ROCKLAND, Maine — Nearly two years after a company first proposed opening a methadone clinic in Rockland at the same location as one closed due to illegal drug activity, final federal approval is near.

The last remaining hurdle for the opening of a methadone clinic by Metro Treatment of Maine on Route 1 near the Thomaston town line is approval by the U.S. Drug Enforcement Administration. The DEA must approve a registration for operating a narcotic treatment program for the clinic to open.

Approval of the registration is “imminent,” according to spokesman Anthony Pettigrew of the DEA. The spokesman, however, declined to give a specific time frame.

The federal agency will review approvals given by the state, but it also has its own criteria for reviewing such applications, the agency spokesman said Thursday.

The final state approval was granted at the end of July.

Metro Treatment of Maine, part of Colonial Management LLC, has sought since the summer of 2011 to open a clinic at the site of the former Turning Tide methadone clinic.

Turning Tide was closed in 2010 a few weeks after the clinic’s owner and one of its drug counselors were charged with felony drug offenses.

At the time, an investigation by the DEA determined that Turning Tide’s “continued registration to dispense controlled substances constitutes an immediate danger to public health and safety.”

Based on the results of the federal investigation, the state permanently revoked the clinic’s license to operate.

Since its closure, patients have had to travel to other clinics in the state with the closest clinics in Portland, South Portland, Westbrook, Waterville and Bangor.

Metro Treatment of Maine has not said when it plans to open the new clinic if it gets final federal approval. The firm has estimated it will serve 400 patients.

A competing proposal for a methadone clinic in nearby Warren was dropped in October when CRC Health Group announced it would instead pursue its federal civil rights lawsuit against the town to recover damages for not being allowed to open when it had planned.

Rockland Police Chief Bruce Boucher this week said it has been a few months since he has talked with officials from Metro Treatment who plan to operate the new clinic. He said that a methadone clinic advisory committee has been created. The Rockland City Council voted in November to appoint James Pease, the supervisor of the Midcoast bureau of Maine Drug Enforcement Agency, to serve on the advisory committee.