The teenage boy accused of setting the Columbia River Gorge ablaze last summer most likely will get community service and probation, not an extended stay in one of the state's juvenile prisons, if he enters a plea next week as expected.

The harshest part of the penalty mostly likely will be an order to pay restitution, which could easily be in the tens of millions of dollars, though he probably would be able to cover only a tiny fraction of the costs.

The Vancouver teen, who was 15 at the time a witness reported seeing him throw a "smoke bomb" into the bone-dry brush along the Eagle Creek trail, is set to appear before a Hood River County Circuit Court judge.

Under juvenile rules, his probation could last a maximum of five years, say experts familiar with the juvenile justice system.

If the judge does decide to sentence him to juvenile detention, it probably would be for no more than eight days. Although sending the teen to one of the state's juvenile correctional facilities for a year or possibly more is an option, legal observers say that's a highly unlikely outcome.

The Oregonian/OregonLive spoke to several legal authorities who reviewed the case but asked not to be named because of the sensitive nature of the case.

Police and prosecutors have withheld the teenager's name, saying he and his family faced an immediate and virulent outpouring of condemnation on social media after detectives announced that they had a suspect in the fire. They said they were worried about his safety and have released few details of the investigation since.

Before charging him last fall, the Hood River County District Attorney's Office had the option of pursuing felony first-degree arson charges in adult court that could have resulted in a mandatory 7 ½ year prison term under Measure 11.

But among other lesser crimes, prosecutors decided to charge him with misdemeanor reckless burning. By its very definition, that crime indicates that prosecutors believe the teen didn't mean to start the fire. Rather, the charge acknowledges their belief that he ignited the blaze by his reckless actions.

The 48,000-acre blaze racked up a firefighting bill of at least $20 million, not including extensive restoration that will take years to complete.

The judge is obligated under state law to order that the teen pay the full amount of restitution, experts say, though it will be virtually impossible for the teen to earn that kind of money in his lifetime.

He will be obligated to pay for the next 50 years, under state law. The Oregon Department of Revenue could garnish his bank accounts or paychecks. If he's due refunds on his tax returns, the state could take those. If he wins the lottery, the state also could collect all of his winnings.

He could work out a payment plan with the court. They're relatively common. One example is a 23-year-old Warm Springs woman who purposely started a brush fire in central Oregon in 2013 to give her "bored" firefighter friends something to do.

She likely will be on the hook for restitution for the rest of her life. The fire spread to more than 51,000 acres. A judge in 2014 ordered Sadie Renee Johnson to start paying the U.S. Bureau of Indian Affairs $7.9 million in installments of $50 per month.

Oregon law, ORS 30.765, states that parents can be held liable for up to $7,500 for any intentional or reckless act of their children that has harmed people or property. But the law carries a kicker: It appears to allow $7,500 to be collected per "claimant."

Attorneys contacted by The Oregonian/OregonLive said that could mean that any of the thousands of people affected by the Eagle Creek fire could seek $7,500 a piece from the Vancouver teen's parents.

Oregon's juvenile justice system is designed to give minors second chances.

Advocates for juvenile justice system reform said the teen's likely sentence is the type of "consequence" most likely to teach him a lesson and redirect his behavior.

They contend convicting juveniles of felonies in the adult system or incarcerating them can do more harm than good because adolescent brains haven’t fully developed and young offenders have a greater chance of learning from their mistakes than adults.

Some critics, however, argue that the light-handed touch has been a failure, with Oregon floundering under high rates of juvenile drug offenses and property crimes.

But Bobbin Singh, executive director of the Oregon Justice Resource Center, said he's seen youths who have completely turn their lives around after committing terrible crimes.

Yet, if they were convicted in the adult system as a juvenile and have a felony record, they can have difficulty getting a job or housing, he said. That hinders their progress, he said.

"Do we want to create this second-class citizen at such a young age?" Singh said.

Because the teen accused of setting the Eagle Creek fire is being prosecuted in the juvenile system, his conviction record will be sealed and it won't be available to future colleges or employers.

Jim Ryan of The Oregonian/OregonLive staff contributed to this report.

-- Aimee Green