Joseph Alosso, the superintendent of the Oak Bluffs wastewater treatment plant, has announced his retirement.

Mr. Alosso, 50, told the Gazette Thursday that his last day at the plant will be May 18. He said he informed the board of selectmen and the wastewater commission about his decision at the end of April.

“I’ve been doing this out here for 25 years, and I’ve accomplished a lot,” he said, adding that he enjoyed his job. His kids are getting older, he said, and this would be a good time for a career change. He said he wasn’t sure what the future holds — whether he will stay on the Vineyard or go elsewhere — but said he wants to continue working in the waste treatment plant field. Mr. Alosso said he qualifies for retirement benefits with the county.

Mr. Alosso concurrently worked as the director of the Edgartown wastewater plant until February. He resigned from his position after a report by a special prosecutor detailed poor management and record-keeping practices at the plant.

Around the same time, the Oak Bluffs wastewater commission moved to eliminate his job, saying the plant superintendent position was superfluous. In the end, with the commission lacking the authority to make such a decision, Mr. Alosso kept his job.

He said the vote did play a part in his decision to leave. “Anyone that works likes to have some sense of support, and likes to know they have the support of the board that’s overseeing where they work,” he said, and he took the vote as a no-confidence vote.

But as he sees it, if his employees can carry on without him, it means he’s trained them well.

“I believe we’re in a good place,” he said, adding that he’s excited about the future.

“I’m not leaving on a sour note, I’m leaving on a happy note.”