San Mateo, CA
Transparent derived index from EPA TRI / SDWIS / Superfund extracts: not an official EPA rating. Fixed caps: facilities ≤25 pts (50+ = max), log10 releases ≤25 pts, Superfund ≤25 pts (5/site), health-violation systems ≤15 pts (3/system), high-chemical facilities ≤10 pts. Bands: High ≥60, Moderate ≥30. See methodology.
Environmental data for San Mateo in California · Population: 745,100
TRI sites such as Csbio; Nxedge San Carlos; US Doe Slac National Accelerator Laboratory; SDWIS systems such as SFPUC CITY DISTRIBUTION DIVISION; CITY OF DALY CITY; CITY OF REDWOOD CITY anchor San Mateo, CA's EPA extract. Derived burden score 39/100 (Moderate Risk) uses fixed national caps on density, log release volume, Superfund count, and health-flagged systems - not an official EPA rating.
Health-flagged SDWIS rows in San Mateo include CITY OF REDWOOD CITY; MID-PENINSULA WATER DISTRICT; MENLO PARK MUNICIPAL WATER, while Csbio leads reported TRI pounds among local Form R filers. AQS median AQI 27 / peak 73 in 2024.
Burden score 39/100 (Moderate Risk) is the only weighted composite on this page. The tables below list every TRI facility, SDWIS system, and Superfund site EPA has on record for San Mateo -- not just the names called out above -- reproducing the disclosure history as filed, not a current-safety verdict. Extract current as of 2026-08-25.
Release-over-release change
What changed for San Mateo, CA: EPA TRI 2023 reporting year
Same facilities, both years
+30.2%
8 facilities that filed in 2022 and 2023
Whole inventory
+30.2%
509 lb → 663 lb, every facility that filed
Between the two reporting years, 1 facility filed for the first time and 0 stopped filing. Facilities entering or leaving the inventory are excluded from the same-facility comparison above.
- San Mateo, CA's total reported releases rose from 509 lb in 2022 to 663 lb in 2023, based on EPA TRI filings.
- San Mateo, CA's land releases rose from 7 lb in 2022 to 180 lb in 2023, based on EPA TRI filings.
Air Quality History (2020–2024)
EPA Air Quality Index (AQI) data showing how many days per year fall into each air quality category.
| Year | Good | Moderate | Unhealthy (SG) | Max AQI |
|---|---|---|---|---|
| 2024 | 281 (88%) | 38 | 0 | 73 |
| 2023 | 355 (98%) | 8 | 0 | 71 |
| 2022 | 267 (73%) | 98 | 0 | 85 |
| 2021 | 290 (79%) | 75 | 0 | 90 |
| 2020 | 257 (70%) | 99 | 5 | 199 |
Source: EPA Air Quality System (AQS) Annual AQI by County AQI categories: Good (0-50), Moderate (51-100), Unhealthy for Sensitive Groups (101-150), Unhealthy (151-200), Very Unhealthy (201-300), Hazardous (301+)
For real-time air quality readings and pollutant breakdowns in California, see the EPA's AirNow.gov.
Water Systems (41)
| System | System pop (SDWIS) | Violations |
|---|---|---|
| SFPUC CITY DISTRIBUTION DIVISION | 848,019 | 0 |
| CITY OF DALY CITY | 104,901 | 0 |
| CITY OF REDWOOD CITY | 92,819 | 3 |
| CITY OF SAN BRUNO | 42,631 | 0 |
| NORTH COAST COUNTY WATER DIST | 38,546 | 0 |
| ESTERO MUNICIPAL IMPROVEMENT DISTRICT | 36,556 | 0 |
| CITY OF BURLINGAME | 31,451 | 0 |
| MID-PENINSULA WATER DISTRICT | 30,609 | 2 |
| CITY OF MILLBRAE | 22,795 | 0 |
| MENLO PARK MUNICIPAL WATER | 22,362 | 2 |
| COASTSIDE COUNTY WATER DISTRICT | 18,940 | 0 |
| WESTBOROUGH WATER DISTRICT | 13,486 | 0 |
| TOWN OF HILLSBOROUGH | 11,766 | 0 |
| MONTARA WATER AND SANITARY DISTRICT | 6,078 | 0 |
| TREASURE ISLAND | 3,864 | 0 |
| CITY OF BRISBANE | 3,402 | 3 |
| GUADALUPE VALLEY MID | 1,472 | 0 |
| CUESTA LA HONDA GUILD INC | 915 | 8 |
| COUNTY SERVICE AREA 11 | 642 | 2 |
| SAN FRANCISCO REGIONAL WATER SYSTEM | 600 | 0 |
| HHW&P MOCCASIN COMPOUND-SFPUC | 410 | 0 |
| CAMP JONES GULCH | 357 | 0 |
| COUNTY SERVICE AREA 7 | 300 | 7 |
| TOWN OF SUNOL - SFPUC | 281 | 0 |
| IL VINETO | 160 | 0 |
| BUTANO CANYON MUTUAL | 150 | 0 |
| LAZY B MOBILEHOME PARK | 125 | 6 |
| REDWOOD GLEN CAMP & CONFERENCE CTR | 114 | 0 |
| PORTOLA IMPROVEMENT ASSOCIATION MWC | 90 | 0 |
| MOUNTAIN VIEW MOBILE HOME PARK | 75 | 9 |
| LOMA MAR MUTUAL | 65 | 6 |
| BIANCHI FLOWERS INC | 65 | 2 |
| REDWOOD TERRACE MUTUAL | 56 | 1 |
| MARCHI CENTRAL FARM | 50 | 4 |
| HUNTER'S FISHING RESORT | 50 | 1 |
| SHIRK MOBILE HOME PARK | 39 | 8 |
| OKU INCORPORATED | 35 | 4 |
| BLUE LAKES MOBILE HOME PARK | 32 | 1 |
| PUENTE HOUSING SOLUTIONS | 28 | 1 |
| SFPUC-PLEASANTON WELLS | 1 | 0 |
| THOMAS SHAFT WHOLESALE | 1 | 0 |
TRI Facilities (14)
| # | Facility | Total Releases |
|---|---|---|
| 1 | Csbio | 230.1K lbs |
| 2 | Nxedge San Carlos | 20.7K lbs |
| 3 | US Doe Slac National Accelerator Laboratory | 4.7K lbs |
| 4 | Chemelex LLC | 2.4K lbs |
| 5 | Central Concrete Supply Co. Inc. - South San Francisco | 80 lbs |
| 6 | Central Concrete Supply Co Inc - Redwood City | 40 lbs |
| 7 | Granite Rock Co Redwood City | 15 lbs |
| 8 | Univar Solutions USA | 12 lbs |
| 9 | Harbor Ready Mix | 4 lbs |
| 10 | Harbor Ready Mix - Redwood City | 1 lbs |
| 11 | Te Connectivy Inc. | 0 lbs |
| 12 | Cemex San Carlos | 0 lbs |
| 13 | Vivion Inc | 0 lbs |
| 14 | Garratt-Callahan Co Burlingame | 0 lbs |
Cities in San Mateo (19)
Frequently Asked Questions
What is the environmental risk level in San Mateo, California? ▼
Are there Superfund sites in San Mateo? ▼
How many toxic release facilities are in San Mateo? ▼
What is the air quality in San Mateo? ▼
Is the drinking water safe in San Mateo? ▼
What environmental agencies cover San Mateo? ▼
What does this county environmental profile show?
This county environmental profile rolls up EPA Toxics Release Inventory facility reports, Safe Drinking Water Information System public-water-system filings, and Superfund National Priorities List sites for the county boundary defined by the U.S. Census Bureau. Facility counts reflect facilities with a reporting address inside the county, not where downstream environmental effects may be observed. Population figures are from the most recent Census ACS 5-year estimate. The county detail page is updated whenever the upstream EPA programs publish revised data; see the methodology page for the documented ingest cadence and the editorial choices governing how aggregations are computed.
Read our methodology - how this data is sourced, computed, and verified.