What source? A link would be nice.
As an aside, there is nothing to "worry" about with regards to the Colorado river. We're way, way past worrying. It's not been a "might" situation for a long time. It's been badly overdrawn and subject to declining inflows and rainfalls.
Don't worry, abandon.
Karl Popper's falsifiability says we only need to prove this didn't happen once.
Your move, denialists.