By Vincent Lazaneo.
Most of the plants in our gardens require more water than local rainfall can provide. We irrigate many plants to keep them healthy and should know where the water comes from. This knowledge may influence the choices you make on how to use water.
Clean, fresh water flowing from a faucet is a convenience we do not fully appreciate, and this is even more true since we often use sub-surface irrigation methods on late-night timer settings for our gardens that further diminish our water use awareness. Consider how many trips to a store you would need to make to bring home 748 gallons. That’s the amount of water in 100 cubic feet (HCF), and you probably see a lot of HCFs on every water bill.
Water From Near and Far
Our region is semi-arid with frequent droughts, and scientists predict it will become drier and warmer due to climate change. San Diego County has relatively few aquifers and no major rivers, but we still use a lot of water. In 2017, San Diego delivered on average 200 million gallons of water per day to its customers and only 15% came from local sources. Most of the water we use comes from the Colorado River and from Northern California, and our reliance on imported water will continue even as we obtain more water locally from desalination and reclamation.
We began extracting fresh water from the Pacific Ocean in 2015, when the Carlsbad Desalination Plant was completed. The plant produces nearly fifty million gallons of fresh desalinated water daily that is pumped through a ten-mile long pipe to an aqueduct connection facility in San Marcos. The water is purchased under a thirty-year contract by the San Diego County Water Authority, which supplies water to member districts for retail sale.
One way to make water go further is to use it more than once. San Diego recently decided to produce potable water from recycled wastewater. Last month, the City Council approved the first phase of the Pure Water San Diego water purification and recycling program. The new North City Pure Water Facility, scheduled to open in 2021, is expected to initially deliver 30 million gallons of recycled water daily. The water will be stored in Miramar Lake and treated again before it is distributed to households. By 2035, the program’s three facilities could provide a third of San Diego’s water supply by recycling up to 83 million gallons of wastewater daily.
About 30% of the water that flows from taps in southern California comes from northern California via the State Water Project. The system transports water through the Sacramento–San Joaquin Delta, but this critical hub could soon fail. The Delta’s 1100-mile levee system is increasingly vulnerable to earthquakes, flooding, saltwater intrusion, sea level rise, and environmental degradation. The proposed solution, California WaterFix, would modernize the state’s water delivery system by building three new water intakes in the northern delta and two tunnels to carry the water under the Delta to the existing aqueduct system in the southern Delta.
Full funding for WaterFix, estimated to cost 16.7 billion dollars, was secured on April 10 when the board of the Metropolitan Water District of Southern California authorized 10.8 billion dollars to complete the project. People and businesses who use water delivered by WaterFix will ultimately pay for the project, which is estimated to take fourteen years to complete.
Vincent Lazaneo is UC Urban Horticulture Advisor Emeritus. He has a master’s degree in horticulture and a teaching credential in vocational agriculture from UC Davis. In 1983, Vince began the Master Gardener program in San Diego. Vince frequently contributes, or has contributed to, the San Diego Union-Tribune, Mira Mesa Living, and other publications, and he enjoys growing specialty plants in his home garden, reading, hiking, and fishing.