The hidden parks money has already prompted a review of 560 special state funds by the Department of Finance and a separate investigation into the parks department itself.
The Attorney General is also looking into the scandal. But lawmakers say that's not enough. Many Republican lawmakers say a broader review is needed to look for other hidden pots of cash.
The audit is expected to take seven months, but State Auditor Elaine Howle said her office would be able to deliver its findings related to the hidden funds by January.
The Associated Press contributed to this report.