EPA-regulated facilities in Mariposa County, CA

There are 320 EPA-regulated facilities inside Mariposa County, California. The most common kinds are hazardous waste (181), drinking water systems (65), air emissions (56). 1 is currently in significant noncompliance, the EPA's designation for the most serious or persistent violations, and 11 have a violation on record.

Open the map of Mariposa County

320facilities in the county

1in significant noncompliance

11with a violation on record

$0in penalties, last 5 years

By category

Category	Facilities
Hazardous waste	181
Large quantity generators	9
Small quantity generators	13
Transporters	3
Chemical (RMP/TRI)	1
Superfund	5
Air emissions	56
Water discharge	21
Major permits	1
Minor permits	16
Drinking water systems	65
Scrap yards	1

A facility enrolled in several programs counts once in the total and once in each of its categories.

In significant noncompliance

The EPA's designation for its most serious or persistent violations, as of the latest data.

MARIPOSA PUD WWTF 4956 MILLER RD, MARIPOSA, CA, 95338 Significant noncompliance

Superfund sites

USDOJ BLM NEAREST CITY: MERCED FALLS, MARIPOSA, CA, 95338
EL PORTAL BARIUM TAILINGS INT OF FOREST & BARIUM MINE RD, EL PORTAL, CA, 95318
US NATL PARK SERVICE YOSEMITE NATL PARK NATIONAL PARK SERVICE, NPS, EL PORTAL, CA, 95318
EL PORTAL RR FLAT HWY 140, EL PORTAL, CA, 95318
SOLAMBO MINE NEAREST CITY LA GRANGE, COULTERVILLE, CA, 95311

Bordering counties

Reading these numbers

These are regulatory records, not measurements of pollution. Most facilities appear because they hold a permit or file reports, and most of them are compliant; a listing is not a claim that a facility has polluted anything. Compliance status and penalties are the EPA's own determinations in data retrieved Oct 9, 2026. The Data page explains where each record comes from and how it can mislead.