"System", "improvement", and "system of improvement", as used in this chapter, shall be held to include a dike, ditch, drain or watercourse, or sewer, and any side, lateral, spur or branch dike, ditch, drain or watercourse, or sewer, or other structure, necessary to secure the object of the improvement. Any number of dikes, ditches, drains or watercourses, or sewers, with their laterals, spurs, and branches with separate outlets, or in the case of sewers with one or more septic tanks, may constitute one system for the protection or reclamation of the land included in any district. But no system shall be established or constructed unless sufficient outlet or outlets, or in the case of sewers, sufficient septic tank or tanks, are provided for any drainage or sewerage of such district. Such outlet or outlets, or septic tank or tanks, may be either within or without the boundaries of the improvement district hereinafter provided for. Any natural watercourse may be improved in accordance with the provisions of this chapter.
"Damages", as used in this chapter, shall be held to include the value of the property taken and injury to property not taken, or either, as the case may be. "Property benefited" and "property damaged", as used in this chapter, shall be held to include land, platted or unplatted, whether subject to or exempt from general taxation, and roads other than public roads. "Public roads", as used in this chapter, shall be held to include state and county roads, streets, alleys and other public places; and "other roads", as used in this chapter shall be held to include railroads, street railroads, interurban railroads, logging roads, tramways and private roads and the right-of-way, roadbeds and tracks thereof.
"Public utilities", as used in this chapter, shall be held to include irrigation, power and other canals, flumes, conduits and ditches, telegraph, telephone and electric transmission and pole lines, and oil, gas and other pipe lines. "County engineer", as used in this chapter, shall be held to include any engineer specially employed by the board of county commissioners or the board of supervisors to report upon and prepare plans for or to superintend the construction of a system or the maintenance thereof under the provisions of this chapter. "Prosecuting attorney", as used in this chapter, shall be held to include any attorney specially employed by the board of county commissioners in connection with the carrying out of the provisions of this chapter to advise or carry on proceedings in court with reference to a system of improvement initiated and constructed under the provisions of this chapter.