Lake Powell’s inflow story is easier to understand in water-year form than in calendar-year slices. This page follows cumulative and daily inflow trajectories from October 1 forward so we can compare how each year built through snowmelt season and into late summer.
The first chart overlays all available water years. The second chart takes the selected calendar day and turns it into a year-by-year comparison so long-term context is easier to read.
How to use this chart
Use the legend controls to switch between actual and unregulated inflow, cumulative and daily mode, and which years are visible. The top chart answers “how did each water year progress?” while the lower chart answers “where does this date rank across years?”