Years ago, people dumped old paint cans on this bank.

Rain washed paint into the river, so the water was not clean, and fish died.

Paint cans on the bank, and a streak of paint running into the water.

Is dumping the cans helpful or harmful to the river's living things? It is harmful: it takes away clean water.

Then other people picked up the cans and took them away.

Rain no longer washed paint in, so the water stayed clean and the fish lived.

People lift the paint cans and the trash bags off the bank into a truck.

Is picking up the cans helpful or harmful? It is helpful: it brings back clean water.

When what people do keeps the ecosystem healthy, or makes it healthier, we call it beneficial. Beneficial means helpful.