(CNN) - Spring officially starts Thursday. And as the snow melts, waterfalls gush, and plants begin to bloom, the country's national park system once again becomes a playground for millions eager to get back outside after a long, brutal winter.
Hundreds of those park sites were closed for more than two weeks during the federal government shutdown last fall. Five months later, some states are still dealing with unresolved financial costs related to the closures.
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During the second week of the 16-day shutdown, six states tapped into their own coffers to pay the federal government about $2 million to reopen several locations–and those states are still waiting to get their money back.
A bipartisan group of U.S. senators introduced a bill last week that would reimburse the states, but the bill's future is uncertain.
The shutdown started at the beginning of October, a time known as the fall "shoulder season" when tourists flock to national parks before the off-peak period kicks in. Acadia National Park in Maine especially gets busy in October for its fall foliage, while park guests in the American Southwest want to experience the desert climate in the cooler weather.
All told, the National Park Service closed 401 locations–including the 59 specially designated national parks–across the country and furloughed more than 20,000 employees. Businesses that rely on park tourism lost an estimated $500 million in visitor spending, according to a report by the Office of Management and Budget.
Worried about the crippling effects the closed parks were having on local economies, several governors reached an agreement to pay the NPS to put staff back into park sites and manage the locations as normal.
Arizona, Colorado, New York, South Dakota, Tennessee, and Utah each doled out cash to the federal government to open 13 sites from a range of one to five days, until the shutdown ended on October 16.
The states wired money to the NPS under the stipulation that reimbursement could only come with Congressional approval.
Tennessee paid $60,100 to reopen Great Smoky Mountains National Park, the most visited park in the country with more than 9.35 million visitors last year.
"The Smokies closing was like a BP oil spill for the Gulf, especially for places like Sevier and Blount counties, where the success of many small businesses relies on our country's most-visited national park," Sen. Lamar Alexander, R-Tennessee, said in a statement.
Of the six states, Utah paid the most, dishing out $999,432 to open parks for six days.
As with other funds spent during the shutdown, however, Congress was under no obligation to pay back the states.
"The states knew there was no guarantee they would be reimbursed, but they judged that risk to be worth taking in light of the enormous economic importance of national parks to state and local economies," said Theresa Pierno, the chief operating officer of the National Parks Conservation Association.
She added that Utah saw a return of 10:1 on the money it invested.
Months later, Congress still working on repayment
The new piece of legislation isn't the first attempt by lawmakers to reclaim federal funds for their states. A similar bill was introduced in the House and passed by the Natural Resources Committee by a voice vote in December, but it hasn't been taken up on the floor.
Republican leadership aides said the bill is still being reviewed and they have nothing new to announce for the schedule at this point.
A Senate version of the House bill, introduced by Alexander and co-sponsored by fellow Republican Sen. Orrin Hatch of Utah and Democratic Sens. Mark Udall and Michael Bennet of Colorado, was referred to committee last fall and was awaiting consideration when the new bill was introduced last week.
How are the two bills different?
The new legislation has more sponsors. Introduced by GOP Sen. Jeff Flake of Arizona, the bill is also backed by Republican Sens. John McCain of Arizona, Mike Lee of Utah, and Bob Corker of Tennessee. That's in addition to the four senators who co-sponsored the earlier bill.
Unlike the previous bill, the new legislation includes what's known as a "pay-for," a provision that explains where the $2 million would come from–making its prospects for moving ahead much higher. The senators propose that the National Park Service should foot the bill.
Rhea Suh, assistant secretary for policy, budget and management at the Interior Department, which oversees the NPS, said she would support reimbursing the states if Congress approved such legislation. Her support came in a written statement last month to the Senate Energy and Natural Resources Committee.
She's currently awaiting confirmation to a different post at the department–assistant secretary for fish and wildlife and parks.
"If confirmed, I commit to working with you and to other Members of Congress on legislation that would authorize reimbursement to the states for these donated funds," she wrote.
Sponsors of the new bill also hope to bypass the committee and bring the measure directly to the Senate floor.
But even if it does pass, it would still need to go through the House.
'Symbol for the entire government'
The national parks system became the face of the shutdown last fall. Outrage over "closed" signs and barricades at popular sites, reminded Americans again just how much they love their parks, a system that's often called "America's best idea."
As former NPS Director Denis Galvin testified in a House hearing in October, the parks receive outsized attention during a shutdown and "become the symbol for the entire government."
"They are an easy media target with powerful visual images and dozens of examples of unintended consequences," he said. "Yet the NPS budget is 1/15th of one percent of the total federal budget."
This wasn't the first time dysfunction in Washington led to such closures, and few believe it will be the last.
The previous major shutdown occurred in 1995-1996 during the winter, a far less busy time for most national parks. But thousands were still furloughed. The National Parks Conservation Association estimates local businesses lost $14 million per day, and parks were closed for 27 days.
Negotiations to have some states reopen national parks, like the agreements reached last fall, were cut short when the government itself got back to business.