The Flint Michigan Crisis began in 2014, when the water source for the city Flint, Michigan was changed to the Flint river. This is because the old water resource was filled with high amounts of led. That's why it was switched to the Flint river.
Hydrology is the science of water, on the waters movements, if water can be found on other planets beside Earth. Hydrology is also on how water can affect land in different ways or how land can affect water in different ways.
Watershed is when water drifts away carrying trash, chemicals, bacteria, and anything else that can harm or infect water. The water that carries all of these things will end up going into rivers, lakes, ponds, and other bodies of water.