... contamination of streams, lakes, underground water, bays, or oceans by substances, is harmful to living things. Water is necessary to life on earth. All organisms contain it; some live in it; some drink ... moderately pure, and they cannot survive if their water is loaded with toxic chemicals or harmful micro-organisms. If severe, water pollution can kill large numbers of fish, birds, and other animals, ... chemicals are biodegradable and quickly decay into harmless or less harmful forms, while others are non-biodegradable and remain dangerous for a long time. Heavy metals, such as copper, lead, mercury,...