Upon the Governor issuing such proclamation as is provided for in Section 17-11-17, the governing body of the district, as constituted in this chapter, shall meet and adopt an annual budget for the operation, maintenance and support of the district. The funds for the administrative support of the district shall be apportioned equally on an annual basis of not more than Fifty Cents (50¢) per capita of the population of each associated member of the district, according to the last official federal census. If a city associated with the district is within a county which is also associated with the district, the city and county shall each pay not more than Twenty-five Cents (25¢) for the residents of such city. Such amount may be paid by each associated member from its general or surplus funds on or before April 1st of each calendar year. The governing body of the district may from time to time revise or amend the budget of the district.