MainStreet is on a mission to find the charitable organizations most worthy of your donations. We focus on their effectiveness and the amount of money they budget for actual good deeds, as opposed to that which goes to overhead.

This week we're looking at The Nature Conservancy.

President Obama’s American Reinvestment and Recovery Act promises up to $19 billion for clean water, flood and environmental restoration projects in the U.S. But when it comes to protecting the environment, the federal government can’t do it alone, and there's the rest of the world to think about, too. That’s where this Arlington, Va.-based organization comes in.

Who they are and what they do: The Nature Conservancy is one of the largest environmental nonprofits in America. In the 58 years since its founding, the conservancy has been able to save more than 119 million acres of land and 33 million acres of marine areas in places as varied as Montana and Micronesia through outright acquisition.

“Our strength lies in big projects, such as our $1 billion dollar Montana Legacy Project and a $210 million dollar acquisition of land in the Adirondacks,” says Bill Ginn, the chief operating officer.

Billion dollar real estate deals may seem out of place in the current economic climate and even unusual for a non-profit. However, using the organization’s $1 billion endowment as equity, the conservancy is able to save wildlife and protect biodiversity in more than 30 countries, support scientific research in the field of climate research and empower indigenous people throughout the world to advocate for the responsible use of natural resources.

How they spend your donations: Saving the world isn’t cheap, and while The Nature Conservancy has more than $4.9 billion in total net assets, according to its latest statement of activities, the organization depends on donations for its operating budget, calculated at $500 million last year. “In the end, our endowment provides only a small portion of available cash,” says Ginn. “If you spend that equity and there’s no repayment, you’ll go broke.”

According to financial statements for fiscal year 2007-2008, the conservancy spent more than $800 million, or 80% of its total revenue, on projects directly related to its mission. Some 12% of those funds went to administration and 8% to fundraising and membership development.

The non-profit currently holds a four star rating from Charity Navigator, the country’s largest independent charity evaluator. According to Charity Navigator, the conservancy’s revenue growth and program expense growth exceeds the rate of inflation, meaning it has expanded its programs and services over the last several years. And the charity has nearly one year’s worth of working capital, which is an important cushion to fall back on in the current economic climate.

Criticisms: The Nature Conservancy recently reported a $137 million dollar loss on its investment portfolio and earlier this month, announced it was cutting 400 jobs, roughly 10% of its staff. Jim Petterson, chief communications officer, attributed the cuts to the “poor economy and a substantial decline in contributions.” But Petterson insists outreach programs will not be compromised and says fundraising efforts are strong, as the conservancy pushes to raise $1.6 billion by July of next year. So far, the charity is about halfway to its target.

In the past, the conservancy has also taken flak for its ties to corporations, with critics accusing the charity of being overly reliant on big businesses for money. While the conservancy receives support from corporations and foundations, Petterson says much of that money goes toward capital costs, used for things like land acquisition. Petterson says individual donations are vital to programs and workers.

How to donate: Projects for 2009 include leveraging resources to conserve major areas of marine life in the Caribbean and a renewed focus on protecting grasslands in Africa. Not only does the organization plan to continue to maintain existing land and water acquisitions, but Ginn and the charity’s leadership also plan to push the Conservancy into taking a larger role in climate legislation advocacy and to strengthen its standing as a resource for policymakers and concerned citizens.

If you’re interested in making a donation or learning about what you can do to protect the environment, visit The Nature Conservancy online.

MainStreet Staff Writer Carl Winfield contributed to this report.