Williamson has faced allegations of overspending before. In 2009, records show he spent $500 on a hotel room and took officials out to dinner for $450.
The audit holds the board of trustees responsible and blames board members for a lack of accountability and fostering a culture of inappropriate spending.
Tulsa city councilor Karen Gilbert calls the findings shocking.
"You just can't have lavish spending. When you're dealing with taxpayer dollars. So we've got to get to the root of it. And find out why this happened, and make sure that it doesn't happen again," Gilbert said.
The audit recommends EMSA improve its financial oversight by performing evaluations of its CEO and other employees.
EMSA board members will discuss the findings of the audit during a meeting Wednesday afternoon. In the meantime, EMSA released this statement:
"The audit, released this afternoon, was requested by the EMSA board, as part of our efforts in past months to improve the organization's overall practices and policies," said Lillian Perryman, chairwoman of the EMSA board.
"We requested it because we wanted specific areas evaluated by a third party and look forward to seeing their recommendations. We are still reviewing the report and it will be discussed in detail in tomorrow's board meeting.
"The board and EMSA management must review the report and recommendations made by the State Auditor in detail and make decisions based on what is best for the citizens of the communities served by EMSA. What we do with the information is the critical piece of the audit process and we will be committed to improving organizational practices. The quality of care delivered by our service to our citizens in the Tulsa and Oklahoma City areas is excellent and has never been called into question.
"Any recommendations will be evaluated and acted upon rapidly in the next few months, as appropriate. All of this discussion will happen in open, public meetings at board and committee meetings."