After six years as the town’s water superintendent, Neal Merritt has resigned to become head of water operations for the Hanover Department of Public Works. Merritt, who lives in Hanover, begins his new job Monday. “It was a tough decision to leave Hanson, but it was an opportunity I couldn’t pass up,” he said. “It’s a bigger system with more responsibilities.” Before starting his Hanson job in February 2007, Merritt spent 10 years as facilities manager for the Norwell Water Department. The Hanson Board of Water Commissioners is conducting a search for Merritt’s replacement, and applications are being accepted through April 30.