low-water mark 
noun
1The level reached by the sea at low tide, or by a lake or river during a drought or dry season: a shallow open pool at low-water mark...
- The vessel was sunk in the middle of the river below the low-water mark.
- We have to protect that strip of land that is from the high-water mark to the low-water mark.
- He said these were susceptible to a problem called ‘accelerated low-water corrosion’ which was corrosion around the low-water mark which could now be reinforced.
1.1A minimum recorded level or value: the market was approaching its low-water mark...
- On July 19, the Yankees reached a low-water mark when they fell 14 games back of the Red Sox.
- That last sentence must rank as one of the low-water marks of contemporary journalism.
- This model must be the low-water mark for their designers.
- well-liking
- well-limbed
- well-limned
- well-lined
- well-liquored
- well-lit
- well-liveried
- well-living
- well-loaded
- well-lodged
- well-looking
- well-lost
- well-loved
- well-lunged
- well made
- well maintained
- well-managed
- well-manned
- well mannered
- well marked
- well-married
- well-marshalled
- well-masked
- well matched
- well-mated