Did the water really turn to blood? Was this a miraculous event, or a natural phenomenon? People argue for both sides, and do so for just about every miracle in the Exodus. So it will help us to consider, can these things be “natural” events, or are they truly miracles from God?
On the one hand, God can work any miracle; even one like turning water to blood. Even if the water turning to actual blood would cause cataclysmic effects (as you imagine it would), God is able to reverse and heal those effects. If He can raise Jesus from the dead, He can turn water to blood.
But there may be some good reasons to think that maybe the text isn’t saying Moses and Aaron turned the water directly to blood. First, pharaoh doesn’t seem all that alarmed. You would think if all water turned to blood, that would have a hugely dramatic effect, and pharaoh would respond more desperately (as he will to later plagues). If those other plagues freak him out, why not water to blood? Second, there were times when the Nile’s water naturally turned red, when red clay got mixed into it, or plankton multiplied. That was a somewhat common occurrence. This could make the water undrinkable, and even affect the oxygen levels, thereby killing the fish. This kind of thing, I believe, is still referred to as “Red Nile” by modern Arab people. Third, there are examples of ancient manuscripts speaking of water turning to blood, and using that language metaphorically to speak of a terrible event; similar to how we use, “the streets ran red with blood.” There is precedent for the language being used symbolically. More interestingly, we have biblical examples of blood being used symbolically, and not “literally.” Joel 2:31 and Revelation 6:12 both talk of the moon turning to blood. When we say that, we understand the moon won’t actually change to blood. Furthermore, Jesus himself refers to blood metaphorically. He tells us, this is my body, this is my blood. We understand that Jesus doesn’t mean it’s His actual blood, and that He is speaking metaphorically.
So it could be that the water simply turned a deep red, and not actually to blood. But that doesn’t make this any less a miracle. It’s the timing of the miracle that makes the miracle We recognize elsewhere that the unusual control of naturals events can make for an impressive miracle. After all, some wind blowing around and then suddenly stopping doesn’t make for much of a miracle. We see that all the time, especially in Kansas! What we don’t usually see is a man who can control it, who can speak to the wind and say, “be still.” That is the work of God.
Is it a miracle, or a natural phenomenon? Both. God controls all nature, and all of its working is in His hands. Maybe we should be careful about separating the miraculous from the natural. The Lord is over all these things, and does with the natural what He will. And maybe we should begin to see the natural as a little more miraculous. We need not make a distinction. As we will see through the Exodus, He will exercise His will over creation, to show that He is truly Lord – YHWH – the I Am.