Which consumes more fossil fuels, lawn maintenance with gas-powered tools or lawn watering? For residents of Southern California, the correct answer is watering because of the energy it takes to transport water to the region.
Southern California (SoCal) is a semi-arid desert. Rainfall averages only 15 inches per year, for example, in the Los Angeles area. Local water sources have fallen far short of meeting the region's water needs for more than a century.
With 2/3 of the state's rainfall in Northern California and 2/3 of the water demand in SoCal, the state deals with this imbalance by pumping in half of SoCal's water supply from sources hundreds of miles away, the Colorado River and the Sacramento-San Joaquin Delta.
The Water-Electricity Relationship
Piping water long distances is costly in terms of electricity, especially water imported from the Delta which has to be pumped uphill 2,000 feet to get over the Tehachapi Mountains.
In a first ever analysis of the energy embedded in bringing potable water to residential faucets and hoses in SoCal, a 2005 California Energy Commission analysis calculated 11,111 kWh/MG (kilowatt hours per million gallons), three times costlier than in Northern California. Most of the electricity is for water transportation, much less for water treatment and maintaining water pressure. Every 100 gallons of imported water eats up enough electricity to keep a 100-Watt bulb lit for 11 hours.
California and the Colorado River are both in the grip of prolonged droughts, and water imports to SoCal from the Delta have been curtailed because of environmental problems there. SoCal's water reserves, already at near critical levels, are projected to dwindle further with population growth.
In November 2009, Governor Schwarzenegger signed a package of reform bills which included plans to restore the Delta ecosystem and mandate a statewide reduction of 20% per capita water use by 2020. While these measures might improve the reliability of water supplies in the future, the onus for achieving conservation is placed on water suppliers with no specific pressure on the public to curb wasteful water practices.
According to the Metropolitan Water District of Southern California (MWD), up to 70% of residential water use in SoCal is for outdoor irrigation, and lawns are a principle consumer. Domestic water use in California averages 124 gal/day/person, exceeding the national average by over 25 gal based on U.S. Geological Survey...