Opposition to the Government's proposed partial sale of state-owned assets was unanimous at the only select committee hearing to be held in the South Island.
Parliament's finance and expenditure select committee met in Christchurch on Monday.
It is considering legislation allowing the Government to sell up to 49% of Genesis Energy, Meridian Energy, Mighty River Power and Solid Energy.
Submitter Bronwyn Judge told the hearing companies that use the Waitaki River to generate power will care less about environmental damage if private investors are allowed.
"I don't think it is appropriate for assets such as energy corporations to look after our rivers, when their primary objective is profit.
"And we certainly shouldn't be selling these assets off to shareholders who care even less."
However, committee member and National MP Nick Smith said there is no scientific evidence to back up that claim.
Several other submissions outlined the success of the companies in their current state and questioned whether it was worth reducing how much they can earn the Government in exchange for quick cash from their partial sales.
The final public hearing will be held at Parliament on Wednesday.