Science

Warming, compounded by less frequent precipitation, will worsen droughts and threaten our imported and local water sources.

The science and why it matters:

  • Our water demand is expected to increase by 46 percent by 20351  due to our growing population, rising temperatures, longer intervals without rain and increased evaporation from the soil and water reservoirs.
  • Local water supplies will be under stress from more intense and frequent drought, as well as from more evaporation and increasing water demand due to rising temperatures.
  • Water availability from both the Sierra Nevada (via the State Water Project) and the Colorado River will also be under more stress from warming temperatures and more extended droughts that reduce the amount of snowpack and river flow.
  • The potential for diminished water availability from imported water sources will increase the need to meet regional water demands through new local supply development such as water reuse and seawater desalination, as well as increase the need to stretch available supplies through efficient water use practices.

A word from the scientists

“Our history is written in water, not ink. Our future prosperity depends upon a stable and secure water supply, which is increasingly imperiled from climate change and growing demand. In coming years, we will need to take much more aggressive action to expand water conservation, recycling and storage.”

Charlie Kennel, PhD

Professor and Director Emeritus, Scripps Institution of Oceanography, UC San Diego, and Former Director, Mission to Planet Earth, NASA

Charlie Kennel


Water Supply Infographic

Water in San Diego County

With most of San Diego County's water being imported2 and an expected decrease in streamflow3, how we manage and use our water is vital to our region's prosperity. Currently, the bulk of water demand in San Diego is for residential use, more than half of which is used for landscaping.4,5

1. San Diego County Water Authority. 2011. Urban Water Management Plan.

2. San Diego County Water Authority. 2013. 5-year average, FY 2009-2013. (Local supplies excludes reclaimed water.)

3. Das, T., D.W. Pierce, D.R. Cayan, J.A. Vano and D.P. Lettenmaier, 2011: The importance of warm season warming to western U.S. streamflow changes. Geophysical Research Letters, 38, L23403, doi:10.1029/2011GL049660

4. San Diego County Water Authority. 2012. FY 2012 Estimated Sectoral Water Use. San Diego County Water Authority FY2012 Annual Report.

5. DeOreo, W.B., Mayer, P.W., Martien, L., Hayden, M., Funk, A, Kramer-Duffield, M., Davis, R., Henderson, J., & Gleick, P. 2011. California Single Family Water Use Efficiency Study. Sponsored by the California Department of Water Resources.