Noun
the tide when the water is highest
Source: WordNetAs with the highwater records, monthly low water records were set each month from February 1964 through January 1965. Source: Internet
All park facilities above the highwater mark remain closed to the public, including the 100-feet-long cement pier on the south side. Source: Internet
Instead of periodic highwater crests only steady flows came down the river. Source: Internet
The book concluded that "Zork III represents a highwater mark for subtlety and logic, and is a Four Star must". Source: Internet