• Flaming Gorge Dam regulates flow

2. San Juan River

• 383 mi; 24,000 mi² (CO, NM, AZ, UT)
• Joins near Bluff, UT
• Navajo Dam reservoir

3. Little Colorado River

• 320 mi; 27,000 mi² (AZ, NM)
• Joins near Lees Ferry, AZ (Grand Canyon start)
• High sediment load; seasonal flow

4. Gila River

• 649 mi; 58,000 mi² (AZ, NM)
• Joins near Yuma, AZ
• Heavily diverted for agriculture; often dry lower reaches

5. Virgin River

• 264 mi; 12,000 mi² (UT, NV, AZ)
• Joins near Mesquite, NV (Lake Mead)
• Zion Canyon carved by its North Fork

System Stress

All overallocated. Climate change + demand = structural deficit. Tributary management now central to Colorado River survival.