The Cariboo Region includes the Quesnel, Williams Lake, 100 Mile House, Chilcotin and Horsefly Forest Districts. Nearly 60% of the grasslands in the region are found along the Fraser River Basin, distributed along valley walls, river terraces and benches from Big Bar north to Williams Lake. The hottest and most arid portions of the region are lower grasslands, containing bluebunch wheatgrass and big sage. Middle grasslands are dominated by bluebunch wheatgrass and needle-and-thread grass, while the upper grasslands are dominated by porcupinegrass, bluebunch wheatgrass, spreading needle grass and Rocky Mountain fescue.