74:02:08:07.01Category 3 spillway
Section · Administrative Rules of South Dakota · View on sdlegislature.gov ↗
design flood exception. For small size category 3 dams with an emergency spillway, the minimum spillway design flood is a 25-year frequency if the product of the intermediate storage capacity times the effective height is less than 3000. For small size category 3 dams without an emergency spillway, the spillway design flood is a 25-year frequency if the product of the maximum storage capacity times the effective height is less than 3000.
Source: 13 SDR 197, effective July 2, 1987.