Ecologically, park uplands are dominated by pinyon-juniper woodlands, where Utah juniper, pinyon pine, mountain mahogany, Gambel oak, serviceberry, squaw-apple, Fendlerbush, Mormon-tea, skunkbrush and Spanish bayonet are overstory dominants. Western wheatgrass, Junegrass and galleta are common understory grass species in this community. 

Deeper soils of upland flats support a sagebrush shrubland community dominated by big sagebrush, rabbitbrush, four-wing saltbush, shadscale, prickly-pear, western wheatgrass, galleta and squirreltail. West Slope grassland occurs in pockets within and bands adjacent to woodland and shrub communities. 

The common grasses present include western wheatgrass, galleta and squirreltail. Diverse wetland, riparian and aquatic plant communities are established around the reservoir, within drainages, on ground water seeps and below the dam. Irrigated hay meadows have replaced native plant communities in much of the landscape surrounding the park.