MATHESON TRI-GAS INC

NPDES permit TX0118745 · Minor NON-POTW · effective, expires 2027-02-08 · EPA's file as of 2026-09-19

Check this month's numbers before you file
Watch this permit — $79 a month. Every Monday, from EPA's newest files: the next report due and when, whether EPA's file holds your last one, any change to this permit's limits or status, and the renewal date.

EPA's record, 2025-09-01 to 2026-08-31

1values over a limit
0required values missing, on 0 form(s)
1of 11 forms filed late

Last period with anything received: 2026-07-31. Most often over: Sulfate (1).

Reporting

Reports are due about 25 days after each monitoring period ends (read off this permit's own late-day counts in EPA's filings).

Limits in force (19)

OutfallParameterStatisticLimitMonths
001Temperature, water deg. fahrenheitDAILY MX report only all year
001pHMINIMUM >= 6 SU all year
001pHMAXIMUM <= 9 SU all year
001Solids, total suspendedDAILY MX <= 100 mg/L all year
001Solids, total suspendedDAILY MX <= 33.36 lb/d all year
001Nitrogen, ammonia total [as N]DAILY MX <= 3.6 mg/L all year
001Selenium, total [as Se]DAILY AV <= .0168 mg/L all year
001Selenium, total [as Se]DAILY MX <= .0356 mg/L all year
001Flow, in conduit or thru treatment plantDAILY AV <= .04 MGD all year
001Flow, in conduit or thru treatment plantDAILY MX <= .05 MGD all year
001Chlorine, total residualDAILY AV <= .2 mg/L all year
001Chlorine, total residualDAILY MX <= .5 mg/L all year
001Chlorine, total residualDAILY AV <= .07 lb/d all year
001Chlorine, total residualDAILY MX <= .17 lb/d all year
001Solids, total dissolved [TDS]DAILY AV <= 4000 mg/L all year
001Solids, total dissolved [TDS]DAILY MX <= 8480 mg/L all year
001BOD, carbonaceous [5 day, 20 C]DAILY MX <= 88.5 mg/L all year
001SulfateDAILY AV <= 667 mg/L all year
001SulfateDAILY MX <= 1413 mg/L all year

Built from EPA's ECHO bulk files. EPA's file, not the permit document, is the source: read your permit. Check a report before you file it · All states