Ventura County, California: drinking water report. Ventura County lies between Los Angeles and Santa Barbara, home to about 840,000 residents.
Ventura County lies between Los Angeles and Santa Barbara, home to about 840,000 residents. Water sources include local groundwater from multiple basins, the State Water Project, and the Casitas Municipal Water District's Lake Casitas. The county's agricultural sector – strawberries, citrus, avocados – is a major water user and a source of agricultural runoff that affects groundwater quality in several basins.
Ventura County's groundwater basins face a range of contaminants. The Oxnard Plain basin has documented seawater intrusion along the coast, while inland basins carry nitrate from agricultural operations. According to the California State Water Resources Control Board, six public water systems in the county exceeded nitrate MCLs during the most recent compliance period.
UCMR5 data shows PFAS detections in several county water systems. Naval Base Ventura County (formerly Point Mugu and Port Hueneme) is a confirmed PFAS source. The California SWRCB's monitoring data shows PFAS above state notification levels at seven public water systems in the county.
Coastal communities face seawater intrusion; inland communities face agricultural contamination; areas near the naval base face PFAS. The specific threat depends on geography.
Check your water for data mapped to your provider and ZIP code. Reverse osmosis handles all three concern areas – saltwater minerals, nitrate, and PFAS. Our water filter guide covers options. Pull your detailed report, and see our California page for statewide data.
Drinking water is one exposure route. These federal datasets also cover Ventura County, CA.
The EPA places Ventura County, CA in Zone 1 - the EPA's highest-risk category, where the predicted average indoor radon level is above 4 pCi/L. Zone maps predict an area's radon potential from geology and existing indoor readings; they say nothing about a specific house. Testing is the only way to know your own level.
57% of homes in Ventura County, CA were built before 1980, and 6% before 1950. Residential lead paint was banned in 1978, so housing age is the strongest available proxy for lead-paint exposure. This describes the county's housing stock, not any one home.
Modelled annual fine-particle pollution (PM2.5) in Ventura County, CA averages 7.3 µg/m³, within the EPA's annual standard of 9 µg/m³. These are CDC modelled county estimates rather than readings from a specific monitor.
How radon zones work · Air quality by county · Lead exposure guide