The changes at the top of CAISO’s executive ladder that began last month with the installation of CEO Elliot Mainzer continued this week, as the ISO announced a new chief operating officer and the retirement of two veteran vice presidents.

Mark Rothleder, who has been with CAISO since its founding in 1997, will take the newly created No. 2 position as COO under Mainzer, who replaced Steve Berberich. (See CAISO Retiring, Incoming CEOs Field Questions.)

Rothleder currently serves as the ISO’s vice president of market policy and performance, a job in which he warned of potential summer shortfalls long before they occurred in August and September as California shifted from its reliance on natural gas to wind and solar. (See CAISO, CPUC Warn of ‘Reliability Emergency’.) Previously, a suite of vice presidents, including Rothleder, reported directly to the CEO.

Mainzer said in a news release that he looks forward to teaming up with Rothleder to “meet the company’s strategic goal of enabling a reliable transition to a clean energy grid.”

“Mark has been with the ISO since its inception, giving him immense and deep knowledge of our organization and the industry,” Mainzer said in the statement. “I know Mark will do an outstanding job in his new role as COO.”

Rothleder is the ISO’s longest-serving employee and previously held positions as executive director of market analysis and development, principal market developer and director of market operations.

“Since joining the ISO 23 years ago, Rothleder has worked extensively on implementing and integrating the approved market rules for California’s competitive wholesale energy and reserves markets,” the ISO said.

CAISO also said that Petar Ristanovic, vice president of technology, and Eric Schmitt, vice president of operations, are retiring at the end of the year.

Ristanovic, who has more than 35 years of experience in the electric industry, came to CAISO from Siemens Energy Automation, where he served as global innovation manager. Previously he worked at the University of Belgrade’s Nikola Tesla Institute of Electrical Engineering, developing and implementing advanced power system applications.

Schmitt, who also has more than 35 years of experience, oversees California’s bulk electric system operations, real-time engineering and market services. Before joining the ISO in 2011, he served as senior vice president at Science Applications International Corp. in Tysons, Va.

“Petar and Eric represent the gold standard in the energy industry, and both were instrumental in shaping the California ISO into the pioneering, modern power grid and electricity market of today,” Mainzer said.

CAISO has not announced plans to replace them and did not respond to an inquiry by press time.