Study highlights:

River basins experience low-flow periods seasonally, either during the dry summer or, in some regions, during the winter, when precipitation is stored as snow and ice. Understanding low-flow periods is important for meeting the needs of river ecosystems, water use and supply, and energy production.

 Our study looks to answer these questions about annual low-flow periods in the conterminous United States:  

1. How long are low-flow periods and when do they typically start and end? 
2. How are these properties changing through time?
3. How does climate influence these properties? 

We found that the northwestern and eastern U.S. have longer low-flow periods with more consistent timing and duration from year to year compared to other regions. For most of the U.S., low-flow periods have become shorter from 1951-2020 except for the Northwest and Southeast, where they have become longer. Precipitation deficits affect low flows across the U.S., especially in the East, while temperature was most impactful on low flows in the Southeast and Northwest.