The board may: (1) Make initial determination that the district's facilities furnish benefit to improvements upon land as well as land alone within the district in protecting against and furnishing runoff for surface and/or flood waters; (2) make initial determination that lands and improvements thereon outside of the territorial limits of the district are receiving a service from the facilities of the district, and are benefited thereby in that waters from such lands through ditches, drains, or other artificial methods, other than by natural flow or seepage, are so cast as to have outlet through the district's facilities; (3) determine that properties so found to be served should pay a just proportion of the operational and maintenance costs of the district; (4) in connection with so finding, cause a roll of property thus served and benefited by the district's facilities to be prepared and filed with it, and give notice of a hearing thereon as provided in this chapter; (5) hold public hearings to determine the ultimate facts and approve an ultimate roll of properties served and benefited by the facilities of the district and valuations thereof to serve as a basis against which annual dollar rate levy may be assessed for continuous benefits furnished such properties; make revision thereof as the facts warrant from time to time; provide for the levying of such dollar rate levy; and make return of such roll finally adopted by certifying and filing a copy thereof with the auditor, assessor and treasurer of the county wherein the properties involved are located.