Climate's Influence on Lower Colorado Streamflow

Researchers have long recognized the influence of warming temperatures on streamflow, but the practical implications for water management have received less attention. To address this gap, CLIMAS researchers worked with resource managers in Arizona to shape a research agenda focused on climatic controls on surface water supplies for three key rivers: the upper Gila, Verde, and Salt Rivers. The study found that cool-season precipitation remains the primary driver of annual streamflow. However, the summer monsoon plays a critical role—especially in the upper Gila River basin—by helping to offset the impacts of dry winters and multi-year droughts. The analysis also highlighted the increasing influence of temperature on water supplies, particularly during low-flow years and recent drought periods. These insights were especially valuable for major water utilities like the Salt River Project, which serves the Phoenix metro area. For more information, visit the project website.

“Connie’s research suggests results that we were expecting, but there wasn’t a lot of peer reviewed literature to support it before this project. The way we communicate to the U.S. Bureau of Reclamation and to customers about water resiliency projects is heavily informed by this CLIMAS research.”
- Bo Svoma, Salt River Project

CLIMAS Lead: Connie Woodhouse

Research Team: Dan Ferguson, Andrea Gerlak, Sarah Frederick, Talia Anderson

Partners: Flagstaff Water Services, Salt River Project

Publications

Woodhouse, C. A., & Udall, B. (2022). Upper Gila, Salt, and Verde Rivers: Arid Land Rivers in a Changing Climate. Earth Interactions, 26(1), 1–14. https://doi.org/10.1175/EI-D-21-0014.1

Lower Colorado River Basin Fact Sheets

Woodhouse, C., Ferguson, D. (2021). Verde River: Relationships between Climate and Streamflow. Climate Assessment for the Southwest, University of Arizona.

Woodhouse, C., Ferguson, D. (2021). Salt River + Tonto Creek: Relationships between Climate and Streamflow. Climate Assessment for the Southwest, University of Arizona.

Woodhouse, C., Ferguson, D. (2021). Upper Gila River: Relationships between Climate and Streamflow. Climate Assessment for the Southwest, University of Arizona.