 Manyaska is a name of Sioux Indian origin.According to the United States Census Bureau, the township has a total area of 34.4 square miles (89.1 km²), of which 33.8 square miles (87.6 km²) of it is land and 0.6 square miles (1.5 km²) of it (1.63%) is water.As of the census of 2000, there were 337 people, 129 households, and 101 families residing in the township.