Last year the Public Policy Institute of California published an interactive map on its website. When you mouse over each hydrologic region of the state, it shows how the population and per capita urban water use in that region has changed since 1960. The map was released in December as part of a report on California Water Myths, which highlights eight common water myths.

Despite a steadily increasing population, most regions of the state began cutting back per-capita water use after the drought in the early 1990s. In fact, all regions used less water per capita in 2005 than in 1995. Population growth eroded these gains in 6 of the 10 regions. The four coastal regions that saw a decrease in total water use (i.e. conservation decreasing use kept up with population increasing use) during this period were:

South Coast                  -406.3 million gallons per day (mgd) (-12%)
San Francisco Bay       -149.5 mgd (-15%)
Central Coast                 -25.3 mgd (-11%)
North Coast                   -17.0 mgd (-13%)

The South Coast Region from Ventura to San Diego, which includes Los Angeles, had the biggest reduction, using about 406 million gallons per day less water in 2005 than in 1995. This region accounts for 90% of the statewide net reduction in urban water use of about half a million acre-feet per year during this period. San Francisco Bay had the best effort—a 15% reduction in urban use, adding up to 33% of the statewide reduction. Eroding these gains were all the inland regions, which increased their total urban water use during this time:

Colorado River             +52.8 mgd (+12%)
San Joaquin River       +43.8 mgd (+8%)
Sacramento River        +33.4 mgd (+5%)
Tulare Lake                    +12.4 mgd (+2%)
South Lahontan            +3.1 mgd (+1%)
North Lahontan            +1.0 mgd (+3%)

In 2005 the  Colorado River region (Imperial and parts of Riverside and San Bernardino County) used the most urban water, at 599 gallons per person per day—about four times what a typical Central Coast resident uses. The South Coast, where Mono Basin water supplies a portion of the demand of the city of Los Angeles (where single family homes averaged 117 gal/person/day last year), was using 176 gallons per person per day, coming in third behind the Central Coast’s 151 gallons per person per day,  and the San Francisco Bay Region’s 154 gallons per person per day.

Californians,  you can do better than this! As we head into the warm irrigation season, replace a portion of your lawn with native plants, or replace your old washing machine with a high-efficiency front-loading type that will save electricity too and make your clothes last longer. Visit our Water Conservation Tips page for more ideas. And thank you for your efforts to save water, which save places like Mono Lake.

Tags: conservation, population, urban, water

This entry was posted on Wednesday, March 17th, 2010 at 2:48 pm and is filed under News, Statewide Water Policy. You can view No Responses on this post or leave your own response if you log in.