Answer: cresting

AnswerCrossword Clue
CRESTINGReady to break, as a wave
CRESTINGTopping.
CRESTINGRising, as a flood
CRESTINGReaching the highest point
CRESTINGReaching a peak
crestingAn ornamental decoration at the ridge of a roof or top of a wall or screen
crestinga decorative coping