clear and still water
澂 centers on water that is clear, still, and transparent, free from disturbance or impurity.
澂 is the older traditional form of 澄. It combines 氵 (water) with 徵, which likely contributed the sound and the idea of clarity or purity. The modern simplified form 澄 replaces the right side with 登.
The water radical 氵 on the left flows into a right side that looks like a mountain 山 with a ruler 王 and an action hand 攵, as if the water has been measured and settled until it becomes perfectly clear and still.
For チョウ, picture a long-serving water guardian named Chou who keeps the pond perfectly clear and still: Chou -> チョウ, and the water is always transparent.