In each county of the State of Mississippi which is a part of the Pat Harrison Waterway District, so long as funds are found to be necessary for the operation of the district by annual legislative approval of the district budget, the tax collector of such county shall pay into the depository selected by the water district for such purpose an amount to be determined as follows: each county shall pay a pro rata share (not to exceed the avails of one (1) mill through September 30, 1997, and not to exceed the avails of three-fourths (¾) mill through September 30, 2005, and not to exceed seven-eighths (⅞) mill thereafter) of the annual district budget based on the proportion that the most recent total assessed valuation of the county bears to the most recent aggregate total assessed valuation of all the counties which comprise the district; provided, however, that any county bordering on the Gulf of Mexico which by action of the board of supervisors has created and authorized a port authority and which has been paying into the port authority the avails of a two-mill levy that was established under Section 27-39-3 shall pay an amount not to exceed one-tenth (1/1) mill through September 30, 2005, and not to exceed two-tenths (2/1) mill thereafter, of the total assessed valuation of the county to the Pat Harrison Waterway District pursuant to this section and the assessed valuation of that county shall not be considered when calculating each county’s pro rata share of the district’s budget. Of the amount paid by counties required to pay to the district an amount not to exceed seven-eighths (⅞) mill, an amount equivalent to the avails of one-eighth (⅛) mill shall be utilized to fund flood control, water management and other similar projects as requested by counties in the district. Of the amount paid by counties required to pay to the district an amount not to exceed two-tenths (2/1) mill, an amount equivalent to the avails of one-tenth (1/1) mill shall be utilized to fund flood control, water management and other similar projects as requested by counties in the district. It shall be the duty of the Pat Harrison Waterway District Board of Directors in the month of November annually upon receipt of the total assessed valuation of the member counties, certified by the Department of Revenue, to prepare a request to the board of supervisors of member counties to levy a tax using the formula herein established not to exceed the maximum number of mills authorized by this section. Member counties shall remit their share of the district budget no later than March 1 of each year.