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Matheson Tri-Gas, Inc.

Industrial Gases, Westlake, Louisiana. NPDES permit LA0127094, in force until Dec 14, 2027. Last 12 months: over a limit 9 times (last September 2026). Source: EPA ECHO, Oct 22, 2026.

Reports due
About 28 days after each period: outfall 001 form A quarterly (22 values), outfall 001 form Q quarterly (10 values), outfall 002 form Q quarterly (8 values), outfall 003 form Q quarterly (8 values)
Renewal application due
Jun 17, 2027 · 180 days before expiry; your permit may set another date
Last report on file
September 2026
Oct 2024 – Sep 2025
6 values over a limit, 0 required values missing, 1 of 24 reports late

Last 12 months (Oct 1, 2025 – Sep 30, 2026)

Period endingParameterReportedLimitOver by
December 2025Cyanide, total [as CN], daily maximum≤ .0122 lb/d≤ .000568 lb/d2048%
December 2025Cyanide, total [as CN], monthly average≤ .00039 lb/d≤ .000239 lb/d63%
December 2025Phenolics, total recoverable, daily maximum.223 lb/d≤ .126 lb/d77%
March 2026Copper, total [as Cu], daily maximum.00343 lb/d≤ .0024 lb/d43%
March 2026Cyanide, total [as CN], daily maximum< .0122 lb/d≤ .000568 lb/d2048%
March 2026Cyanide, total [as CN], monthly average< .00039 lb/d≤ .000239 lb/d63%
June 2026Copper, total [as Cu], daily maximum.00852 lb/d≤ .0024 lb/d255%
June 2026Cyanide, total [as CN], daily maximum< .00132 lb/d≤ .000568 lb/d132%
September 2026Mercury, total [as Hg], daily maximum.000551 lb/d≤ .0000435 lb/d1167%

Limits in force (48)

ParameterStatisticLimitMonthsOutfall
Temperature, water deg. fahrenheitinstantaneous minimumreport only (deg F)all year001
Temperature, water deg. fahrenheitinstantaneous minimumreport only (deg F)all year001
Temperature, water deg. fahrenheitinstantaneous maximum≤ 99 deg Fall year001
Temperature, water deg. fahrenheitinstantaneous maximum≤ 99 deg Fall year001
pHinstantaneous minimum≥ 6 SUall year001
pHinstantaneous minimum≥ 6 SUall year001
pHinstantaneous maximum≤ 9 SUall year001
pHinstantaneous maximum≤ 9 SUall year001
Oil & Greasemonthly average< 10 mg/Lall year001
Oil & Greasemonthly average< 10 mg/Lall year001
Oil & Greasedaily maximum≤ 15 mg/Lall year001
Oil & Greasedaily maximum≤ 15 mg/Lall year001
Oil & Greasemonthly average≤ 11.36 lb/dall year001
Oil & Greasemonthly average≤ 11.36 lb/dall year001
Oil & Greasedaily maximum≤ 22.72 lb/dall year001
Oil & Greasedaily maximum≤ 22.72 lb/dall year001
Carbon, tot organic [TOC]daily maximum≤ 50 mg/Lall year001
Carbon, tot organic [TOC]daily maximum≤ 50 mg/Lall year001
Cyanide, total [as CN]monthly average≤ .000239 lb/dall year001
Cyanide, total [as CN]daily maximum≤ .000568 lb/dall year001
Copper, total [as Cu]monthly average≤ .001 lb/dall year001
Copper, total [as Cu]daily maximum≤ .0024 lb/dall year001
Lead, total [as Pb]monthly average≤ .016 lb/dall year001
Lead, total [as Pb]daily maximum≤ .038 lb/dall year001
Phenolics, total recoverablemonthly average≤ .053 lb/dall year001
Phenolics, total recoverabledaily maximum≤ .126 lb/dall year001
Flow, in conduit or thru treatment plantmonthly averagereport only (MGD)all year001
Flow, in conduit or thru treatment plantmonthly averagereport only (MGD)all year001
Flow, in conduit or thru treatment plantdaily maximumreport only (MGD)all year001
Flow, in conduit or thru treatment plantdaily maximumreport only (MGD)all year001
Mercury, total [as Hg]monthly average≤ .0000183 lb/dall year001
Mercury, total [as Hg]daily maximum≤ .0000435 lb/dall year001
pHinstantaneous minimum≥ 6 SUall year002
pHinstantaneous maximum≤ 9 SUall year002
Oil & Greasedaily maximum≤ 15 mg/Lall year002
Carbon, tot organic [TOC]daily maximum≤ 50 mg/Lall year002
Zinc, total [as Zn]monthly averagereport only (mg/L)all year002
Zinc, total [as Zn]daily maximumreport only (mg/L)all year002
Flow, in conduit or thru treatment plantmonthly averagereport only (MGD)all year002
Flow, in conduit or thru treatment plantdaily maximumreport only (MGD)all year002
pHinstantaneous minimum≥ 6 SUall year003
pHinstantaneous maximum≤ 9 SUall year003
Oil & Greasedaily maximum≤ 15 mg/Lall year003
Carbon, tot organic [TOC]daily maximum≤ 50 mg/Lall year003
Zinc, total [as Zn]monthly averagereport only (mg/L)all year003
Zinc, total [as Zn]daily maximumreport only (mg/L)all year003
Flow, in conduit or thru treatment plantmonthly averagereport only (MGD)all year003
Flow, in conduit or thru treatment plantdaily maximumreport only (MGD)all year003

How strict are these limits?

Cited limits by parameter: Louisiana's rules and the federal ones.

Same industry: the 130 Chemicals and Allied Products permits in Louisiana.

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Your permit document is the final word. As JSON: /api/v1/permits/LA0127094 · MCP: https://passage-data.com/mcp