The park's three campgrounds give visitors a variety of recreational opportunities, from boating to hiking to disc golf. The Corps of Engineers began building the Oahe Dam in 1948 and in 1962 started generating electricity. It's one of the largest constructed reservoirs in the United States, measuring 231 miles connecting the capital cities of South Dakota and North Dakota.

Oahe Downstream is one of the South Dakota state parks that offers the opportunity for visitors to see the majestic bald eagle. During winter, bird watchers can view eagles that roost in the treetops below the dam. They typically can be viewed perching within 50 feet of the riverbank in tall cottonwood trees.

Everyone is encouraged to visit the interactive South Dakota prairie butterfly garden located near the main entrance at Oahe Downstream. Find 17 species of native prairie plants, identify some of common butterflies, and learn something new about butterflies of South Dakota.