The street fund may be from time to time further enhanced or increased from any moneys available therefor on orders made by the City Council. No money shall be withdrawn from the fund, except that the same shall be for a proper street purpose in payment of expenditures for construction, alteration, repair, improvement and maintenance of City streets or materials or equipment purchased therefor. [Code 1970 § 3.72.040; Code 1954 § 2-16.16.]