The drought of 2012 – 2015 has been unprecedented in California’s history. The Sierra Nevada snowpack of 2015 was the lowest in 500 years, and by summer 2015 California was in the midst of a 1-in-1200 year drought. Record-low rainfall, minimal Sierra Nevada snow pack, reduced runoff, and massive reductions in reservoir storage triggered widespread drought adaptation measures for one of the world’s largest economies. In this talk, I will describe what caused the Great California Drought, demonstrate some of its environmental consequences, and discuss the latest information on whether the current El Niño conditions in the tropical Pacific Ocean will provide some relief in the form of a wet winter.