Great Oasis Lake at 1,466 acres (593 ha) was once second-largest but was drained in the early 20th century for farmland.

[4] Lake Shetek has long harbored a robust population of rough fish, native but economically undesirable.

[1] Due to its shallowness, the entire basin constitutes the littoral zone, which harbors common invertebrates like snails and insect larvae.

[2] Five common species of waterfowl all breed on Lake Shetek: the American coot, gadwall, mallard, northern shoveler, and ruddy duck.

He noted that the region's Dakota people called the lake Rabechy, meaning "place where pelicans nest."

[7] However the Dakota War of 1862 broke out and 15 settlers were killed and a dozen taken captive at Slaughter Slough.

[2] This initial tourist economy peaked in the Roaring Twenties and subsided with Valhalla Pavilion burning down in 1928 and the onset of the Great Depression.

[7] To combat unemployment during the Depression, the federal government authorized several job creation programs to conduct public work projects.

The Works Progress Administration (WPA) arrived in 1934 with an ambitious plan to build a road system across Lake Shetek and a state park on the wooded eastern shore.

Although the shoreline was greatly developed, better runoff management practices throughout the watershed improved Shetek's water quality.

[2] Surface runoff from farms and lawns threatens to carry in excessive nutrients that can cause algal blooms.