It's not the population, it's the concentration.
In a drought, snakes will go to dog bowls, horse troughs and cattle tanks.
We've had colonies of cottonmouths migrate from drying creeks to the drainage ditch in our yard, kept a bit moist from our water softener and sprinklers.
I have made Olympic caliber leaps with my big toe in the past.. and have put on a few pounds, I may not clear the snake this time.
Adios,