In an April 12, 2012, post to the New York Times Op-Docs, a forum for short, opinionated documentaries, produced with creative latitude by independent filmmakers and artists, Academy Award-winning filmmaker Jessica Yu writes about the water crisis in the United States. She is the director of the forthcoming “Last Call at the Oasis,” a feature documentary on the water crisis for Participant Media.  Her nonfiction and scripted films include “Protagonist,” “Ping Pong Playa” and “In the Realms of the Unreal.”