Water Corporation chairman Mike Hollett has tendered his resignation, citing business and family interests, just two months after being reappointed to the role. Deputy chair David Lock will act in the role until a permanent chair is appointed.
Water Corp announced the resignation on its website last week but has not disclosed further information as to Mr Hollett's sudden departure.
Minister Dave Kelly has stated he is unable to comment because of legal issues.
"This is just another in a long list of events where the government refuses to tell the public the truth," Mr Sibma told reporters this morning.
He said the state government's refusal to comment on Mr Hollett's departure invoked further speculation and questions from the Western Australian public.
"Public confidence must be restored in the Water Corp's operations because it delivers such an essential service."
He was the chief executive of National Lifestyle Villages from 2008 to 2012.
Mr Lock was appointed to the board as a non-executive director in 2014 and was appointed as deputy chairman in 2017.
He is also the chairman of Water Corporation’s audit and risk committee.