Charles H. Spurgeon on Psalms 78:44

And had turned their rivers into blood. The waters had been made the means of the destruction of Israel's newborn infants, and now they do as it were betray the crime —they blush for it, they avenge it on the murderers. The Nile was the vitality of Egypt, its true life blood, but at God's command it became a flowing curse; every drop of it was a horror, poison to drink, and terror to gaze on. How soon might the Almighty One do this with the Thames or the Seine. Sometimes he has allowed men, who were his rod, to make rivers crimson with gore, and this is a severe judgment; but the event now before us was more mysterious, more general, more complete, and must, therefore, have been a plague of the first magnitude. And their floods, that they could not drink. Lesser streams partook in the curse, reservoirs and canals felt the evil; God does nothing by halves. All Egypt boasted of the sweet waters of their river, but they were made to loathe it more than they had ever loved it. Our mercies may soon become our miseries if the Lord shall deal with us in wrath.