Explore the natural flow history at Lees Ferry, Arizona, with this interactive figure. Water supply has been variable over the last 1,200 years. The current drought is the driest 16-year period in the past 100 years and one of the driest 16-year periods in the past 1,200 years.

• Move the slider beneath the plot to select a window of time; you can go back as far as the year 762.
• Click and drag horizontally on the plot to zoom in on a particular time period, or vertically to zoom in on a flow range.
• Double click anywhere on the plot to zoom out again.
• Hover over a year in the plot to see that year's numbers appear in the legend.

Each line or ribbon of color represents a measure of natural flow. Tree-Ring Reconstructed Annual Natural Flow (light blue line) is the estimate of natural flow based on tree ring analysis; the very light blue shading behind the light blue line indicates the uncertainty in the reconstruction estimate. Historical Annual Natural Flow (dark blue line) is based on stream gage flow readings and is known with more certainty. Each point along the 10-Year Average Flow (red line) shows the average of the preceding 10 years, combining tree-ring reconstructed and historical values in years when both are available. The Long-Term Average Flow (yellow line) shows the average over the full 1,200+ years.