(a) A county in which a district is located may pay:
(1) part of the principal or redemption price of or interest on the district's bonds; or
(2) the cost of operating or maintaining the district's toll road project.
(b) The county may establish or maintain a reserve fund or a depreciation and replacement fund for the district's bonds or toll road project as a supplement to the district's pledge of revenue for those purposes or instead of a pledge of the district's revenue or taxes.