Then the third angel poured out his bowl on the rivers and the springs of water, and they turned into blood. 1
References for Revelation 16:4
16.4 Ex 7.17-21; Ps 78.44.
I heard the angel in charge of the waters say, "The judgments you have made are just, O Holy One, you who are and who were!
They poured out the blood of God's people and of the prophets, and so you have given them blood to drink. They are getting what they deserve!"
Then I heard a voice from the altar saying, "Lord God Almighty! True and just indeed are your judgments!"