WASHINGTON – Help may finally arrive for America's deteriorating national parks.

A bipartisan coalition of lawmakers is getting behind an effort that would tackle the $11.6 billion maintenance backlog eroding the country's most iconic attractions including Yellowstone National Park, the Grand Canyon and the Great Smoky Mountains.

Last week, the House Committee on Natural Resources approved The Restore Our Parks and Public Lands Act, a measure that would set aside for park repairs more than $5 billion from energy development royalties over several years that now flow into the general U.S. Treasury. The measure heads to the full House.

A similar Senate proposal, led by Republican Rob Portman of Ohio and Democrat Mark Warner of Virginia, would dedicate $6.5 billion in royalties for maintenance.

“As America’s beloved national parks buckle under the weight of broken pipes, crumbling roads and other incomplete projects, additional funding is crucial to keeping parks safe and accessible for the public," said Rep. Rob Bishop, R-Utah, who chairs the Natural Resources panel.

All but five of the country's 417 national park sites – which include historic landmarks, recreation areas and parkways – have some type of need, according to the most recent tally by the National Park Service (NPS).

More than two dozen, including the National Mall in Washington, Yosemite National Park in California and the Natchez Trace Parkway in Mississippi, have a backlog surpassing $100 million.

It's not just big-ticket items. Examples of disrepair that ruin the park experience are commonplace. And it's not just parkways offering majestic views or hiking trails that allow close encounters with wildlife. Critical infrastructure – sewer systems, visitor centers, bathrooms and campgrounds – dot the list of expensive fixes.

"The network of roads, trails, restrooms, water-treatment systems, drinking water and visitor centers are aging and are exceeding a capacity they were often never designed to hold and support," Lena McDowall, the National Park Service's deputy director for management and administration, told a Senate committee in July.

Among the examples:

•The inadequacy of the Big Oak Flat entrance at Yosemite, which welcomes about 1 million visitors annually, forces visitors to wait in long lines for services and restrooms, and space restrictions make it difficult for first responders to access the park during emergencies.

•The Hyde Park, New York, home of Franklin D. Roosevelt, a national historic site where the nation's 32nd president not only was born but where he is buried, has begun to crumble. The estate needs $10 million in maintenance, including repairs to its foundation, external finishes and interior paint and plaster, to return the home to its original character.

•Repairs to the 92-mile road that provides the only access to the heart of the Denali National Park and Preserve in Alaska are a major part of the national attraction's $52 million to-do list. Also on the list is a maintenance project for several buildings, including a kennel that houses the only sled dogs in the national park system.

•The Flamingo Lodge at Florida's Everglades National Park was shut down in 2005 after powerful hurricanes inflicted major damage. Plans have been drawn up to replace the landmark, but there's no money, leaving one of the nation's most visited national parks without a major lodging facility.

Previous efforts to come up with maintenance funding, such as selling naming rights on park features, raising fees significantly at highly visited sites and dedicating revenue from energy development, hit roadblocks.

A proposal by the National Park Service last year to double many fees at 17 of the nation's most visited parks during peak season died after fierce public opposition. A compromise was reached to raise fees by $5 at 117 parks. Although 80 percent of fee revenue goes directly back into the parks, the increase is not likely to dent the backlog much.

Democrats and environmental groups pushed back on another proposal tying park repairs to development of energy, such as offshore drilling, concerned it would encourage more production and consumption of fossil fuels that cause pollution.

"That was not a trade-off that needed to be made," said Rep. Raul Grijalva, D-Ariz., the top Democrat on the Natural Resources Committee, before last week's vote.

Although the billions the Restore Our Parks bill would raise cover only about half the backlog, national park advocates back the measure because it would be spent on the highest-priority needs identified by the NPS.

That list includes the deteriorating seawall protecting the Statue of Liberty, the failing pipe that serves as the sole drinking water source for visitors at the Grand Canyon’s South Rim and the ceiling of the Jefferson Memorial in Washington, where a net hangs to catch pieces of stone that may fall, according to the Pew Charitable Trusts.

Hurdles to passage remain.

Congressional budget rules require most measures to pay for themselves and not add to the deficit, meaning lawmakers would have to cut elsewhere to fund the park maintenance bill. A packed congressional agenda filled with competing priorities heading into the final weeks of the legislative session means even popular, bipartisan initiatives don't always get a floor vote.

Park advocates are optimistic because Interior Secretary Ryan Zinke made reducing the backlog a top goal.

The rebuilt attractions would more than pay for themselves, said Kristen Brengel, a lobbyist for the National Parks Conservation Association, an advocacy organization.

"This is an investment that we would make to put back into parks that not only bring immense value to the American public but bring in billions upon billions of tourism dollars," she said.