Terrestrial water storage in the western United States was studied using a combination of satellite data, surface observations, and modeling. The researchers found that evapotranspiration estimates matched observed precipitation well over long periods. Water storage in reservoirs accounted for a significant portion of the seasonal water cycle. The study also revealed that human activities have altered water storage patterns in the region. Additionally, satellite and surface observations showed different results compared to modeling estimates, indicating discrepancies in how water storage changes are understood.