The Last Survivors (2014) online

At the edge of an expansive barren valley, all that remains of The Wallace Farm for Wayward Youth is a few hollowed-out husks of buildings. Seventeen year-old Kendal (Haley Lu Richardson) can barely recall when the Oregon valley was still lush. It's been a decade since the last rainfall, and society at large has dried up and blown away. Kendal and the few others that remain barely scrape by, while dreaming of escape. When a greedy water baron lays claim to what little of the precious resource remains underground, Kendal must decide whether to run and hide or bravely fight for the few cherished people and things she has left.