Hi & Welcome to Earthwaves,

Levels in water wells have been reported to increase or decrease before and after earthquakes, thus it is difficult to discern exactly what to expect with the variations.

The latest conjecture seems to be that water well level changes may be a result of ground tilt. If the ground is tilting then the water level may seem higher or lower, but in fact may not be.

The sulfur smell though is an entirely different matter and it certain gathers my interest. Have you noted any increase or decrease in local earthquakes, say within 16 kilometers of the wells location? If you need help with a catalog, I'm sure someone can run one for you.

Petra