(a) Promptly after a petition is filed under § 11.304 of this Code, the commission shall consider whether the adjudication would be in the public interest. If the commission finds that an adjudication would be in the public interest, it shall enter an order to that effect, designating the stream or segment to be adjudicated. The executive director shall have an investigation made of the area involved in order to gather relevant data and information essential to the proper understanding of the claims of water rights involved. The results of the investigation shall be reduced to writing and made a matter of record in the commission office.
(b) In connection with the investigation, the executive director shall have a map or plat made showing with substantial accuracy the course of the stream or segment and the location of reservoirs, diversion works, and places of use, including lands which are being irrigated or have facilities for irrigation.