Willow Lake is a city in Clark County, South Dakota, United States.

[7] According to the United States Census Bureau, the city has a total area of 0.37 square miles (0.96 km2), all land.

37.4% of all households were made up of individuals, and 23.5% had someone living alone who was 65 years of age or older.

The racial makeup of the city was 93.88% White, 5.10% Native American, and 1.02% from two or more races.

37.3% of all households were made up of individuals, and 23.0% had someone living alone who was 65 years of age or older.

About 13.6% of families and 20.1% of the population were below the poverty line, including 29.3% of those under the age of eighteen and 20.3% of those 65 or over.