Some new research published in Proceedings of the National Academy of Sciences shows that states in the Western US are likely in for much drier conditions in coming decades from climate changes. Both human-caused climate change and because of naturally-occurring wet and dry cycles getting longer, particular since 1000 CE. Which in the broad stroke we already knew.
The really notable part is this, from lead-researcher Mark Abott, from Pitt University:
"Western states happened to build dams and water systems during a period that was unusually wet compared to the past 6,000 years. Now the cycle has changed and is trending drier, which is actually normal. It will shift back to wet eventually, but probably not to the extremes seen during most of the 20th century.In fact the wet cycle experienced from 1940-2000 was the dampest period in the Western US for the past 350 years.