WATERBURY, Vt. – Efforts to make OxyContin harder to abuse have succeeded in Vermont, the top state police drug investigator says, but one notable result has been addicts switching to an older scourge: heroin.

Lt. Matt Birmingham, head of the Vermont Drug Task Force, likened the situation to Whac-a-Mole. Once one problem is addressed, another resurfaces.

Statistics provide another glimpse of Vermont’s growing heroin problems.

Deaths attributed in whole or in part to heroin overdose averaged less than 2.5 per year from 2004 to 2010.

There were nine in 2011 and six so far this year, according to figures provided by the state Health Department from the state Medical Examiner’s Office.

Investigators, drug counselors and others combating drug abuse were elated two years ago when OxyContin’s manufacturer, Purdue Pharma, reformulated the drug, Birmingham said in an interview. “Thank God,” he said.

OxyContin was designed for use by cancer patients and others suffering serious pain. It was to be taken every 12 hours, with the pill designed to release oxycodone into the body gradually.

Addicts were chewing the pills or grinding and snorting them for an instant high.

The new formula turns the pills into a gummy mass when they’re ground up, making them much less appealing to addicts.

But in the past two years, heroin has come to the fore in Vermont, with use spreading into some high schools.

“Unfortunately, the younger kids think they can start by snorting heroin,” a method that avoids the stigma and fear surrounding possibly dirty needles, Birmingham said.

“You can get addicted all the same,” he said adding that young people “generally end up injecting once they get a full-blown addiction.”

In addition to spreading to a younger group of users, heroin is circulating more widely in Vermont’s rural areas.

In the rural southeastern Vermont town of Chester, police raided an apartment in early October and arrested nine people.

They also seized $18,000 in cash, heroin with a street value of $20,000, crack cocaine worth $6,200 and OxyContin pills valued at $4,000.

Birmingham said drug distribution networks in the state appear to have become better organized than they were a decade ago.

In the past, people would come into Vermont with a shipment of drugs and set up shop in an addict’s house to sell them until the supply ran out.

“Now we’re seeing kind of organized networks within the state that some of the dealers can stay in New York City or Albany and wherever the source areas are and just sort of keep the flow going to the established networks in Vermont. So that concerns us greatly,” he said.

The response must combine law enforcement, education and treatment for addicts, Birmingham said.

“Law enforcement realized very quickly that we cannot solve this problem at all by arresting our way out of it. It’s just not going to happen,” he said. “As long as there is a demand here for heroin and opiate products, the supply will just keep coming. And you’re just not going to stop it unless you build a 20-foot fence around the state.”