The Treasury Department is the depository for county agencies, school districts, and special district funds.  All banking functions are handled in Treasury, which is in all respects the equivalent of a small business bank processing $13.5 billion annually.  The Treasurer selects the official county bank to be the custodian of those funds.

Most county agencies and most school districts are required to deposit their funds in the Treasury and all the funds received by the Collections Department are placed in the Treasury.  The Treasury monitors balances, deposits, and transfers.  The Treasury approves payment methods, participates in bond issuances by the County and by school districts, provides a cash window for public needs, and manages the vault spaces used by other county agencies.