San Juan Basin
![The San Juan structural basin is primarily in New Mexico and the southeast corner of the Colorado Plateau.](/Images/godic/202502/09/SanJuanBasinUSGS4941.jpg")
![The San Juan structural basin is generally the east portion of the San Juan River Watershed of 24,600 sq mi (64,000 km2) which extends farther west into Utah and Arizona.[1]](/Images/godic/202502/09/Sanjuanrivermap4941.jpg")
The San Juan Basin is a geologic structural basin in the Four Corners region of the Southwestern United States; its main portion covers around 4,600 square miles (12,000 km), encompassing much of northwestern New Mexico, southwest Colorado, and parts of Arizona and Utah.