Genesis 8:3

And the waters returned from off the earth continually: and after the end of the hundred and fifty days the waters were abated.

Cross-reference

Genesis 7:11 records the opening of the fountains and windows — the start of the flood, while here they close and waters recede.

Genesis 7:24 notes the waters prevailed 150 days — here they begin to recede after that same period, continuing the narrative.