Whenever an application for approval of plans and specifications for a new dam in any stream in this State, or for the enlargement of any dam in any such stream, is filed with the Department of Water Resources, pursuant to Part 1 (commencing with Section 6000) of Division 3 of the Water Code, a copy of such application shall be filed by the applicant with the commission. If then the commission deems that the construction of a fishway over such a dam is necessary for the preservation and protection of fish, and that construction and operation of such fishway is practicable, it shall set a date for a hearing to be held within 90 days after filing of such application with the
commission.
At such hearing the applicant shall be entitled to introduce evidence to show that construction of the fishway is not necessary or is not practicable, taking into consideration the height of the dam and the amount of water available.
If, after the hearing, the commission finds that the construction of the fishway is necessary and practicable it shall, within five days after such hearing, notify the applicant to that effect.
After notice from the commission that a fishway is required, it shall be unlawful to commence the construction of any new dam or the enlargement of any dam without first obtaining the written approval of the commission of the design for such a fishway.