OLYMPIA — It will soon cost more to travel on a state ferry.

Fares are expected to rise in October but exactly how much and for whom are questions the Washington State Transportation Commission plans to tackle at its May 16 meeting.

The impetus for the price hike comes from state lawmakers. The 2017-19 transportation operating budget that passed last month requires Washington State Ferries to come up with an additional $8.4 million in revenue for day-to-day operations. If all those dollars come from higher fares, it would work out to an across-the-board increase of 2.5 percent.

On Tuesday, commissioners will consider recommendations developed by Ray Deardorf, planning director for Washington State Ferries. Greg Beardsley, a Vashon Island resident and chairman of the citizens’ Ferry Advisory Committee — Tariffs, will offer reaction from that group as well.

It is anticipated commissioners will come up with a fare increase proposal and schedule hearings to gather public comment on it. A final decision is expected in July or early August.

Deardorf declined to share details of his recommendation before delivering it to the commission. A state ferries spokesman said it might not seek to boost fares the same amount for all travelers.

“We will be presenting a proposal to the commission that meets the goal set by the Legislature but there will be structural changes in how we get there,” spokesman Ian Sterling said.

Beardsley said Friday he had not seen the department’s final recommendations but believed it would incorporate some suggestions from advisory committee members.

One of those is to have fare hikes take effect Oct. 1 this year and Oct. 1, 2018. Historically, the effective dates of increases are in October the first year and May 1 in the following year.

As for the financial components, he said the agency is considering a reduction in or end of the surcharge imposed on oversized vehicles. The committee has sought such a move for a couple of years.

And Beardsley said he thinks the agency will pursue similar-sized fare hikes for vehicles and walk-ons, unlike previous years when vehicles shouldered the greater share of the burden. He said he thought state ferry officials are considering increases this October of 2.9 percent for vehicles and 2.1 percent for passengers in cars and walk-ons.

“We don’t need to differentially charge passengers and vehicles,” he said. “I have argued for many years that the change in passenger fares is not going to change the nature of passenger behavior.”

State law empowers the commission to set fares for Washington State Ferries, which is the largest ferry system in the country. Nearly 23 million people ride the ferries each year. There are 20 terminals located on nine routes throughout Puget Sound. Two of the most heavily used routes are Mukilteo-Clinton and Edmonds-Kingston.

Fares have gone up nearly every year since 2007.

Commissioners in 2015 approved a 2.5 percent hike for vehicles and 1 percent for passengers in cars and walk-ons. Those increases occurred Oct. 1, 2015 and again May 1, 2016.

Those two price hikes resulted in drivers of a standard length vehicle—between 14 and 22 feet—paying an additional 70 cents for a one-way fare on the Edmonds-Kingston route based on a report Deardorf presented to commissioners. Passengers and walk-ons wound up paying 20 cents more for a one-way trip on that route.

Jerry Cornfield: 360-352-7623; jcornfield@heraldnet.com. Twitter: @dospueblos.