Pacific Southwest Research Station

The effects of climate change on Lake Tahoe, and implications for design of best management practices

Principal Investigators:
John Reuter, University of California-Davis
Robert Coats, Hydroikos Ltd.

Proposal [pdf]

Final Report [pdf]

Additional Report
Coats et al. 2013 [pdf]

Please refer to the publication for the most recent information regarding this project. Please contact Dr. Robert Coats with questions regarding the publication.

Project Summary

The goals of this project were (1) to determine how climate change will affect the future clarity of Lake Tahoe and (2) determine how climate change will affect Best Management Practice (BMP) effectiveness. With down-scaled output from two General Circulation Models (the Geophysical Fluid Dynamics Laboratory, or GFDL, and the Parallel Climate Model, or PCM) and two emissions scenarios (A2 and B1), the research team projected future trends in temperature and precipitation for the Tahoe Basin.

With the GFDL, drought conditions were also projected and (through the use of a distributed hydrologic model) flood frequency. The steepest trend (GFDL with A2) indicates a 4–5°C warming by the end of the 21st century. Trends in annual precipitation are more modest with a dip in the latter half of the 21st century indicated by the GFDL/A2 case, but not the others.

Comparisons with the Palmer Drought Severity Index show that drought will increase, in part due to the declining role of the snowpack as a reservoir for soil moisture replenishment. Analysis of flood frequency for the largest watershed in the basin indicates that the magnitude of the 100-year flood could increase up to 2.5-fold for the middle third of the century, but decline thereafter as the climate warms and dries. These trends have major implications for the management of land and water resources in the Tahoe Basin, as well as for design and maintenance of infrastructure.