A reservoir gauge chart plots elevation over time against reference lines for full pool and conservation pool. The shape — not a single point — tells the story.
A steep recent drop signals drawdown or drought; a flat line near full pool means normal operations. Year-over-year overlays show whether this season is unusual.
Pair the current reading with the historical median for the date to judge whether a lake is genuinely low or simply following its seasonal curve.
Try it: live lake levels.