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 in April
Yosemite Falls in August
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.
- Sierra Nevada rivers (map)
- Average annual precipitation in the Sierra Nevada (map)
- Average maximum winter snow depth (map)
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