The board shall subdivide the district into convenient subdistricts not larger than one thousand acres in extent, and prescribe the boundaries thereof within which the sewers and drains necessary to complete the drainage shall be constructed at the expense of the subdistrict when organized, as provided in sections 249.370 to 249.420, but no lands within the boundaries of an incorporated city shall be included in any such subdistrict without the consent of such city expressed by resolution or ordinance of the governing legislative body thereof. When such plans are completed for such subdistricts and filed, the board of trustees may adopt them by resolution, and such resolution, when published in one or more newspapers having a general circulation in the sewer district, shall be binding upon all persons, firms and corporations; and nothing shall be done affecting the drainage and disposition of sewage outside of cities in the district, other than ordinary farm or agricultural drains, inconsistent with such plan, without the permission of the board of trustees as evidenced by the records of proceedings thereof.