"Given Centralines recently commenced contractual negotiations to provide the distribution services to the Ruataniwha Water Storage Scheme, Mr Robinson has acted to ensure no conflict of interest exists.
"In his nearly 10 years of service, Mr Robinson brought a wealth of knowledge and experience to the board, and his contribution will be greatly missed. We wish him all the best for his future ventures."
Jon Nichols, a Centralines board member since July 2011, has been acting chairman during Mr Robinson's absence and has now been confirmed in that role.
A business consultant and chartered accountant, Mr Nichols has been involved in a number of strategic growth, regulatory and performance-based initiatives for infrastructure businesses, Mr Setter said.
He serves on the boards of Port of Napier and Palmerston North Airport Limited, and is an independent member of the Hastings District Council audit and risk committee.