As used in this chapter, unless the context otherwise requires:
(1) “Interstate watershed project” means any undertaking in cooperation with the federal government for preparing and carrying out works of improvement for the control and prevention of floodwater, erosion, and sediment damage, and the conservation, development, utilization, and disposal of water lying wholly or in part outside the boundaries of this state, the installation of which will benefit lands and property in this state;
(2) “Improvement district” or “district” includes drainage, soil or water conservation, irrigation, levee, flood control, or other special improvement district, and all other political subdivisions including incorporated cities and towns;
(3) “Bonds” means any notes, bonds, or other obligations without regard to form or source of payment, issued by any district pursuant to any law of this state;
(4) “Taxes” means general taxes levied on an ad valorem basis or special benefit taxes levied pursuant to the laws governing improvement districts.