Minn. Stat. § 103G.216
For the purposes of this section and section 103G.2165, "fish kill" means an incident resulting in the death of 25 or more fish within one linear mile of a flowing water or 25 or more fish within a square mile of a nonflowing water, excluding fish lawfully taken under the game and fish laws.
A state or county staff person or official who learns of a fish kill in public waters must report the location of the fish kill to the Minnesota state duty officer within one hour of being notified of a fish kill or within four hours of first observing the fish kill. The Minnesota state duty officer must alert the Departments of Agriculture, Health, and Natural Resources and the Pollution Control Agency of the location of the fish kill within one hour of being notified of the fish kill. When a fish kill is reported, it must be posted to the EQB Monitor in the next scheduled posting.
Minn. Stat. § 103G.216