The notice giving a reservoir designation for the first time under section 17 or a notice giving a different designation under section 18 takes effect on the day after the notice is served. Subsection (2) provides that the first reservoir designation for a controlled reservoir being constructed or restored to use takes effect the day after the date of the final certificate in respect of the works. Subsection (3) provides that where a different designation is given after a periodic reassessment for a controlled reservoir being increased or decreased in capacity, the different designation notice takes effect on the day after the date of the final certificate in respect of the works.