The San Juan River is a tail water fed by Navajo Reservoir (Dam). Flows are regulated by the Bureau of Reclamation; with normal levels at or around 500cfs. Depending on snowpack received  in the La Plata  mountains during the winter, the BOR will increase the flow of the San Juan in the late spring/early summer for a period of about 3 weeks at 5,000cfs to imitate historical spring runoffs (pre-dam).

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During this spring runoff, wading is discouraged, limiting anglers to use a drift boat to fish the San Juan

 

The chart on the left shows the most recent flow data in cubic feet per second. For BOR specs visit the USGS Website.