Montana officials say federal highway money will cover less than a third of the state’s $15.8 billion in transportation needs over the next decade, but there are no plans to significantly boost state spending to cover the anticipated shortfall.

Other states have turned to alternatives such as toll roads or other user fees to supplement transportation money from the federal government.

Such ideas makes less sense in Montana due to the relatively light traffic in the largely rural state, according to Montana Department of Transportation Director Mike Tooley.

That leaves the state heavily dependent on federal spending, which accounts for 87 percent of highway construction money in Montana.

Tooley says some roads could start to deteriorate if spending remains flat as projected.

“The numbers just don’t add up and eventually you’ll notice it on the highway itself,” he said. “Pavement conditions might deteriorate, bridges that we need to replace will climb in number, and we won’t have all the resources we need to address them.”

Money from the federal Highway Trust Fund declined in Montana by just over 2 percent during the past five years on an inflation-adjusted basis, to $722 million in 2013.

That’s a lesser decrease than the 11 percent reduction nationwide. Yet it occurred as the state’s population and needs have grown, particularly in the Bakken oil-producing region along the Montana-North Dakota border.

Montana Gov. Steve Bullock is pushing a $391 million public works package in the state Legislature that includes only a handful of roads projects. Most of the money is dedicated to sewer systems, school facilities maintenance and other non-transportation projects that Tooley said take priority.

Meanwhile, the current federal Highway Bill is set to expire in May. In recent years, it has been reauthorized on a short-term basis.

Even if the dollar amount doesn’t increase as Congress again considers the measure, Montana U.S. Sen. Jon Tester said he wants a five-year reauthorization of the bill to help states better plan for long-term needs.

Under the current funding formula, Montana gets a lot of bang for its highway buck, receiving $2.58 in federal funding for every $1 it deposits in the federal Highway Trust Fund, according to state officials.

Tester said lawmakers from other states want to alter that formula because they feel their states are getting shortchanged. The Democrat declined to give further details, but said the push for changes to the formula underscores the need for highways to be a federal responsibility so less-populous states aren’t disadvantaged.

“There are some back in Washington that want to get every penny back that they put in [the trust fund],” he said. “That kills rural states.”