Elliot Mainzer has been appointed the new president and CEO of the California Independent System Operator(ISO), the agency announced on Thursday.

Mainzer, who is currently serving as administrator and CEO of Portland, OR-based Bonneville Power Administration will replace Steve Berberich who is retiring at the end of September.

“Elliot’s demonstrated success leading a large, complex power and transmission organization will serve CAISO, our customers and stakeholders well,” said the CAISO Board of Governors said in the announcement. “We are happy to have a leader so knowledgeable about integrating renewables and passionate about building on CAISO’s organizational strengths and momentum toward low-carbon electricity.”

Berberich has been with California ISO for the past fourteen years, serving as CEO for nine years.