The simple answer is that a watershed contains all the land and water features that drain excess surface water to a specific location on the landscape. In other words, standing on the land and looking around, everything uphill from that position routes water to that point and falls within its watershed.
The definition of a watershed is scale and scope independent. For example, a small pothole wetland surrounded by an immediate divide will receive limited overland flow. Some wetland watersheds may only be a few acres in size.
In contrast, a lake like Lake Pepin, on the Minnesota-Wisconsin border, drains much of Minnesota including all the land that drains to the Upper Mississippi, St. Croix, and Minnesota Rivers. Its watershed is more than 30 million acres.
Both of these meet the same definition of a watershed. The only difference is the amount of land that contributes overland flow to the selected point of interest.
The Otter Tail River Watershed (OTRW), like the whole of Minnesota, boasts a diverse landscape. Three ecoregions create this diversity: forests populate the north, lakes both large and small populate the heart of the watershed, and the fertile prairie farmlands of the Red River Valley stretch into the southwest corner of the watershed. Two important rivers—the Otter Tail River and Pelican River—originate in the watershed and later join together with the Bois de Sioux River to become the Red River of the North. People also shape the diverse landscape and include the White Earth Nation; the cities of Detroit Lakes, Fergus Falls, Pelican Rapids, Perham, and Ottertail; and residents who live or vacation on the shorelines of the watershed’s many lakes.
The OTRW watershed is brimming with water above and below the surface. This includes 996 lakes (40 of which are over 1,000 acres in surface area), 975 miles of streams, and both deep and shallow aquifers. In fact, 30% of the watershed is covered by surface water, resulting in 4,210 miles of lake and stream shoreline.
The watershed covers 1,104,323 acres (1,725 square miles), the majority of which are in Becker (31%) and Otter Tail (68%) counties. Small portions of the watershed (<1%) are also located in Clearwater, Wilkin, and Clay counties.
The Pomme de Terre River watershed is located in west central Minnesota. The two largest cities in the watershed are Morris and Appleton. The watershed covers approximately 874 square miles (559,968 acres) of which 74% of the land is used for cropland and pasture. The watershed drains through the Pomme de Terre River, before discharging into the Minnesota River below Marsh Lake. At its headwaters in Ottertail County, the watershed is dominated by lakes and hardwood forests. As the Pomme de Terre River flows south, the landscape transitions to mostly cropland. Within the Minnesota River basin, the Pomme de Terre watershed has some of the best water quality. However, there is still need for improvement as many stream segments and lakes are impaired for aquatic life, recreation, and consumption
Over the millennia, water has been a driving force in forming the Buffalo-Red River Watershed (BRRW) planning area. From the ice age ending just 10,000 years ago to extensive drainage ditching beginning in the early 20th century, there is no doubt water has always played a major role in this area. Historically in the BRRW, and more broadly around the world, water management has occurred along political boundaries. However, water adheres to a different set of rules, namely gravity, flowing along the path of least resistance from high to low elevations. This comprehensive watershed management plan represents a paradigm change in water management across the state of Minnesota and in the BRRW: to base water management on a watershed rather than a political scale.
Over 12,000 years ago, much of the BRRW was covered by the massive Glacial Lake Agassiz. This lake existed for around 4,000 years until the retreat of the glaciers further north into Canada, which allowed the lake to drain north. What remains today in watersheds within the Red River Basin are areas of the lake bottom, a series of beach ridges, and moraine areas. This glacial lake plain contains much of the western extent of the BRRW. The fertile, yet poorly drained soils provide a setting rich for agricultural production. Much of the historic wetlands have been drained through extensive ditching and prairie converted to farmland. Despite being a productive landscape, the low relief—coupled with an ever so slight downward tilt to the north—is prone to destructive overland flooding.
The Bois de Sioux River rises from the outlet of Lake Traverse, on the MN/SD border. It drains an area of over 1,970 square miles - spanning 3 states - and forms the headwaters of the Red River of the North at its confluence with the Otter Tail River in Breckenridge, MN/Wahpeton, ND.
Major Minnesota tributaries to the Bois de Sioux include the Mustinka and Rabbit Rivers. In total, around 93% of the watershed's land is used for agricultural production.
The Mustinka River begins in southwest Otter Tail County and passes through portions of Grant and Traverse Counties on its 68-mile path to Lake Traverse. Water from Lake Traverse forms the headwaters of the Bois de Sioux River at its outlet, which in turn forms the Red River of the North at its confluence with the Otter Tail River at Breckenridge. The Mustinka's watershed encompasses 909 square miles, approximately 46% of the overall Bois de Sioux River watershed's drainage area.
The Rabbit River rises from wetlands near Western, Minnesota to flow 32 miles to its outlet at the Bois de Sioux River, 8 miles west of Campbell, MN. The watershed drains an area of just over 320 square miles, which composes approximately 16% of the overall Bois de Sioux River watershed's drainage area.
The Chippewa River Watershed is located in the west-central portion of Minnesota. The 2083.6 square mile watershed is agriculturally dominated. The area is primarily agricultural with 79 percent of the land used for cropland and pasture. The majority of the cropland is planted with corn and soybeans. The watershed is located in the North Central Hardwood Forest Ecoregion, Northern Glaciated Plains Ecoregion, and the Western Corn Belt Plains Ecoregion (Figure 4). The Chippewa River and its tributaries flow through eight counties where it combines with the Minnesota River in the town of Montevideo; however, there is a water diversion channel near the town of Watson where water is diverted west to the Minnesota River to lessen the flooding in Montevideo. Montevideo, Benson, Starbuck, and Glenwood are the largest towns in the watershed, but the watershed is mostly rural, with developed areas making up only five percent of the land use
The Long Prairie River watershed covers approximately 551,612 acres (862 miles) and is located in the central part of the Upper Mississippi River Basin in central Minnesota. The watershed encompasses all or parts of Douglas, Otter Tail, Todd, Morrison, and Wadena counties. The Long Prairie River watershed includes more than 240 lakes greater than 10 acres in size and 884 miles of rivers and streams. The Long Prairie begins in Douglas County and flows through Todd and Morrison counties before entering the Crow Wing River south of Motley.