Queenstown Lakes Mayor Vanessa van Uden said property developer Mike Coburn and planning consultant and former council district planner Jeffery Brown would replace the men on the board of the council-controlled organisation.
Mr Hill retired by rotation in March and did not seek re-election, while Mr Bickers resigned.
Ms van Uden said it was a "challenging environment" and the two new directors brought "important and varied skill sets and perspective".
Mr Coburn brought to the table a strong understanding of the development process and the regulatory interface, while Mr Brown brought extensive resource management knowledge from throughout New Zealand.
"I think these appointments will be of huge benefit to the company.
"I'd like to acknowledge that both Jeff and Mike are acutely aware of any potential or perceived conflict of interest that these appointments might raise, but both relish the opportunity this presents for the wider community.
"I am confident they will add significant value to the board," Ms van Uden said.
Appointing two directors, who both had intimate knowledge and first-hand experience of the business carried out by the company, was flagging the council was "genuine in its commitment to ensuring Lakes Environmental continued to work towards delivering enhanced services".
Chairwoman Anne Urlwin has also been appointed for further four-year term.
