Electric car owners in Nevada could soon be required to pay a 10 percent tax when charging their vehicles under legislation proposed by Republican state Sen. James Settelmeyer.

Introduced on Monday, SB114 would impose a 10 percent surcharge on electric vehicle charging ports and deposit the tax funds in the State Highway Fund, the budgetary account for road construction and repair funded primarily by gasoline taxes. If approved, the bill would take effect in 2020.

In an interview, Settelmeyer said he was bringing the bill as several of the state’s existing electric vehicle charging stations, mostly built over the last four years through federal grant funds, were closing out a required 2-year period of free charging — meaning drivers now need to actually pay to charge their electric vehicles at charging stations.

“If you’re being able to earn money off of this, then 10 percent of that should go to the state to the highway fund,” he said. “Again, to try and help pay for the lack of funding due to the fact they’re electric.”

It’s unclear whether any other states place a surcharge on electric vehicle charging stations, although a handful of states levy registration fees on electric vehicles or tax them based on total miles traveled.

According to a tally by the Sierra Club, at least 17 states have adopted some kind of additional registration fee for electric vehicles to help fund road repairs. The environmental group is opposed to electric vehicle registration fees, saying it unfairly targets electric car owners and fails to raise enough funds to substantially affect road and infrastructure spending.

“Nevada must stand up for its electric vehicle drivers and the growing EV economy,” Sierra Club Nevada Campaign Representative Elspeth DiMarzio said in an emailed statement. “Special interests want to destroy that market with punitive fees, and impede our progress on the transportation pollution problem.”

Settelmeyer also said he had requested a bill draft to create an optional electric vehicle license plate, which would cost drivers $150 with the funds being split equally between the state Highway Fund and electric vehicle charging infrastructure and administration.

Settelmeyer said he was opposed to mandating fees — noting the license plate would not be mandatory and drivers could get around the 10 percent surcharge by charging at home — and said he didn’t want to place unwieldy barriers to electric vehicle ownership.

“People had a reasonable reliance that they wouldn’t have gigantic increases and they’d be able to save some money,” he said. “So if we go too far, then we’re the other way and we’re discouraging people from buying electric cars.”

The bill has not yet been scheduled for a hearing. Tesla, a major electric car manufacturer, declined to comment on the proposed legislation.

Under former Gov. Brian Sandoval, Nevada launched an “electric highway” initiative in 2015 that aimed to use federal grants to install electric vehicle charging stations in remote outposts of the state and reduce so-called “range anxiety” for drivers of electric vehicles.

According to data compiled by the Alliance of Auto Manufacturers, Nevada’s percentage of drivers with electric cars (1.53 percent) is below the national average of 2.24 percent, with 1,068 electric vehicles registered in the state as of 2017.

Adding additional fees on electric vehicles may have bipartisan support. In an interview last week, Democratic state Senate Majority Leader Kelvin Atkinson said he was “supportive of efforts” to make electric vehicle owners pay into road repair budget accounts.

“They do a little less damage because they’re not as heavy, but they’re doing damage to the roads, and so how do we get them to participate in the roads?” he said. “In other states, [cities such as] Chicago and Los Angeles, they have a state income tax and that’s how they pay for their roads, [but] we don’t have a state income tax, so it has to come through [tax] dollars and I think every car on the road should be participating in that. I’ve made that no secret.”

Atkinson said he wasn’t ready to support any proposal that would tax electric vehicles based on miles traveled, a proposal entertained by other states.

Democratic Sen. Patricia Spearman and Assemblywoman Daniele Monroe Moreno both confirmed Wednesday that they are working on measures related to electric vehicles, but said it was too early to discuss the specifics of their individual bills.