Acid mine drainage is like when someone leaves a mess at home that makes everything yucky and smelly.
Sometimes, people need to dig deep into the ground to get minerals like gold, silver, or copper. These minerals are found in rocks and dirt, and when people mine, they need to break, smash, and crush those rocks to extract the minerals.
But inside those rocks and dirt, there are also tiny particles of metal that can be harmful if they get into the water, soil, or air.
When the rocks and dirt are moved around during mining, those tiny metal particles can mix with the water and create a kind of yucky juice. This juice is called acid mine drainage because it's very acidic and can hurt things that live in water, like fish and plants.
When this yucky juice spills out of the mining area, it can flow into nearby streams, rivers, and lakes. Once it gets into the water, it can go a long way and make everything all yucky and smelly.
Because of this, people who mine need to be careful about how they dig and how they handle the rocks and dirt they mine. They have to follow rules to make sure the yucky juice doesn't spill into the water and harm animals and plants.