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Mariposa County, California: environmental and disease records

Cancer mortality in Mariposa County is 127.1 deaths per 100,000 people per year against a U.S. rate of 143.2. Federal databases place 93 regulated facilities, sites and hazards inside the county, led by NPDES wastewater discharge permit (34), Gas station (mapped facility) (13), Small hazardous waste generator (10). EPA AirToxScreen estimates a lifetime cancer risk from outdoor air toxics of 40 in a million, driven mainly by formaldehyde.

Rates are age-adjusted per 100,000 people. A cancer signal is marked significant when the lower bound of its 95 percent confidence interval is above the U.S. rate. Facility counts use active federal records located inside the county boundary. Approximate county center: 37.5435, -119.9583.

How this county ranks in California

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Cancer deaths and new cases versus the United States

Source: NCI and CDC State Cancer Profiles, both sexes, all ages. Sorted by the ratio of the county rate to the U.S. rate.

Cancer rates for Mariposa County compared with the United States
Cancer	Measure	County rate	U.S. rate	Times U.S.	95% interval	Years
Melanoma of the skin	New cases	31	23.8	1.3x	21.8 to 43.3	2019-2023
Thyroid	New cases	15.8	13	1.22x	8.1 to 27.8	2019-2023
Pancreas	Deaths	13.2	11.3	1.17x	8.5 to 21	2020-2024
All cancer	New cases	459	453.4	1.01x	422.1 to 498.8	2019-2023
Lung & bronchus	New cases	50.5	51.8	0.97x	40.3 to 63.4	2019-2023
Bladder	New cases	18.2	18.7	0.97x	12.6 to 26.8	2019-2023
All cancer	Deaths	127.1	143.2	0.89x	109.8 to 147.2	2020-2024
Lung & bronchus	Deaths	26.5	30.2	0.88x	19.5 to 36.4	2020-2024
Kidney & renal pelvis	New cases	15.1	17.9	0.84x	9.1 to 24.4	2019-2023
Non-Hodgkin lymphoma	New cases	14.8	18.5	0.8x	8 to 25.5	2019-2023
Pancreas	New cases	10.7	13.9	0.77x	6.6 to 18	2019-2023

Mortality measures versus the U.S. county median

Source: County Health Rankings, built from CDC National Vital Statistics System death records. The comparison value is the median of all U.S. counties.

Mortality measures for Mariposa County
Measure	County	U.S. median	Difference	Unit
Premature death	9,759.3	9,842.6	-1%	years of life lost before age 75 per 100,000
Life expectancy	78.3	75.3	+4%	years
Child mortality	n/a	59.8	n/a	deaths under age 18 per 100,000
Infant mortality	n/a	6.2	n/a	deaths under age 1 per 1,000 live births
Injury deaths	114	96.9	+18%	deaths per 100,000
Drug overdose deaths	31.2	28.6	+9%	deaths per 100,000

Air toxics and air quality

EPA AirToxScreen 2020

Lifetime cancer risk from outdoor air toxics: 40 in a million. EPA treats 100 in a million as the upper end of acceptable risk and 1 in a million as the goal.

Formaldehyde31.01 per million
Acetaldehyde3.78 per million
Carbon Tetrachloride2.73 per million
Pahpom2.04 per million

EPA Air Quality Index 2025

Monitored on 340 days: 274 good, 0 unhealthy for sensitive groups or worse. Median AQI 44, peak 90.

Regulated facilities, sites and hazards by type

93 active records inside the county from EPA ECHO, TRI, Superfund, Brownfields, NPDES, EIA, FAA, FRA and corrections data.

NPDES wastewater discharge permit34
Gas station (mapped facility)13
Small hazardous waste generator10
Large hazardous waste generator9
Industrial wastewater discharge8
Hazardous waste transporter5
EPA air quality monitor3
Hydroelectric plant2
Wastewater plant (mapped facility)2
Public airport1
Commercial airport1
Auto repair or body shop (mapped facility)1
Heliport1
Landfill (mapped facility)1
Scrapyard (mapped facility)1
Toxic chemical release facility (TRI)1

Highest-severity records

The 25 records with the highest Envyrofax severity in the county, with the agency identifier to cite in a records request.

Us Natl Park Service Yosemite Natl Park, Yosemite National Park
Toxic chemical release facility (TRI). Chemicals: Lead. Reports carcinogens. 380 lbs released over 5 years.
TRI facility ID 95318SNTNLPOBOX (U.S. EPA Toxics Release Inventory)
Severity 6.5
Us Natl Park Service Yosemite Natl Park, El Portal
Large hazardous waste generator.
EPA FRS registry ID 110041960679 (U.S. EPA ECHO) Agency record
Severity 5.8
Us Natl Park Service Yosemite Natl Park, El Portal
NPDES wastewater discharge permit.
EPA FRS registry ID 110041960679 (U.S. EPA ECHO) Agency record
Severity 5.8
Yosemite Hospitality Llc, Yosemite
Large hazardous waste generator.
EPA FRS registry ID 110001128226 (U.S. EPA ECHO) Agency record
Severity 3
Tavis Corporation, Mariposa
Large hazardous waste generator.
EPA FRS registry ID 110005995717 (U.S. EPA ECHO) Agency record
Severity 3
Pacific Bell, Yosemite National Park
Large hazardous waste generator.
EPA FRS registry ID 110008292686 (U.S. EPA ECHO) Agency record
Severity 3
Pacific Bell, Yosemite National Park
Large hazardous waste generator.
EPA FRS registry ID 110008292695 (U.S. EPA ECHO) Agency record
Severity 3
Pacific Bell C/O Cd Packer Ue532, Coulterville
Large hazardous waste generator.
EPA FRS registry ID 110018983787 (U.S. EPA ECHO) Agency record
Severity 3
Rite Aid #6443, Mariposa
Large hazardous waste generator.
EPA FRS registry ID 110042181180 (U.S. EPA ECHO) Agency record
Severity 3
Jes Land Company, Catheys Valley
Large hazardous waste generator.
EPA FRS registry ID 110069707302 (U.S. EPA ECHO) Agency record
Severity 3
Laue Abandoned Mine Site, Bear Valley
Large hazardous waste generator.
EPA FRS registry ID 110070796916 (U.S. EPA ECHO) Agency record
Severity 3
Mariposa Pud Wwtf, Mariposa
NPDES wastewater discharge permit.
EPA FRS registry ID 110006783515 (U.S. EPA ECHO) Agency record
Severity 2.3
Mariposa Cnty Landfill, Mariposa
NPDES wastewater discharge permit.
EPA FRS registry ID 110070088692 (U.S. EPA ECHO) Agency record
Severity 2.3
Iron Spring Consolidated, Mariposa
NPDES wastewater discharge permit.
EPA FRS registry ID 110070088694 (U.S. EPA ECHO) Agency record
Severity 2.3
Outback Materials Mariposa Plant, Mariposa
NPDES wastewater discharge permit.
EPA FRS registry ID 110070356699 (U.S. EPA ECHO) Agency record
Severity 2.3
Butterfly Creek Winery, Mariposa
NPDES wastewater discharge permit.
EPA FRS registry ID 110070095045 (U.S. EPA ECHO) Agency record
Severity 2
Mariposa-Yosemite, Mariposa
Commercial airport. O.
Record ID MPI (FAA / U.S. DOT)
Severity 2
Wawona Wastewater Treatment Facility
Wastewater plant (mapped facility). Mapped facility presence only; no compliance or exposure measurements.
Record ID way/1354305373 (OpenStreetMap contributors) Agency record
Severity 2
Landfill
Landfill (mapped facility). Mapped facility presence only; no compliance or exposure measurements.
Record ID way/220685663 (OpenStreetMap contributors) Agency record
Severity 2
MPUD
Wastewater plant (mapped facility). Mapped facility presence only; no compliance or exposure measurements.
Record ID way/76122125 (OpenStreetMap contributors) Agency record
Severity 2
Mariposa County Road Dept, Mariposa
Small hazardous waste generator.
EPA FRS registry ID 110002897250 (U.S. EPA ECHO) Agency record
Severity 1.5
Mariposa Agri Comm, Mariposa
Small hazardous waste generator.
EPA FRS registry ID 110002944887 (U.S. EPA ECHO) Agency record
Severity 1.5
Goldenbell Mining Corp, Mariposa
Small hazardous waste generator.
EPA FRS registry ID 110005995511 (U.S. EPA ECHO) Agency record
Severity 1.5
Cal Trans, Midpines
Small hazardous waste generator.
EPA FRS registry ID 110005995959 (U.S. EPA ECHO) Agency record
Severity 1.5
Dohs-Mariposa Co, Mariposa
Small hazardous waste generator.
EPA FRS registry ID 110008267632 (U.S. EPA ECHO) Agency record
Severity 1.5

Correctional facilities

Prisons, jails and corrections operations with an EPA facility record, and the drinking water and wastewater compliance attached to them.

No correctional facility with an EPA record is located in this county.

Discovery / public records

Records to request for Mariposa County

California state cancer registry
Cancer incidence counts by census tract or ZIP code, by cancer type and year (de-identified). Any cancer cluster inquiries or investigations in Mariposa County, and their findings.
California vital statistics office
Death certificate counts by cause of death and residence tract or ZIP code, and the years behind the mortality measures above.
California health department, environmental epidemiology
Health consultations or assessments by ATSDR or the state health department covering the county, and any exposure investigations.
California environmental agency and the U.S. EPA regional office
Compliance history, inspection reports, notices of violation, penalties and enforcement actions for each facility above, cited by EPA FRS registry ID.
California drinking water program
Violation notices, sampling results and sanitary surveys for the public water systems serving the county, including any system serving a correctional facility.
Department of corrections or county sheriff
Water testing, grievances and environmental health inspections for the correctional facilities listed above.

Each Envyrofax address report includes a printable records request worksheet with the custodian and the exact request wording per finding.

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