From Alaska's Bristol Bay to China's Lake Tai, we present this year's outstanding environmentalists

For nearly two decades, we've been celebrating the accomplishments of impassioned individuals working to protect their precious corners of the world. These tireless activists are determined to preserve not only the health of the environment but also the health (and the livelihood) of the local people, and they often carry out their mission at considerable personal risk. This year's winner is no exception: He has spent the past 16 years fighting to clean up the industrial pollution that is poisoning one of China's largest lakes, the primary water source for two million people, and he has paid dearly for his dedication. All four finalists, including another Chinese environmentalist concerned with critical water issues, are heroes within their communities but are little known beyond them. It is an honor to bring their efforts to the world's attention.

Winner: Wu Lihong
Devastating pollution in one of China's largest lakes prompts a small-town salesman to take action. Dorinda Elliott reports on his perilous path

Wu Lihong and fellow environmental activist Chen Faqing used to joke about going to jail. The two grassroots warriors, farmers born in villages surrounded by rice paddies in Jiangsu Province, knew that they were taking huge risks by challenging the local authorities responsible for polluting the nearby rivers that feed Lake Tai. As a boy, Wu swam in the enormous pristine lake, which was exalted by Tang dynasty poets. Painters and scholars on their way to the teahouses in Hangzhou used to stop on its beaches to rest, inspired by the majesty of the craggy shoreline and the waters lapping against bamboo forests. But in the last two decades, the lake's poetic past has been symbolically washed away in China's new commercial frenzy. Today, the 935-square-mile lake, the lone source of drinking and bathing water for two million people, lies in the middle of the country's most industrialized region—the workshop of the world—and the joke between the two friends has become a harsh reality. In April, Wu Lihong was arrested and charged with extortion, and in August, he was sentenced to three years in prison. A month earlier, while Wu was still awaiting trial, I went to a village near Lake Tai, where Chen showed me plastic bottles of polluted lake water collected by his friend before the arrest. "People like Wu are pushing for real change in this country," Chen said, shaking the bottles filled with brown, yellow, black, and even orange water. "He raised awareness of the environmental problems here, but we are up against rich corrupt bosses and officials."

The next day, at Turtle Head Park, where I boarded a ferry with dozens of Chinese vacationers, the lake water along the beach resembled thick, oily paint. The color was an eerie neon green. "What's that stinky smell? It's disgusting!" uttered one tourist from Sichuan, who had come with her son on summer holiday. A fishy chemical odor was wafting up off the lake. "Blue-green algae," said a local tourist. A tour guide told us that the government is trying to fix the problem, but he was afraid the cure might kill all the fish in Lake Tai.