Pigs really are dirty--but only because humans make them that way. Hog farmers crowd the animals, dose them with antibiotics, and spray out their drug-tainted feces, wreaking havoc on fields, streams--and you. Pigs huddle atop grates that allow waste to drip through.

On many hog farms, the waste runs into a storage lagoon from which it is pumped and sprayed on surrounding fields.

In 1995 one such lagoon spilled into a nearby river, killing 10 million fish and contaminating drinking water. Last July North Carolina became the first state to ban building new lagoons on hog farms.

Storage lagoons take on an electric color from bacterial reaction to hog feces.

Such lagoons can cover up to 7.5 acres, albeit on a farmer's own property.

The problem: Overflow and sprayed waste can find their way into local wetlands, where fecal matter triggers algal blooms that choke out other aquatic life.

Seen from about 700 feet up, this storage lagoon swirls with feces, afterbirth, pesticides, bacteria, and hormones. In the United States, hogs produce more than 119 million tons of waste a year.