A study released Thursday said the national parks are worth about 30 times more what they cost to the American taxpayer each year.

The study was commissioned by the National Park Foundation, a charity benefiting the National Park Service. It reported the total economic value of the parks and programs is $92 billion annually, more than 30 times the $3 billion budget given to the service by Congress.

Approximately 1,000 people took a 12-page survey asking them to value the country's national parks. The study not only included how much is spent at national parks but how much respondents are willing to pay to preserve America's wild spaces.

One of the study's authors, Harvard University Professor Linda Bilmes, said the $92 billion annual value figure is conservative. "The parks are creating a value, a far greater value, than what we spend on them," she said.

Thirty-two percent of respondents said they would pay $150 per year more to make sure only some land was sold off, and 49 percent said they were willing to pay $400 per year to make sure no land was sold off.

Bilmes said the responses showed that even people who don't visit the national parks find them valuable. She said 95 percent of respondents said it's important to protect national parks and 85 percent said they benefit from the existence of national parks even if they don't end up visiting them.

"The public overwhelmingly supports the national parks, whether or not they visit," she said.

National Park Service Director John Jarvis hailed the study as an important look at the total picture of the impacts of the national parks.

Jarvis said the study is different than the one NPS does every year studying how much economic activity is done in and around the country's national parks. Those studies show about $30 billion is spent by people visiting national parks every year.

Bilmes briefed members of Congress on the study Thursday morning, and Jarvis said it will make a good talking point in the National Park Service's push for more funding from the federal government.

But even if Congress finds a way to spend more on the parks, the study's authors argued that a new way of funding the national parks is going to be needed in order to make sure programs and lands are well maintained. The national parks have a large maintenance backlog due to lack of funds and some programs have had to be cut in recent years as the budget is smaller now than it was in 2001.

Jarvis agreed that the study lends credence to thoughts that more funding from outside the federal government might be needed in order to maintain the national parks into the service's second century.

"We need to think about a more robust and sustainable financial model for the National Park Service," he said, "and that is a combination of federal appropriations, non-appropriated funds that are generated through sources like fees and philanthropy."