While most of the land on which Fort Stevenson State Park now sits was used for agriculture, sections of native mixed grass prairie still remain and have been enhanced with plantings of native grasses and prairie species. Common native plants found here are little bluestem, blue grama, needle-and-thread and western wheatgrass, along with purple coneflower, fringed sage, lead plant and prairie smoke. An arboretum containing over 50 native and non-native trees, shrubs, wildflowers and grasses has been established near the campgrounds.
Two rare animal species, the piping plover and the black-tailed prairie dog, can be found within the park. The colony of black-tailed prairie dogs was re-introduced in the 1970s. One of four species of prairie dogs found in the U.S., the black-tailed prairie dog is considered a cornerstone species in the prairie ecosystem, providing food or burrows for a range of other species, including mountain plovers, burrowing owls, badgers, swift foxes and black-footed ferrets.
Piping plovers can be sighted along the shoreline. This federally protected shorebird nests along alkali lakes, reservoir shorelines and river sandbars in the spring, after wintering on the Gulf Coast in the southeastern U.S.
During periods of low water, petrified wood, seams of lignite coal, leaf and marine fossils can be seen in the steep cutbank along the shore. Collecting any natural, historic or cultural artifact on state park land is prohibited by state statute or administrative rule.
Like all public recreation areas on Lake Sakakawea, the major attractions for visitors are fishing and water sports. Anglers will find over 35 species of fish, including trophy-size walleye, northern pike, Chinook salmon, small-mouth bass and brown and rainbow trout, as well as catfish and yellow perch.