We all need clean water. People need it to grow crops and to operate factories, and for drinking and recreation. Fish and wildlife depend on it to survive. Many different pollutants can harm our rivers, streams, lakes and oceans. The three most common are soil, nutrients and bacteria. Rain washes soil into streams and rivers. The soil can kill tiny animals and fish eggs. It can clog the gills of fish and block light so plants die. Nutrients, often from fertilizers, cause problems in lakes, ponds and reservoirs. Nitrogen and phosphorus make algae grow and can turn water green. Bacteria, often from sewage spills, can pollute fresh or salt water.