Many lakes in South Dakota’s Prairie Pothole Region are expanding. Lake Thompson in eastern South Dakota is one that has displayed remarkable change in recent decades.
An aerial image from 1952 shows it as a wetland, with a small area of open water. Landsat began observing the area with near-infrared imaging in 1972. By the mid-1980s, the low land filled with enough water to become South Dakota’s largest natural lake. There have been some fluctuations in lake levels since then, and some shoreline and shallow areas changed between dryland, marshland, and open water.
Wildlife responds to the lake’s changes. Herons and egrets use the shallow water and mudflats on the lake’s fringes. Pelicans, gulls, terns, and ducks thrive in the open water.
The dead trees that remained standing were perfect habitat for cormorants, eagles, and herons. Eventually, the dead trees collapsed, and the habitat changed again.
Landsat data can be used to map these changes and help managers understand the interaction between lake levels and wildlife populations.