Water Pollution

As technology improves, scientists are able to detect more pollutants, and at smaller concentrations, in Earth’s freshwater bodies. Containing traces of contaminants ranging from birth control pills and sunscreen to pesticides and petroleum, our planet's lakes, rivers, streams, and groundwater are often a chemical cocktail.

Beyond synthetic pollution, freshwater is also the end point for biological waste, in the form of human sewage, animal excrement, and rainwater runoff flavored by nutrient-rich fertilizers from yards and farms. These nutrients find their way through river systems into seas, sometimes creating coastal ocean zones void of oxygen—and therefore aquatic life—and making the connection between land and sea painfully obvious. When you dump paint down the drain, it often ends up in the ocean, via freshwater systems.

In the developed world, regulation has restricted industry and agricultural operations from pouring pollutants into lakes, streams, and rivers. Technology has also offered a solution in the form of expensive filtration and treatment plants that make our drinking water safe to consume. Some cities are even promoting "green" infrastructure, such as green roofs and rain gardens, as a way to naturally filter out pollutants. But you may find a different picture in parts of the developing world, where there is less infrastructure—politically, economically, and technically—to deal with the barrage of pollution threats facing freshwater and all of the species that rely on it.

Fast Facts

• In developing countries, 70 percent of industrial wastes are dumped untreated into waters, polluting the usable water supply.

• On average, 99 million pounds (45 million kilograms) of fertilizers and chemicals are used each year.

• Portland, Oregon, is actively pursing “green roofs” and “green streets” to prevent sewer overflows into the Willamette River. Chicago, Illinois, now has more than 517,000 acres (209,222 hectares) of vegetated roofs—more than any other U.S. city—which are helping to catch storm water, cool the urban environment, and provide opportunities for rooftop gardens.