North Sterling State Park features a 3,000 surface-acre reservoir lying on the South Platte Terrace of the western Great Plains at 4,060 feet in elevation. The water from the reservoir and its drainages supports a greater abundance of plant and animal species than normally found in a short grass prairie ecosystem.
The major plant communities at the park are remnants of short grass prairie, rehabilitated farmland and wetland and riparian communities. Short-grass prairie, including blue grama, western wheatgrass, needle-and-thread grass, buffalograss and Indian ricegrass, is the primary native plant community of the park. Bunchgrasses, such as little bluestem, sideoats grama, sand dropseed and threeawn, grow on rocky soils and bases of outcrops. A few communities of tall grass prairie are present, left from cooler, wetter times.
Submergent and emergent wetland and riparian plant communities are well established because of the reservoir. Sandbar willow dominates the riparian scrubland that occurs in areas protected from wave action. Plains cottonwood with a strong component of peach leaved willow exists along the reservoir shore. Plains draw scrubland and rabbitbrush scrubland grow where the water table is deeper under the surface and/or sites have more alkaline soils.