Pollution Analyst
How it works→
Superfund / NPL site · EPA Superfund SEMS through latest publishNPL FinalFEDERAL FACILITY

Longhorn Army Ammunition Plant

This site is currently on the EPA Superfund National Priorities List and remains under federal cleanup oversight. Most-cited contaminant of concern: Trichloroethene.

15600 Highway 134, Karnack, Texas · ZIP 75661 · EPA ID TX6213820529

See Harrison ContaminantsEquity contextHow we read Superfund data
CLEANUP TIMELINE

Listing-date and cleanup-phase enrichment from EPA's per-site SEMS profile is queued for a follow-up ingest pass. Until then, this section will populate from EPA's published timeline data.

Anomaly engine

Notable Signals

No notable signals at this Superfund site for the current ingest. Cleanup-phase and SEMS-action flags are deferred to a follow-up engineering pass.

Contaminants of concern · per EPA SEMS

What's In This Site

Each row pairs a contaminant with the medium it was found in (the exposure pathway). Hover any named contaminant for an agency-cited health-risk summary. Cited count = number of SEMS decision records (RODs and related) that name the pair.

ContaminantPathwayCited
TrichloroetheneHealth riskTCE. IARC Group 1 carcinogen — kidney cancer; suspected liver cancer and non-Hodgkin lymphoma. EPA MCL 5 µg/L; common DNAPL groundwater plume contaminant. (IARC, EPA, ATSDR)Groundwater14
Chloroethene (Vinyl Chloride)Health riskIARC Group 1 carcinogen — angiosarcoma of the liver. Final TCE/PCE biodegradation product; commonly found in groundwater plumes. EPA MCL 2 µg/L. (IARC, EPA)Groundwater11
PerchlorateHealth riskDisrupts thyroid iodide uptake — affects fetal development and infant cognition; rocket-fuel and explosives contaminant. EPA HRL 15 µg/L. (EPA, NRC)Groundwater11
Cis-1,2-DichloroetheneHealth riskTCE biodegradation intermediate. EPA MCL 70 µg/L; lower toxicity than parent solvents but commonly co-occurs in groundwater plumes. (EPA)Groundwater10
1,1-DichloroetheneHealth riskVinylidene chloride; IARC Group 3 (inadequate evidence in humans) but liver toxic in animal studies; common TCE/PCE biodegradation product. (IARC, EPA)Groundwater9
PerchlorateHealth riskDisrupts thyroid iodide uptake — affects fetal development and infant cognition; rocket-fuel and explosives contaminant. EPA HRL 15 µg/L. (EPA, NRC)Soil8
1,2-DichloroethaneHealth riskIARC Group 2B possible carcinogen; liver and kidney toxic. EPA MCL 5 µg/L. (IARC, EPA)Groundwater7
NickelHealth riskNickel compounds are IARC Group 1 carcinogens; inhalation exposure raises lung and nasal cancer risk. (IARC)Groundwater7
TetrachloroetheneHealth riskPCE / 'perc'. IARC Group 2A probable carcinogen; central-nervous-system effects; common dry-cleaning solvent and DNAPL plume contaminant. EPA MCL 5 µg/L. (IARC, EPA)Groundwater7
1,1,2-TrichloroethaneGroundwater6
ArsenicHealth riskIARC Group 1 carcinogen via inhalation and ingestion. EPA MCL 10 µg/L; chronic exposure causes skin, lung, bladder cancer and cardiovascular disease. (IARC, EPA, ATSDR)Groundwater6
ChromiumHealth riskHexavalent chromium (Cr-VI) is an IARC Group 1 carcinogen via inhalation, causing lung cancer; trivalent chromium is far less toxic. (IARC, EPA)Groundwater6
Dichloromethane (Methylene Chloride)Health riskIARC Group 2A probable carcinogen; central-nervous-system depressant; banned for most consumer paint-stripper uses. (IARC, EPA)Groundwater6
BariumHealth riskSoluble barium compounds are toxic if ingested, affecting the heart, kidneys, and nervous system. Insoluble forms (e.g. barium sulfate) are far less toxic. (EPA)Groundwater4
CadmiumGroundwater4
CobaltGroundwater4
ManganeseHealth riskExcess inhalation can cause manganism, a Parkinson-like neurological disorder. (ATSDR)Groundwater4
ThalliumGroundwater4
TrichloroetheneHealth riskTCE. IARC Group 1 carcinogen — kidney cancer; suspected liver cancer and non-Hodgkin lymphoma. EPA MCL 5 µg/L; common DNAPL groundwater plume contaminant. (IARC, EPA, ATSDR)Soil4
1,1,1-TrichloroethaneHealth riskMethyl chloroform. CNS depressant; ozone-depleting substance phased out under Montreal Protocol. EPA MCL 200 µg/L. (EPA, ATSDR)Groundwater3
1,3,5-TrinitrobenzeneGroundwater3
AntimonyHealth riskInhaled antimony trioxide is an IARC Group 2B possible carcinogen; respiratory and cardiovascular effects from long-term exposure. EPA MCL 6 µg/L. (IARC, EPA)Groundwater3
BenzeneHealth riskIARC Group 1 carcinogen. Long-term inhalation causes leukemia and bone-marrow disorders. (IARC, EPA)Groundwater3
Bis(2-Ethylhexyl)PhthalateGroundwater3
Dichloromethane (Methylene Chloride)Health riskIARC Group 2A probable carcinogen; central-nervous-system depressant; banned for most consumer paint-stripper uses. (IARC, EPA)Soil3
Trans-1,2-DichloroetheneHealth riskTCE biodegradation intermediate. EPA MCL 100 µg/L; lower toxicity than parent solvents but commonly co-occurs in groundwater plumes. (EPA)Groundwater3
1,1-DichloroethaneHealth riskSuspected carcinogen (EPA C/likely); CNS depressant. Common at solvent-contaminated sites as a degradation intermediate. (EPA, ATSDR)Groundwater2
1,4-DioxaneHealth riskIARC Group 2B possible carcinogen; persistent in groundwater, resists conventional treatment. EPA HRL 0.35 µg/L (10⁻⁶ cancer risk). (IARC, EPA)Groundwater2
2,4,6-TrinitrotolueneSoil2
2,4-DinitrotolueneGroundwater2

Showing the top 30 pairs by SEMS citation count. 72 additional (contaminant, pathway) pairs are recorded for this site.

Drinking-water linkage · SDWIS

No Groundwater PWSes Serving Communities Within 3 Miles

No SDWIS public water systems drawing groundwater (or mixed sources) serve a community whose centroid sits within 3 miles of this site. Empty results are not a guarantee of non-impact — distance is computed to served-place centroids, and SDWIS does not expose individual wellhead locations.

Methodology: served-city centroid (TIGER 2020) is used as the PWS coordinate. Source-water classification from SDWIS primary_source_code; only groundwater and mixed-source systems are queried. Click any system above for its full SDWIS profile.

Equity context · ACS 2018-2022 block-group demographics

Who Lives Near This Site

Harrison County, Texas (no Census block groups within 1 mile and no host city — falling back to containing county): a population of 69,098. Why we surface this →

POPULATION SHARE
16.3%

Low-income

POPULATION SHARE
38.6%

People of color

POPULATION SHARE
6.9%

Under age 5

POPULATION SHARE
17.0%

Over age 64

Source: Census ACS 2018-2022 (5-year) + USEPA-clone EJ blockgroup stats (raw indicators + EJ disparity mirror). NPL site proximity contributes to the national EJ pattern; indicator-level percentile and disparity scores are surfaced on the county page and the state page.

Source. EPA Superfund Enterprise Management System (SEMS) · retrieved 2026-05-07. SEMS is a federal public-domain dataset under 17 USC §105.

What this is not. We report EPA's published Superfund record — site listing, status, and contaminants of concern as named in EPA's decision documents. We do not perform site visits, independent air or water sampling, or current-state health-risk assessment. NPL listing reflects EPA's Hazard Ranking Score at a point in time; it does not by itself describe present-day exposure.