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Review government records associated with San Dimas, California.
Toxin Scout is in beta. Please verify important findings with the linked sources.
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Preparing San Dimas environmental records...
Check your water bill for your utility name and confirm the reporting year. See EPA’s guide to finding your annual water quality report.
Public water-system records for San Dimas, CA from EPA SDWIS.
Gswc-San Dimas
PFAS above an official threshold detected in available EPA records.
Reviewed: active/open records as of Q1 2026
Purchased or imported water record · Serves 56,538 people
Data from EPA SDWIS
PFAS screening separates EPA UCMR5 drinking-water monitoring from nearby DoD PFAS investigation-site records; EPA samples shown are from Nov 2024.
Drinking Water PFAS Monitoring
EPA UCMR5 samples public water systems. These results are separate from nearby PFAS cleanup or investigation-site records.
1 PFAS sample result above EPA limits
Sample period: Nov 2024
UCMR5 results are sampled by public water system, not every household. Confirm your water provider before treating these as tap-water results for a specific address.
| Chemical | Concentration (µg/L) | EPA Limit (µg/L) | Sample date | Over Limit |
|---|---|---|---|---|
| PFOS | 0.0045 | 0.0040 | 2024-11-18 | Yes |
Nearby PFAS Investigation Sites
DoD records are nearby site investigations, not San Dimas drinking-water detections. Record names come from the source database and can be broad.
No DoD PFAS investigation records shown for this report.
EPA ATTAINS records identify assessed water bodies that do not meet water-quality standards for designated uses.
Big Dalton Wash
Reported: Nov 2026
Health-relevant causes: Mercury, Metals (other Than Mercury), Pathogens, Pesticides, Polychlorinated Biphenyls (pcbs)
Affected uses: Ecological, Fishconsumption, Other, Recreation
Data from EPA ATTAINS
NPDES permits regulate pollutant discharges into U.S. waterways. Facilities must report compliance quarterly.
Violation records
Last inspected: Dec 2025
Data from EPA ECHO
To investigate water contamination, check the sampling locations, dates and results below. For tap water records, see Drinking water quality above.
Reviewed: source records as of 2026
Review historical EPA air pollution records, including monitoring and facility emissions where available. For current conditions, check local air quality on AirNow.
Los Angeles County
Assessment year: 2020
According to EPA, a cancer risk of 40-in-1-million means that for every 1 million people continuously exposed to these air toxics over a 70-year lifetime, an estimated 40 may develop cancer from that exposure. This is in addition to cancer risk from all other causes.
Top modeled source groups
Data from EPA AirToxScreen
EPA designates an area as nonattainment when air quality does not meet federal health-based standards (NAAQS) for a specific pollutant.
Los Angeles-South Coast Air Basin: Ozone
NonattainmentExtreme8-Hour Ozone (2015 Standard)
Original designation: Aug 2018
Health effects (EPA): Respiratory inflammation, aggravation of asthma, reduced lung function (EPA)
Los Angeles-South Coast Air Basin: PM2.5
NonattainmentSeriousPM-2.5 (2012 Standard)
Original designation: Apr 2015
Health effects (EPA): Cardiovascular disease, respiratory illness, premature death (EPA)
Los Angeles County-South Coast Air Basin: Lead
NonattainmentLead (2008 Standard)
Original designation: Dec 2010
Health effects (EPA): Neurological damage, kidney damage, developmental effects in children (EPA)
Data from EPA Green Book
EPA annual monitor summaries describe past measurements. For current air quality, see AirNow.
Anaheim
Annual mean: 0.3 Parts per million
Observation year: 2025
Annual mean: 19.0 Parts per billion
Observation year: 2025
Annual mean: 0.038 Parts per million
Observation year: 2025
Data from EPA AQS
Reviewed: source records as of Q4 2025
TRI releases are self-reported annual totals (calendar year 2024). Hover fugitive or stack for definitions.
Pomona Plant 5
Reported: 2024
Reviewed: source query run Nov 2026
Reviewed: source query run Nov 2026
State environmental agencies maintain cleanup site databases that include state Superfund, voluntary cleanup, and brownfield remediation programs. These programs track additional sites beyond those on the federal NPL.
2 sites with active cleanup or investigation
334 WEST BONITA AVENUE, SAN DIMAS
0.2 miles away · LOS ANGELES County
Reported: Nov 2026
304 WEST BONITA AVENUE, SAN DIMAS
0.2 miles away · LOS ANGELES County
Reported: Nov 2026
Data from EPA ECHO
Facilities with hazardous-waste handler records under RCRA in the reviewed 5-mile city-center search area. Active handler status is separate from air, water, or other ECHO compliance violations, which are shown in their own sections.
Active RCRA handler records in the reviewed city search area
No release reports shown in this group.
Reviewed: active/open records as of 2018
Data from EPA UST Finder
Toxics Release Inventory data — chemicals disposed on-site at reporting facilities.
Pomona Plant 5
Open data source: View EPA TRI facility recordNo MSHA mine or extraction site records shown for this report.
Los Angeles County, CA
EPA Radon Zone Map (June 2024 release)
Los Angeles County is EPA Radon Zone 2 (moderate potential). EPA defines Zone 2 counties as having predicted average indoor screening levels between 2 pCi/L and 4 pCi/L.
Radon levels can vary from home to home, so EPA recommends testing the property to know its indoor level.
FEMA flood zones describe mapped flood hazards. Look up a specific address with FEMA.
No FEMA flood-zone records shown for this report.
Results use an earlier stored RMP inventory. Current EPA ECHO location coverage is unverified.
EPA ECHO lists facilities linked to the Risk Management Program. Results include facilities with locations that can be matched. Records may be historical. Current operations, chemical inventories, and recent accident history are unverified.
PHMSA tracks incidents involving natural gas and hazardous liquid pipelines. Incidents include leaks, ruptures, and explosions.
Recent Incidents (last 5 years)
SOUTHERN CALIFORNIA GAS CO
Incident date: Oct 13, 2023
Property damage: $15,000
Data from PHMSA
Health outcomes from County Health Rankings. Values shown alongside state and national averages.
Los Angeles County, CaliforniaPop. 9,721,138
County Health Rankings edition: 2024
Premature Death
Poor or Fair Health
Poor Physical Health Days
Poor Mental Health Days
Adult Smoking
Adult Obesity
Air Pollution - Particulate Matter
Drinking water violation indicator
Diabetes Prevalence
Life Expectancy
| Indicator | County | State | National |
|---|---|---|---|
| Premature Death | 6,317 | 6,373 | 7,972 |
| Poor or Fair Health | 18.2% | 15.8% | 14.2% |
| Poor Physical Health Days | 3.5 | 3.1 | 3.3 |
| Poor Mental Health Days | 5.1 | 4.7 | 4.8 |
| Adult Smoking | 11.0% | 8.8% | 15.0% |
| Adult Obesity | 28.5% | 27.8% | 34.0% |
| Air Pollution - Particulate Matter | 13.4 | 7.1 | 7.3 |
| Drinking water violation indicator | Yes | N/A | N/A |
| Diabetes Prevalence | 11.7% | 10.8% | 9.6% |
| Life Expectancy | 80.1 | 79.9 | 77.6 |
EPA testing found PFAS in water samples from Gswc-San Dimas. Results dated Nov 18, 2024 include PFOS at 0.0045 micrograms per liter.
Check with the utility that serves your address for its testing results.
The EPA drinking water records available here list no violations for Gswc-San Dimas.
Check your water bill to identify the utility serving your address. Ask that utility about current drinking water advisories.
Nearby EPA monitoring stations provide annual air quality measurements for San Dimas.
The monitoring station at Anaheim recorded an annual average of 0.3 Parts per million for carbon monoxide in 2025.
The monitoring station at Anaheim recorded an annual average of 19 Parts per billion for nitrogen dioxide in 2025.
The monitoring station at Anaheim recorded an annual average of 0.038 Parts per million for ozone in 2025.
The radon data for San Dimas covers Los Angeles County. EPA places this area in Zone 2, with a predicted average indoor radon screening level of 2 to 4 picocuries per liter.
No Superfund or brownfield sites were returned for this city report.
The county data for San Dimas reports a life expectancy of 80.1 years in Los Angeles County, California.
The figure is from the 2024 edition of County Health Rankings, a University of Wisconsin program that publishes county health statistics.
The county data for San Dimas reports 6,317 years of life lost to deaths before age 75 per 100,000 residents in Los Angeles County, California. This measure adds up the years lost to early deaths and adjusts for differences in population age.
The figure is from the 2024 edition of County Health Rankings, a University of Wisconsin program that publishes county health statistics.
The county data for San Dimas lists fine-particle pollution (PM2.5) at 13.4 micrograms per cubic meter in Los Angeles County, California.
The figure is from the 2024 edition of County Health Rankings, a University of Wisconsin program that publishes county health statistics.
Federal pipeline records list an incident involving Sfpp, LP near San Dimas on Nov 4, 2010. The reported release was a liquid petroleum product.
Federal pipeline records list an incident involving Southern California Gas Co near San Dimas on Oct 13, 2023. The reported release was natural gas.