Lake Los Angeles Water Hardness & Quality Report (2026)

Waterworks District No. 40, operated by Los Angeles County Public Works, serves Lake Los Angeles in the Antelope Valley region of northern Los Angeles County, California. The utility supplies approximately 62% treated surface water primarily from the California State Water Project via the California Aqueduct and 38% groundwater from local Antelope Valley wells. Treatment occurs at facilities processing imported surface water for disinfection and blending with pumped groundwater prior to distribution to this unincorporated community of about 14,000 residents spanning over 20 square miles.

The surface supply originates from the Sacramento-San Joaquin River Delta watershed, managed through the State Water Project, flowing via aqueducts across Central Valley alluvial plains and Tehachapi Mountains. Locally, groundwater taps the Antelope Valley Groundwater Basin, a sub-basin of the Mojave Desert system bounded by the San Gabriel and Tehachapi Mountains. Geology features unconsolidated Quaternary alluvium over older Tertiary sedimentary layers with abundant carbonate-rich formations like the Monterey Formation equivalents, imparting a hard character through mineral dissolution; surface waters pick up ions en route while groundwater equilibrates with limestone-bearing aquifers, yielding a moderately mineralised to hard supply.

At this hard level, scale buildup is common in pipes, water heaters, dishwashers, and washing machines, reducing efficiency by 20-30% over time and increasing energy bills. Showers may feel less soapy, leaving residue on skin and hair, while laundry detergents underperform. Maintenance includes monthly vinegar descaling for appliances, installing scale-inhibiting showerheads, and using high-efficiency detergents. A water softener is recommended to extend appliance life and improve cleaning. Water meets state and federal standards per 2021 reports, with pH typically 7.5-8.5 from blending. Lead and copper rule compliance achieved via corrosion control; no exceedances noted. PFAS data unavailable in provided sources. Groundwater may carry elevated total dissolved solids and naturally occurring arsenic managed by blending/treatment. Processes include chlorination, fluoridation for surface water, and blending at distribution points.