Meaning of low-water mark | Babel Free

Definitions

1. A mark, such as a line of seaweed, showing the lowest level reached by a body of water.
2. The nadir or lowest point of something.
   broadly

Examples

“Seven miles to the north of Venice, the banks of sand, which near the city rise little above low-water mark, attain by degrees a higher level, and knit themselves at last into fields of salt morass, raised here and there into shapeless mounds, and intercepted by narrow creeks of sea.”

CEFR level