Droughts and wet periods in major Western watersheds often happen together, according to new research that shows how water conditions in one area can be closely tied to those hundreds of miles away. Researchers analyzed more than 20 years of satellite and climate data from five major areas: the Upper and Lower Colorado River basins, the Great Basin, California and the Pacific Northwest, including parts of Mexico and Canada. Together, those areas provide water to more than 60 million people and vast stretches of farmland. The researchers found some of the strongest connections between California and the Great Basin — which includes most of Nevada and much of Utah. Runoff conditions in the two areas were synchronized 65% of the time, while soil moisture moved together 67% of the time. Overall, six major watershed pairings had runoff conditions that were synchronized more than half the time.