In February and March, heavy rainfall fell in Southern California. That was good news for the City of San Fernando, as it captured 220 acre-feet of runoff, thanks to its groundwater infiltration system.
“Typically, a household uses about a quarter acre-foot of water [annually],” Wendell Johnson, director of Public Works, explained. “Essentially, the amount of water about 800 households on an annual basis has been infiltrated.”
While certainly a large amount of water, Johnson said it’s still only about half of their goal of capturing 450 acre-feet for the year – enough for 1,800 households.
Completed in late 2023, the system was installed to collect runoff from three storm drains in the city. It removes any impurities from the water and conveys it to an underground system to be infiltrated. The system can capture up to 25 acre-feet of runoff per storm.
The system is meant to protect local bodies of water, including the Pacoima Wash and Los Angeles River, from impurities while also supporting groundwater recharge for the San Fernando groundwater basin, which is used by the city of LA.
City of San Fernando residents don’t receive water from the basin. Their supply comes from the Sylmar basin, which it shares with the city of LA. However, if the San Fernando basin were to run dry, the city of LA would then resort to taking more from the Sylmar basin, directly affecting the supply for local residents.
“Any type of recharge at this time is giving us the capacity to do extraction in the future,” said Johnson. “Because we’re all connected together, the more we put in the San Fernando [groundwater basin], the less imported water Los Angeles uses and more that is available for neighboring communities outside of LA to use.”
The City of San Fernando also imported water from the Metropolitan Water District between 2022 and 2024 after one of the wells in the Sylmar basin had to be shut down due to a high concentration of nitrates.
According to the California Department of Public Health, consuming large amounts of nitrates can interfere with the oxygen-carrying ability of blood in infants and pregnant women. Some scientific studies also suggested links between high nitrate levels and birth defects and certain cancers.
The City of San Fernando has four extraction wells: 2A, 3, 4 and 7A. Well 2A, which alone could provide all the water needed for the city, is the only one currently not in service. Nitrate removal systems have been installed in each of the other three wells.
Johnson said they are moving ahead and designing a system for Well 2A. They are still deciding between an ion exchange system, which reduces nitrates in the water, or a blending system that would dilute the contaminated water in Well 2A with low-nitrate water from another well.
By September, he said the city will likely have public hearings and workshops to discuss the final design and construction schedule. Depending on the option they go with, Johnson said, the system should be online by this time next year.