Wis. Stat. § 31.11

The department shall issue to every grantee of a permit a certificate evidencing a grant of the permit allowed by law. Every permit, and every franchise heretofore granted by the legislature, to construct, maintain and operate a dam shall become null and void, unless the dam thereby authorized be completed within 5 years from the time when the permit or the franchise was granted; but the department, for good cause, may extend such time for a period not exceeding 2 years.