AMHERST — After 15 years working in the district, Mark Jackson announced Thursday that he would retire as principal of Amherst Regional High School on Nov. 1.

Because he will be using accrued vacation time, Thursday was his last day, according to an email announcement from Superintendent Michael Morris.

“Although the timing may seem less than ideal,” Jackson said in an email announcement, “I believe that, with the district about to undertake several major initiatives, among them Strategic Planning, this is actually an appropriate time for me to step down.

“At retirement age, I feel responsible to make room for new leadership.”

Morris said in his announcement that Miki Gromacki, assistant principal at ARHS for the last 10 years, would take over as interim principal starting Friday. The district will begin a search for Jackson’s replacement in the winter or spring, Morris said.