The world's largest conservation non-governmental organization is a 63-year-old environmental activist group that has drawn 119 million acres of sensitive lands under its protective wings. It has amassed assets of $6 billion and now annually collects $500 million in donations from its one million members to fight the green fight.

The Nature Conservancy has 3,500 employees, 600 of them scientists, including 380 water-resource professionals with advanced degrees. Over the past several years, under the leadership of Mark Tercek, the president and chairman who came on board in 2008, it has expanded its strategy from acquiring and sequestering environmentally important land to identifying and influencing new development projects that have potential to impact freshwater resources. It now partners with planners and developers on selected projects to optimize outcomes for both humans and nature.