Definition of "high water"

high water

noun
countable and uncountable, plural high waters
1. (uncountable) The location of high tide on a coastal area.
  Quotations
  So as not to impede navigation the two principal spans of the bridge were designed to provide a clear headway of 157 ft. above high water for a distance of 500 ft.; [...].
  1941 January, the late John Phillimore, “The Forth Bridge 1890-1940”, in Railway Magazine, page 5
2. The state of the tide when the water is at its highest.
3. (countable) The highest stage of a river.