How does a beaver dam change a river?

Have you ever dropped a stick into a stream and watched it race away? Stream water splashes over stones and hurries along. Now picture a family of beavers stacking sticks and mud across that stream. They build a strong wall called a dam.

The dam stands in the way of all that rushing water. So how does a beaver dam change a river? Let's follow the water and find out.

First, the water hits the dam and cannot rush past anymore. The beavers pack every gap with mud, so only a little water seeps through. The rest piles up behind the wall, like bathwater when the plug is in.

Bit by bit, the water behind the dam gets deeper and deeper. The fast, narrow stream turns into a calm, deep pond.

In the calm pond, the water slows almost to a stop. Slow water cannot carry mud and sand along, so they sink to the bottom. The pond floor turns soft, and the water above it grows clear.

The beavers keep building, and the pond keeps rising. Soon the water reaches the top of the low banks along its sides. Where do you think the extra water goes next?

It spills out over the flat ground beside the river and soaks into the soil. The grass, roots and mud there stay soggy all year long. A soggy place like this is a wetland, which means land that stays wet and squishy like a sponge.

The wetland holds water the way a sponge does. In a dry summer, it lets that water out slowly. That way the stream below the dam keeps flowing instead of drying up.

The wetland also becomes a brand new home. Frogs lay their eggs in the shallow water, ducks paddle between the reeds, and fish hide in the deep pond. One beaver dam turns a quick little stream into a busy place full of life.

Here is our key word: wetland. A beaver dam holds back the river's water, so the water slows down, rises into a deep pond and spreads out into a wetland.

Sleep well, and maybe tonight you can dream of a quiet pond where busy beavers are building.