Drivers of Drought in the Upper Colorado River Basin

Science Center Objects

The purpose of this project is to investigate Colorado River basin droughts, and the role of temperature in influencing runoff efficiency. The project uses paleoclimatic data to extend instrumental climate and flow records, along with projected warming to assess the range of possible conditions that may be expected to occur and to determine how warming temperatures may influence river flow and water supply in the future.

Colorado River Basin map

Research Questions

This collaborative project, between researchers and water resource practitioners, has four main sets of stakeholder-driven questions:

  1. If 20th century-type droughts (i.e., 1950s) under 21st century temperatures are the new “normal” for drought, how might such droughts impact upper Colorado River flow (UCRB)?
  2. What do reconstructions of past precipitation from tree rings, combined with warming temperatures to generate estimates of water year streamflow (representing both long-term natural moisture variability and anthropogenic warming), suggest as plausible scenarios and characteristics of future UCRB drought over the next half century
  3. What are the major controls on annual UCRB streamflow efficiency (i.e. the proportion of precipitation that contributes to streamflow) and how are they related to temperature, level of flow, evapotranspiration, snow dynamics, and basin elevation?
  4. Given instrumental records for the 20th and 21st centuries, what were the contributions of antecedent soil moisture, seasonal temperatures, and cool and monsoon season precipitation to periods of high and low flow in the lower Colorado River basin (LCRB)? Can tree-ring reconstructions be used to evaluate these contributions in the context of past centuries?

In addition, this project includes a preliminary investigation of some potential impact of future droughts on ecosystem health in the upper Colorado River basin.


Project Resources

2017-2019 Project: Disentangling the Influence of Antecedent Temperature and Soil Moisture on Colorado River Water Resources

2014-2017 Project: Anticipating Future Impacts on Streamflow using Multi-Century Climate Records and Applied Hydrologic Models


Papers and Data Resources


Woodhouse, C. A. and G. T. Pederson, 2018. Investigating runoff efficiency in upper Colorado river streamflow over past centuries. Water Resources Research, 54.

Pederson, G.T, and Woodhouse, C.A., 2017, Multi-century reconstructions of temperature, precipitation, and runoff efficiency for the Upper Colorado River Basin: U.S. Geological Survey data release,

McAfee, S.A., G.T. Pederson, C.A. Woodhouse, G. J. McCabe. 2017. Application of synthetic scenarios to address water resource concerns: A management-guided case study from the Upper Colorado River Basin, Climate Services 8, 26-35,

McCabe, G., D. Wolock, G. Pederson, C. Woodhouse, and S. McAfee.  2017.  Evidence that recent warming is  reducing  upper  Colorado  River  Flows.  Earth Interactions,

Woodhouse, C.A., G.T. Pederson, K. Morino, S.A. McAfee, G.J. McCabe. 2016. Increasing Influence of Air Temperature on Upper Colorado River Streamflow. Geophysical Research Letters 43. 

Contact Greg Pederson,, or Connie Woodhouse,, for a copy of the paper.






Southwest Climate Science Center Project: Disentangling the Influence of Antecedent Temperature and Soil Moisture on Colorado River Water Resources

Final Workshop at Salt River Project


Data and Tools



Project Personnel

Connie Woodhouse – University of Arizona, Tucson AZ (
Gregory Pederson – U.S. Geological Survey, Bozeman MT (
Adam Csank – University of Nevada, Reno
Stephanie McAffee – University of Nevada, Reno
Gregory McCabe – U.S. Geological Survey, Denver CO
Stephen Gray – U.S. Geological Survey, Anchorage AK

Water Management Partners

Dave Kanzer – Colorado River District, CO
Eric Kuhn – Colorado River District, CO
Charlie Ester – Salt River Project, AZ
James Walter – Salt River Project, AZ
Laurna Kaatz – Denver Water, CO
Jim Prairie – Bureau of Reclamation,  Upper Colorado Region
Carly Jerla – Bureau of Reclamation, Lower Colorado District
Ken Nowak – Bureau of Reclamation,  Research and Development Office
Subhrendu Gangopadhyay – Bureau of Reclamation, Technical Service Center
Paul Miller – NOAA Colorado Basin River Forecast Center 


This project is funded by the DOI Southwest Climate Science Center (grant numbers . G14AP00152 and G17AP00099), and the NOAA Climate Assessment for the Southwest.