Contaminated runoff kills aquatic life. Metals and other toxins are absorbed in the flesh of fish and shellfish and are dangerous when eaten. Bacteria, parasites and chemical toxins contaminate recreation areas and drinking water, which cause major illness and sometimes death. Most streams, lakes and coastal waters surrounding large cities are too polluted for people to use. If development of cities continue without care and management of pollution and the natural watershed, most or all fish and aquatic life will be killed, entire ecosystems will be destroyed and it will be nearly impossible to find uncontaminated water that is safe to use or drink.