41:04:06:05.03Specifications
Section · Administrative Rules of South Dakota · View on sdlegislature.gov ↗
for sign placement and buoy standards for marking losed nonmeandered waters. (1) Signs and buoys must be placed no further apart than 660 feet. (2) Buoys must be a red, spherical design consisting of a diameter not less than 14.5 inches and a length not less than 19.5 inches. (3) Buoys must be marked with contrasting letters at least 3 inches tall stating "CLOSED." (4) All property corner boundaries located in the water must be conspicuously marked with a sign or buoy.
Source: 44 SDR 93, effective December 4, 2017.