Jane Dodds has criticised Dŵr Cymru Welsh Water over the level of pollution in Welsh rivers.
The Mid and West Wales MS said at the Senedd that the company’s chief executive was paid £332,000 in the last financial year.
She said she understands the chief executive and the senior executive team have forgone their bonuses for this year.
But she said it is “galling” to many people, as they pay their water bills, that they see that rivers are more polluted and that little action is taking place.
Ms Dodds said: “We see people in what is called a not-for-profit industry in Wales being paid incredibly high salaries and doing us a favour by not taking their bonuses this year.
“We need radical action. Our rivers remain polluted. People are concerned about the level of our river pollution.”
She asked whether the Welsh Government needs fully devolved powers over water to align legislative competence with national borders so that it can hold Dŵr Cymru Welsh Water to account.
First Minister Mark Drakeford said it was not for him to defend the salary levels of executives in Dŵr Cymru Welsh Water.
He said: “It is for the remuneration committee of Dŵr Cymru itself to take that responsibility.
“The devolution of powers over water is enormously complicated and follows river basins rather than national geographical boundaries.
“I agree with Jane Dodds that the full set of powers that we need in Wales is not yet in our hands, but it isn't a simple matter to put that right.”