The Republican-controlled Congress allowed the country’s most popular parks program, the Land and Water Conservation Fund (LWCF) to expire Sunday. The lapse threatens access to public lands and water and leaves many potential projects in limbo.

“The Land and Water Conservation Fund is the most successful land conservation program in our nation’s history. Congress’s inability to prevent its expiration is a stunning failure and a betrayal of more than a half century of broad bipartisan support,” Colin O’Mara, president and CEO of the National Wildlife Federation, said in a statement. “America’s wildlife heritage, outdoor recreation opportunities and public lands are the envy of the world and drive our $887 billion recreation economy.”

The Land and Water Conservation Fund provides funding to protect parks, forests, cultural heritage sites, and water resources, at zero expense to taxpayers. The fund, which is paid for through revenues from offshore drilling, was passed in 1964 and has financed projects in all 50 states.

Money from the fund is used to protect lands and recreation access across the board: from local baseball fields and trails, to purchasing private land inholdings within national parks.

With the lapse of the fund, the authority to carry out current LWCF projects remains authorized, but any new revenue from offshore drilling stops going into the fund, meaning new and upcoming projects will likely not have funding to proceed.

The Center for Western Priorities estimates that with this lapse in funding, at least 318,000 acres of deserving lands are at risk of being lost to development.

The LWCF is authorized to receive $900 million in revenue each year, but year after year Congress has shortchanged the fund, leaving it with about half of what is promised. This is the second time in three years that Congress has allowed the program to expire.

“It’s outrageous that the Republican-led Congress is allowing the Land and Water Conservation Fund to expire,” said Gene Karpinski, president of the League of Conservation Voters in a statement. “LWCF has bipartisan support in both chambers of Congress. Its expiration is a clear failure of leadership, starting with House Speaker Paul Ryan and Senate Majority Leader Mitch McConnell to even schedule votes. Communities need Congress to fix this and save America’s best parks program.”

Part of the reason the fund was left to expire is that Secretary of the Interior, Ryan Zinke, and Republicans have repeatedly attempted to frame it as an “either/or” choice between investing in the LWCF and addressing the National Park Service’s (NPS) backlog of maintenance projects. In fact, despite paying lip service in support of LWCF, Secretary Zinke’s budget recommended zeroing out funding for LWCF, while at the same time proposing a new fund to pay for infrastructure in national parks.

While the NPS’ $12 billion backlog is not unimportant, the price tag of critical, high-priority needs appears to be inflated. Moreover, the maintenance needs of NPS and other public lands agencies could be swiftly addressed if Congress were to provide adequate funding through its normal appropriations process, rather than establishing a separate new program that threatens to divert money away from the LWCF.

Despite the lapse in funding for LWCF, there are currently bills to permanently reauthorize the fund moving in both the House and Senate. On September 13, the House Committee on Natural Resources passed a deal to reauthorize LWCF, though it did not include any guarantees on funding.

The Senate Energy and Natural Resources committee will have a hearing on a bill that would both permanently fund and reauthorize the fund on Tuesday. But with the House on recess until after the November elections, there is no clear path for the bills to see floor time in the near future.

Jenny Rowland is a senior policy analyst on the Public Lands team at the Center for American Progress. ThinkProgress is an editorially independent news site housed within CAP.