The leader of Philadelphia's most powerful locally focused foundation is stepping down.

Jeremy Nowak and the board of the William Penn Foundation announced Wednesday that it was time they go their separate ways. (Disclosure: WHYY has received grants from the William Penn Foundation.)

Fresh on the heels of announcing a new strategic plan, the foundation says Nowak had a different vision for realizing its key objectives.

Helen Davis Picher will now serve as interim president. She was not involved in the shared decision that Nowak step down.

"As the implementation of the plan was going forward, the foundation and Mr. Nowak had some differences in the approach regarding the implementation of the plan," Picher said. "Therefore there was an agreement that it was time for a change in leadership."

Nowak, who took the helm of the $2 billion foundation only a year and a half ago, had become a source of controversy.

High-profile support last summer of what's seen as a pro-charter school organization had drawn criticism in public education circles.

David Fair, who runs a consulting firm for local nonprofits, says Nowak's leadership style may have grown at odds with the foundation, which is largely controlled by the Haas family.

Still, Fair says, the main impact of Nowak's departure will be uncertainty rippling across the region's philanthropic ecosystem.

"What is the foundation really going to be doing with its money?" Fair said. "And how is it going to be making the decisions about what is worthy of a William Penn Foundation investment?

"When it finally makes those decisions, that will impact the decisions of almost every other foundation in the community."

The William Penn Foundation issues about $80 million in grants every year. It recently introduced a refined grant-making focus on education, local watersheds and cultural organizations.

The foundation's interim director says Nowak's departure will not change the principles of its new strategic plan, only their implementation.

In a statement, Nowak said, "I am extraordinarily proud of the work we have done that will guide the William Penn Foundation for years to come."