Sierra Nevada River Flows

Sierra rivers vary widely in average monthly flow due to the seasonal nature of precipitation in California. Though precipitation peaks in January though March, river flows peak in April and May when significant snow melt occurs. August through October are typically the months of lowest river flow, and flows in these months average only three to ten percent of the Spring maximum.

The photos below show Yosemite Falls in April, near maximum flow, and August, when the flow has dropped to a trickle. In dry years, Yosemite Falls may run completely dry by September.

Yosemite Falls - April
Yosemite Falls in April
Yosemite Falls _August
Yosemite Falls in August

The Feather River is by far the largest river in the Sierra in terms of flow, due both to its large basin and the high levels of precipitation that the northernmost Sierra receives.

The chart below shows the monthly average estimated full natural flow (FNF, the flow of the river if not impaired by dams and diversions) for twelve major Sierra Nevada rivers.

See also:

Sources:
Central Valley Project Improvement Act Tributary Production Enhancement Report, US Fish and Wildlife Service, May 1998.
Raw data obtained from:
California Department of Water Resources, California Data Exchange Center
Water Resources Data California Water Year 2000, Volumes 3 and 4, US Dept. of Interior, US Geological Survey