1. A river regulating district formed and established under the provisions of title 21 of this article may be given extended powers and duties by the formation by the department of a river improvement or drainage improvement district, or both, which districts shall have the same boundaries as the river regulating district, shall be joined with it as one body corporate and subject to the general supervision of the department and shall be administered by the board of the river regulating district. If this is done, the board shall thenceforth exercise the powers of the department as set forth in title 19 and title 23 of this article, except those under sections 15-1945 and 15-1957 and as otherwise provided below. Whenever the department is empowered to set up districts under title 19 and title 23 of this article, the board may, by the same procedure, set up river or drainage improvement sub-districts which shall not be separate bodies corporate but shall be financial and assessment entities and each of which shall have an association. Any function which title 19 and title 23 specify to be performed by the Department of Transportation or the Commissioner thereof shall be performed by the board through its engineering forces, and legal matters may be handled by counsel to the board. Whenever the statute requires the board to file in final form orders, statements, schedules, reports, plans, or other papers, to give notice of such filing and, after review, if any, to record or file the same such papers may not be filed except with the consent and approval of the department. All contract plans and specifications must similarly receive such approval to make them valid. All contracts must be so approved before they are signed and all acts authorizing the borrowing of money, making of assessments, or statements of the amounts which must be collected with annual taxes, must be approved by the department before they are submitted to the Comptroller. In proper cases, any such district may be assessed as an entity for benefits derived from the operation of another sub-district or the construction of a regulating reservoir.

2. Proceedings for the formation of a joint district shall be as nearly as may be those set forth in title 19 or title 23 as the case may be. They shall be initiated by a written petition filed with the department. On receipt thereof the department shall make such investigation as it deems necessary, shall set the time and place for a hearing thereon and shall give notice of the same by publication pursuant to the provisions of subdivision 1 of section 15-0903. At the hearing, the department will hear the applicants and the board, and such objectors as have filed written objections. After the hearing the department shall approve, modify and approve or reject the application according to what it finds to be the best interest of the people of the state. The action of the department shall be in the form of a signed written order, copies of which shall be filed in the offices of the clerk of each county, town, city or village, any part of which lies within the proposed district. Notice of such filing shall be given by publication and the acts of the department may be reviewed provided such review is initiated within sixty days of the date of the order. If not reviewed or if confirmed by the courts reviewing the matter, the order shall be recorded in the offices of the clerks of the various counties; thereupon the order shall become final and the joint district shall be deemed to have been formed on the date of the order. Certified copies of such order shall be served on the board and shall be its authority to act for the new district.