Science Source

U.S. Department of the Interior, Bureau of Reclamation

USBR

Published date March 15, 2016

Reclamation: Managing Water in the West: Sacramento and San Joaquin Rivers Basin Study

Evaluates the effects of projected 21st century climate changes along with assumptions about potential population increases and land use changes
Finds that climate impacts include:
- Temperatures are projected to increase steadily during the century, with changes generally increasing from about 1.6 degrees Fahrenheit (°F) in the early 21st century to almost 4.8°F in the Sierra Nevada Mountains by late in the 21st century
- Precipitation may be only slightly changed especially early in the century with a trend toward increased precipitation in the Sierra Nevada in the late century; however, increased forest evapotranspiration due to warming may reduce runoff from mountain watersheds
- Snowpack will likely decline considerably due to warming particularly in the lower elevations of the mountains surrounding the Central Valley
- Runoff will increase during fall and winter months; peak runoff may shift by more than a month earlier in some watersheds; spring runoff will decrease due to reduced winter snowpack
- Sea levels are expected to increase; however, there is considerable uncertainty about the magnitude of increase—which may range from as little as 20 inches to as much as 55 inches in the Sacramento-San Joaquin Delta (Delta) by the end of century