Ingram says that the 20th century stands out as a somewhat wetter century. During this time, California built all its reservoirs and water storage facilities. However the last few years have been drier than the last twelve hundred years. The last four years have been the driest during that twelve century period.
While all the American West has been dry during the past few years, California has been the driest. The U.S. Drought Monitor shows that California and Nevada have the worst of the drought that is afflicting the western states. Ingram says that it is hard to separate the part of the problem that is cyclical from the part that can be attributed to global warming. However, she points out that warming will reduce rainfall and snowpack, and warmer weather will produce more evaporation.
The el Niño weather phenomenon could theoretically bring more rain to California. However, Ingram says, the effect of an el Niño is hard to predict. It can produce more rain or a drought.
As to whether government policies could have made a difference, Ingram notes that California has developed dams and reservoirs on virtually every water source in the state. The existence of more effective regulations might have helped California avoid exhausting all its available groundwater.
B. Lynn Ingram is a Professor (Earth & Planetary Science and Geography) at the University of California-Berkeley. She is also the author of “The West without Water.” She supervises the Laboratory for Environmental and Sedimentary Isotope Geochemistry. One of her primary field areas is the San Francisco Bay estuary and watershed, where she has worked over the past ten years with three graduate students and one postdoctoral fellow. The Legal Broadcast Network is a featured network of the Sequence Media Group.