The state's Public Health Council on Wednesday signed off on the planned affiliation or merger between Lahey Clinic and Northeast Health System, provided the new nonprofit corporation—Lahey Health Systems—keeps Northeast's Addison Gilbert Hospital services at current levels for a minimum of three years and conducts a community health needs assessment for going forward. The Public Health Council's approval was the last that Lahey and Northeast needed before the non-profits join in their partnership. The affiliation will create a $1.5 billion, integrated regional health system along an axis from Gloucester to Burlington.