Geography of Grant County, South Dakota

Grant County, nestled in the northeastern part of South Dakota, boasts a diverse geographical landscape shaped by its rivers, lakes, plains, and rolling hills. The county’s geography is influenced by the glacial history of the region, which left behind fertile soils and numerous bodies of water. Grant County’s climate is characterized by cold winters, warm summers, and relatively low precipitation, typical of the Great Plains region. In this comprehensive overview, we will explore the geography, climate, rivers, lakes, and other natural features of Grant County, South Dakota.┬áCheck homethodology to learn more about the state of South Dakota.

Geography and Climate:

Grant County covers an area of approximately 688 square miles in the northeastern corner of South Dakota. It is bordered by Roberts County to the north, Codington County to the east, Deuel County to the south, and Day County to the west. The county seat, Milbank, is located near the center of the county.

The landscape of Grant County is primarily composed of gently rolling hills, flat plains, and fertile farmland. The terrain gradually rises from the east to the west, with elevations ranging from around 1,000 feet in the eastern part of the county to over 1,500 feet in the western part. The soil in Grant County is predominantly loamy and well-suited for agriculture, particularly the cultivation of corn, soybeans, wheat, and other cereal grains.

Grant County experiences a continental climate, characterized by cold, snowy winters and warm, relatively dry summers. The region is situated in the transition zone between the humid continental climate of the Midwest and the semi-arid climate of the Great Plains. Average high temperatures in the summer typically range from the mid-70s to low 80s Fahrenheit, while winter highs average in the 20s to 30s Fahrenheit. Precipitation is relatively low throughout the year, with most of the moisture falling as snow in the winter months. The county occasionally experiences severe weather, including thunderstorms, hail, and tornadoes, particularly during the spring and summer months.


Grant County is traversed by several rivers and streams, the most significant of which is the Big Sioux River.

The Big Sioux River flows in a southeasterly direction through the eastern part of Grant County, serving as the county’s border with Minnesota. Originating in Roberts County, the Big Sioux River meanders through the prairies and farmland of eastern South Dakota before joining the Missouri River near Sioux City, Iowa. The river provides important habitat for fish and wildlife and offers recreational opportunities such as fishing, boating, and kayaking.

Other smaller rivers and streams in Grant County include the Whetstone Creek, which flows through the central part of the county, and the Bois de Sioux River, which forms part of the county’s eastern border with Minnesota. These waterways contribute to the county’s hydrology and provide valuable resources for agriculture, wildlife, and recreation.


Grant County is home to several natural and man-made lakes, which add to the county’s scenic beauty and recreational amenities.

Big Stone Lake, located in the northeastern part of the county, is one of the largest natural lakes in South Dakota. Fed by the waters of the Big Sioux River, Big Stone Lake stretches approximately 26 miles along the South Dakota-Minnesota border, offering opportunities for fishing, boating, swimming, and camping.

Artificial reservoirs, such as Lake Farley and Lake Traverse, provide additional recreational opportunities for residents and visitors. Lake Farley, situated near the town of Milbank, features a beach, picnic areas, and walking trails, making it a popular destination for outdoor recreation. Lake Traverse, located in the southeastern part of the county, is part of the chain of lakes along the Minnesota-South Dakota border and offers excellent fishing and boating opportunities.


Grant County, South Dakota, offers a diverse and picturesque landscape characterized by its rivers, lakes, plains, and rolling hills. The county’s fertile soils, abundant water resources, and moderate climate make it an ideal location for agriculture, outdoor recreation, and wildlife habitat. From the meandering waters of the Big Sioux River to the tranquil shores of Big Stone Lake, Grant County’s natural features provide a unique and inviting environment for residents and visitors alike. As stewards of this rich natural heritage, it is essential to preserve and protect the county’s environment for future generations to enjoy.

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