From this story on yankton.net:
In the wake of soaring deer deaths, the South Dakota Game, Fish and Parks Department has removed all unsold licenses from deer hunting units in six area counties. Secretary Jeff Vonk took the action after receiving authority from the GF&P Commission last week. The action affects Bon Homme, Hutchinson, Yankton, Clay, Union and Charles Mix counties. Yankton County conservation officer Sam Schelhaas has seen and heard firsthand the number of deer deaths across southeast South Dakota. The outbreak has worsened over the past month, with most cases attributed to Epizootic Hemorrhagic Disease (EHD) or a similar disease known as bluetongue.