"It's a dramatic change of policy and direction for the council," said Ms Graham.
She said the complexities of the structure and ongoing changes meant people did not fully understand the issues.
If WaterCo fails it will fall back on to the ratepayer, she said.
She is uneasy about the council's ability to interpret and report on its own information. Referring to the HBRC publication Our Place, she said the council's take on the 22 submissions received on the investment company "indicated no strong preference for or against the proposal".
When Hawke's Bay Today reviewed the submissions tabled at the May Strategic Planning and Finance Committee meeting it found 13 of the 22 submissions indicated opposition to the proposal, five supported it with certain conditions, and only two supported it outright.
Most submissions were opposed to the "closed shop" approach, levels of accountability and risk to ratepayers. There are still concerns about the reporting lines, transparency of the process and levels of governance.
Yesterday's regional council meeting agreed to adopt a staged approach for governance of the investment company, initially appointing a seven-person transition board, including the council's chief executive as an ex officio member and chief executive/managing director of the new company. The aim is to have the board set up by next February. The board will also include three councillors and three independent people.
Councillor Neil Kirton said there needed to be strong and multiple voices around the table and while future directors would argue to maximise the bottom line it was important to ensure council and environmental objectives were achieved.
Councillor Liz Remmerswaal thought the process was being rushed through and said it wasn't the best practice to have the HBRC chief executive also sitting on the board.
Ms Graham said: "I don't particularly want to stop it happening, but if it's done I want it to be open and transparent - these assets are owned by the people and their duty is to the people."