OUR WATERSHED
History
Two million years ago, glaciers polished and flattened eastern South Dakota, creating the Big Sioux River watershed. By the 13th century, Santee and Yankton Sioux tribes settled along the river, attracted by the fertile farmland and wild game. The Sioux began to encounter French trappers in the 16th century. Many French fur trappers hunted the Big Sioux River while using it for northward travel. After the Louisiana Purchase of 1803, Americans began exploring Dakota Territory, including the Lewis & Clark expedition and Captain James Allen, who documented their encounters with the majestic Big Sioux.
Just as the land had appealed to the Santee and Yankton tribes, the rich soil and abundant wildlife attracted settlers to Dakota Territory. The Homestead Act of 1862 encouraged westward movement and agricultural development. White settlement led to violent conflicts and the eventual displacement of the Sioux. In 1875, Congress granted homesteading rights to Native people, and the Flandreau (Santee) Indians banded together to acquire titles for farmland as a guard against losing their land. Today, the Big Sioux cuts through the heart of the Flandreau Indian Reservation.
As the homesteaders developed the Big Sioux region, they introduced livestock and large-scale farming techniques. The early twentieth century bore witness to a boom in agriculture in the state of South Dakota. The over-tillage of soil and loss of native prairie grasses ushered the state into the Dustbowl Era. After conservation efforts by the CCC and the economic boost associated with World War II, South Dakota once again prospered. The Big Sioux Region of Eastern South Dakota has continued to develop, still boasting a proud rural, agricultural tradition while growing urban cities like Sioux Falls and Brookings.
Big Sioux River Watershed
Beginning as a small stream near Summit, South Dakota, the Big Sioux River rises on a low plateau known as the Coteau des Prairies. As the river winds through Eastern South Dakota, it grows in size and intensity, eventually flowing over the waterfall at Falls Park in Sioux Falls. The river continues on, flowing through bountiful farmland, rural communities, and state parks teeming with flora and fauna. After flowing for 419 miles, the Big Sioux River empties into the Missouri River at Sioux City, Iowa.
The scope of a river extends beyond its banks and includes all the communities whose excess water sheds to that river. Though a town may not sit directly on the Big Sioux River, it can still impact the health of the water. Those communities constitute a watershed district.
Many streams, lakes, and rivers feed into the Big Sioux River from portions of South Dakota, Minnesota, and Iowa. Together, these water bodies form the Big Sioux River watershed, draining roughly 9,000 square miles, an area larger than New Jersey. Today, 40% of South Dakota's population lives in the watershed.
Rivers and Streams of the Watershed
Photos of each river and stream segment coming in 2025! Click here to learn about the 12 water quality parameters tested for in the Big Sioux River watershed by the South Dakota Department of Agriculture and Natural Resources and partner organizations.
Lakes of the Watershed
Photos of each lake coming in 2025! Click here to learn about the 12 water quality parameters tested for in the Big Sioux River watershed by the South Dakota Department of Agriculture and Natural Resources and partner organizations.
Beneficial Uses
The Environmental Protection Agency requires all states to specify goals and expectations for how each water body is used. Based on these requirements, the South Dakota Department of Agriculture and Natural Resources (DANR) has designated all surface waters in the state for one or more of 11 beneficial uses.
A water body is considered impaired (non-supporting) if it does not meet its beneficial use standard(s). When a water body is considered impaired, a Total Maximum Daily Load (TMDL) must be developed. A TMDL is the amount of pollution a water body can receive and still support its designated beneficial uses. The TMDL should specify quantifiable targets and associated actions that will allow the water body to support its designated beneficial uses.
Scroll down to learn more about the 11 beneficial uses for surface waters in South Dakota!
Domestic Water Supply Waters
What does this mean?
Surface waters that are suitable for human consumption, culinary or food processing purposes, and other household purposes after suitable conventional treatment.
What does this mean?
Surface waters are capable of supporting aquatic life and are suitable for supporting a permanent population of coldwater fish from natural reproduction or fingerling stocking. Warmwater fish may also be present.
Coldwater Permanent Fish Life Propagation Waters
Coldwater Marginal Fish Life Propagation Waters
What does this mean?
Surface waters are capable of supporting aquatic life and are suitable for stocked catchable-size coldwater fish during portions of the year. However, because of critical natural conditions including low flows, siltation, or warm temperatures, the waters are not suitable for permanent coldwater fish population. Warmwater fish may also be present.
What does this mean?
Surface waters are capable of supporting aquatic life and are suitable for the propagation or maintenance, or both, of warmwater fish but which may suffer occasional fish kills because of critical natural conditions.
Warmwater Permanent Fish Life Propagation Waters
What does this mean?
Surface waters are capable of supporting aquatic life and are suitable for the permanent propagation or maintenance, or both, of warmwater fish.
Warmwater Semipermanent Fish Life Propagation Waters
What does this mean?
Surface waters will support aquatic life, particularly more tolerant species of warmwater fish. Aquatic life will be supported naturally or by frequent stocking and intensive management. However, they will suffer frequent fish kills because of critical natural conditions.
Warmwater Marginal Fish Life Propagation Waters
Immersion Recreation Waters
What does this mean?
Surface waters that are suitable for uses where the human body may come in direct contact with the water, to the point of complete submersion, and where water may be accidentally ingested or where certain sensitive organs such as the eyes, ears, and nose may be exposed to water.
Limited Contact Recreation Waters
What does this mean?
Surface waters that are suitable for boating, fishing, and other water-related recreation, other than immersion recreation, where a person's water contact is limited to the extent that infections of the eyes, ears, respiratory or digestive systems, or urogenital areas are normally avoided.
What does this mean?
Surface waters that are suitable for irrigating farm lands, ranch lands, gardens, and recreational areas.
Irrigation Waters
Commerce and Industry Waters
What does this mean?
Surface waters that are suitable for use as cooling water, industrial process water, navigation, and production of hydroelectric power.
What does this mean?
A beneficial use classification assigned to all surface waters of the state that: (a) May support recreation, in and on the water, and fish and aquatic life, when sufficient quantities of water are present for sufficient duration to support those uses; (b) Provide habitat for aquatic and semiaquatic wild animals and fowl; (c) Provide natural food chain maintenance; and (d) Are of suitable quality for watering domestic and wild animals.