With federal and state budgets stretched to the limit, government officials increasingly are turning to private donations to help underwrite maintenance and restoration projects at the most popular state and national parks, San Jose Mercury News reports.

Of the $13.5 million spent on a recently completed project to restore hiking trails in Yosemite National Park, for example, $10.5 million came from private donations raised by the Yosemite Conservancy. In New York City, the Central Park Conservancy provides 85 percent of the park's $37 million annual operating budget out of donations and investment income. And in San Francisco, the Golden Gate National Parks Conservancy is overseeing a $22 million project to build new trails, upgrade a campground, and construct scenic overlooks at the Presidio that is funded by the Evelyn and Walter Haas, Jr. Fund.

With the national parks system facing an $8 billion maintenance backlog, private donations are an effective way to fund high-profile projects, say supporters of the national parks system. But they should not be viewed as a replacement for government funding, said Ron Sundergill, Pacific region director for the National Parks Conservation Association, an advocacy group. "The money is there in the Bay Area. And Yosemite is an iconic park," said Sundergill. "But the smaller parks, and the parks in rural areas, what happens there? It's really critical that the public funding stay."