A House bill to restart the process of making Nevada’s Yucca Mountain a permanent repository for nuclear waste would increase spending by $260 million over the next 10 years, the Congressional Budget Office said Friday in a report that acknowledges some uncertain numbers.

The CBO’s score could be a hurdle for the Yucca bill by forcing its backers to offset the cost by cutting other federal spending under pay-as-you-go budget mandates. The bill moved out of the Energy and Commerce Committee with surprisingly bipartisan support considering how the issue had divided Capitol Hill while Sen. Harry Reid of Nevada was majority leader. Reid didn’t seek reelection in 2016.

Among its key provisions, the bill would provide incentives in the form of federal dollars for infrastructure improvements to states and communities willing to host the nuclear waste at temporary storage sites and the long-term disposal facility at Yucca Mountain.

According to the CBO, those benefit payments account for the bill’s 10-year, $260-million direct-spending increase. The agency also noted that the 10-year increase would have little effect on the long-term costs of the nation’s existing waste disposal responsibilities under the Nuclear Waste Policy Act of 1982, which are likely to stretch through much of the 21st century and cost nearly $100 billion.

“In general, CBO expects that enacting [the bill] would not significantly change the overall magnitude of the long-term costs the government will incur under the NWPA (tens of billions of dollars over multiple decades),” the report said. “However, relative to CBO’s 10-year baseline projections, we estimate that enacting the bill would increase direct spending over the next 10 years.”

The math behind the score becomes a little muddled, the CBO acknowledged, because of the difficulty of factoring in reduced federal liability for not delivering on its promise under the nuclear waste act to provide nuclear power plants with a central repository for their spent fuel. That radioactive waste is now being stored at plant sites.

“Estimates of the government’s remaining liabilities are uncertain and depend critically on when and how DOE begins to accept waste and how long eliminating the backlog will take,” the report noted, adding, however, that “as long as DOE remains behind schedule, the government will continue to incur liabilities.”

DOE estimated in 2016 that its legal liabilities resulting from its failure to move the waste would total $25 billion.

For proponents of the bill, the CBO score shows the benefits that the bill would provide the government as it addresses the waste backlog.

“The committee appreciates CBO’s recognition that the enactment of the legislation could result in significant long-term savings to the federal treasury enabling DOE to finally fulfill its legal obligations,” an Energy and Commerce spokesman said. “The direct spending is primarily associated with benefits for the state of Nevada. We expect members recognize the value of a constructive dialogue with the state.”

A Yucca Mountain effort gained steam this year after the Trump administration expressed interest in renewing the project. Those efforts, however, are limited as appropriations for nuclear waste disposal have halted in recent years.

While Yucca Mountain had been the de facto location, as designated by a 1987 federal law, the Obama administration halted the process for opening the Yucca facility in 2010, citing intense local opposition, led in part by Reid. In its place, it looked to advance an interim storage program, but Congress never appropriated the necessary funding to launch a pilot facility.

Nevada lawmakers have vocally expressed bipartisan opposition to any potential Yucca Mountain resurrection, usually citing the cost and potential effects of shipping the waste across the country.

Rep. Dina Titus, a Democrat who represents much of Las Vegas, said in a statement Friday that the CBO report “is seriously flawed.”

“It does not take into account the cost of building the Yucca Mountain repository — a figure that’s estimated at more than $95 billion,” Titus said. “It ignores the fact that the Nuclear Waste Fund, which is to pay for the project, will diminish in the coming years as older nuclear power plants shut down. It also projects costs for only 10 years without accounting for the lifetime of the project which is supposedly designed to safely contain nuclear waste for 10,000 years.”

Titus, instead, pitched her own bill, which would advance a nuclear waste disposal site only with the signoff from the state and local government.