San Juan-Colorado Basin Streamflow

Overview

The San Juan River is a major tributary of the Colorado River. This page tracks daily mean discharge at two basin-representative U.S. Geological Survey (USGS) gauges that collectively capture streamflow conditions across the San Juan basin in Colorado and New Mexico.

Current Status (as of July 7, 2026)

• San Juan River near Archuleta, CO: 1,050 cfs — upper basin
• San Juan River at Farmington, NM: 795 cfs — lower basin

The discharge decrease between Archuleta and Farmington (~245 cfs) reflects water diversions for irrigation and other uses in the intervening reach.

Data

Both series contain 364 daily observations, providing one year of continuous streamflow records. Typical summer baseflow (post-snowmelt) at this time of year ranges 400–1,200 cfs at Archuleta, depending on precipitation and snowpack conditions.

Use

Monitor these gauges for:

• Basin health: Dual-point tracking detects reach-specific trends
• Water availability: Summer streamflow guides irrigation allocation and environmental flow management
• Flood/drought signals: Rapid changes indicate upstream precipitation events or sustained dry periods