Greta Hort in the 1950’s attempted to explain the 10 plagues on Egypt naturalistically (without God). She proposed that a type of red algae (along with silt) washed into the Nile releasing toxic bacteria. This caused frogs to evacuate the river and die on the banks. Flies and gnats fed on the corpses and created a pestilence which killed cattle and caused people to break out in boils. This coincided with natural events such as hail, thunder, and a desert sandstorm which drove locusts into Egypt. There are many problems with this analysis. River silt should be brown, not red. Red algae does not exist in the Nile and is non-toxic. It was the wrong time of year for hailstorms/sandstorms. Also, streams, pools, and ponds became blood—even buckets and pitchers (Ex. 7:19)! Exod. 7:21, 24 indicate only Egyptians could not drink it, Jews seemingly could. The ancient historian Josephus verifies this. Atheists only accept the Biblical record so far as they can “refute” it. Then, they dismiss it as a fable when their challenge fails. Nice try! They will continue to fail because the Bible is the true, infallible word of God.
Josephus, Antiquities of the Jews, Book 2, Chapter 14, Part 1