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Steel Dynamics Southwest LLC

Blast Furnaces And Steel Mills, Sinton, Texas. NPDES permit TX0139629 expired May 26, 2026; its limits still apply. Last 12 months: over a limit 9 times (last August 2026). Source: EPA ECHO, Oct 22, 2026.

Reports due
About 20 days after each period: outfall 001 form A monthly (8 values), outfall 002 form A monthly (7 values), outfall 003 form A monthly (7 values), outfall 004 form A monthly (7 values), outfall 101 form A monthly (22 values), outfall 201 form A monthly (18 values), and 2 more forms
Last report on file
August 2026
Oct 2024 – Sep 2025
36 values over a limit, 0 required values missing, 0 of 78 reports late

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

Period endingOutfallParameterReportedLimitOver by
October 2025201Solids, total suspended, daily maximum31.79 lb/d≤ 21.97 lb/d45%
November 2025201Solids, total suspended, daily average21.23 lb/d≤ 17.52 lb/d21%
November 2025201Solids, total suspended, daily maximum45.6 lb/d≤ 21.97 lb/d108%
December 2025001Nitrogen, ammonia total [as N], daily average3.1 mg/L≤ 3 mg/L3%
December 2025201Solids, total suspended, daily maximum33.19 lb/d≤ 21.97 lb/d51%
April 2026201Solids, total suspended, daily average19.98 lb/d≤ 17.52 lb/d14%
April 2026201Solids, total suspended, daily maximum38.48 lb/d≤ 21.97 lb/d75%
August 2026201Oil & Grease, daily average43.52 lb/d≤ 14.62 lb/d198%
August 2026201Oil & Grease, daily maximum169.11 lb/d≤ 14.71 lb/d1050%

Limits in force (101)

ParameterStatisticLimitMonthsOutfall
Temperature, water deg. fahrenheitdaily maximumreport only (deg F)all year001
Oxygen, dissolved [DO]monthly minimum≥ 3 mg/Lall year001
Nitrogen, ammonia total [as N]daily average≤ 3 mg/Lall year001
Nitrogen, ammonia total [as N]daily maximumreport only (mg/L)all year001
Flow, in conduit or thru treatment plantdaily averagereport only (MGD)all year001
Flow, in conduit or thru treatment plantdaily maximumreport only (MGD)all year001
BOD, carbonaceous [5 day, 20 C]daily average≤ 45 mg/Lall year001
BOD, carbonaceous [5 day, 20 C]daily maximumreport only (mg/L)all year001
pHminimum≥ 6 SUall year002
pHmaximum≤ 9 SUall year002
Solids, total suspendeddaily maximum≤ 100 mg/Lall year002
Oil & Greasedaily maximum≤ 15 mg/Lall year002
Carbon, tot organic [TOC]daily maximum≤ 75 mg/Lall year002
Flow, in conduit or thru treatment plantdaily averagereport only (MGD)all year002
Flow, in conduit or thru treatment plantdaily maximumreport only (MGD)all year002
pHminimum≥ 6 SUall year003
pHmaximum≤ 9 SUall year003
Solids, total suspendeddaily maximum≤ 100 mg/Lall year003
Oil & Greasedaily maximum≤ 15 mg/Lall year003
Carbon, tot organic [TOC]daily maximum≤ 75 mg/Lall year003
Flow, in conduit or thru treatment plantdaily averagereport only (MGD)all year003
Flow, in conduit or thru treatment plantdaily maximumreport only (MGD)all year003
pHminimum≥ 6 SUall year004
pHmaximum≤ 9 SUall year004
Solids, total suspendeddaily maximum≤ 100 mg/Lall year004
Oil & Greasedaily maximum≤ 15 mg/Lall year004
Carbon, tot organic [TOC]daily maximum≤ 75 mg/Lall year004
Flow, in conduit or thru treatment plantdaily averagereport only (MGD)all year004
Flow, in conduit or thru treatment plantdaily maximumreport only (MGD)all year004
Temperature, water deg. fahrenheitdaily averagereport only (deg F)all year101
Temperature, water deg. fahrenheitdaily maximumreport only (deg F)all year101
pHminimum≥ 5 SUall year101
pHmaximum≤ 11 SUall year101
Solids, total suspendeddaily average≤ 764 lb/dall year101
Solids, total suspendeddaily maximum≤ 1885 lb/dall year101
Oil & Greasedaily average≤ 173 lb/dall year101
Oil & Greasedaily maximum≤ 617 lb/dall year101
Chromium, total [as Cr]daily average≤ 2.823 lb/dall year101
Chromium, total [as Cr]daily maximum≤ 7.042 lb/dall year101
Lead, total [as Pb]daily average≤ .386 lb/dall year101
Lead, total [as Pb]daily maximum≤ .815 lb/dall year101
Nickel, total [as Ni]daily average≤ 1.94 lb/dall year101
Nickel, total [as Ni]daily maximum≤ 5.77 lb/dall year101
Zinc, total [as Zn]daily average≤ 2.4 lb/dall year101
Zinc, total [as Zn]daily maximum≤ 7.04 lb/dall year101
Tetrachloroethylenedaily maximum≤ .976 lb/dall year101
Naphthalenedaily maximum≤ .649 lb/dall year101
Flow, in conduit or thru treatment plantdaily average≤ 1.2 MGDall year101
Flow, in conduit or thru treatment plantdaily maximum≤ 3 MGDall year101
pH range excursions, > 60 minutesmonthly total≤ 0 occur/moall year101
pH range excursions, monthly total accummonthly total≤ 446 minall year101
pHminimum≥ 7.5 SUall year201
pHmaximum≤ 10 SUall year201
Solids, total suspendeddaily average≤ 17.52 lb/dall year201
Solids, total suspendeddaily maximum≤ 21.97 lb/dall year201
Oil & Greasedaily average≤ 14.62 lb/dall year201
Oil & Greasedaily maximum≤ 14.71 lb/dall year201
Cyanide, total [as CN]daily average≤ .119 lb/dall year201
Cyanide, total [as CN]daily maximum≤ .256 lb/dall year201
Chromium, total [as Cr]daily average≤ .228 lb/dall year201
Chromium, total [as Cr]daily maximum≤ .552 lb/dall year201
Copper, total [as Cu]daily average≤ .483 lb/dall year201
Copper, total [as Cu]daily maximum≤ 1.011 lb/dall year201
Iron, total [as Fe]daily average≤ .931 lb/dall year201
Iron, total [as Fe]daily maximum≤ 1.903 lb/dall year201
Zinc, total [as Zn]daily average≤ .617 lb/dall year201
Zinc, total [as Zn]daily maximum≤ 1.583 lb/dall year201
Flow, in conduit or thru treatment plantdaily averagereport only (MGD)all year201
Flow, in conduit or thru treatment plantdaily maximumreport only (MGD)all year201
Whole effluent toxicity - retest #17-day minimumreport only (pass=0;fail=1)all yearTX1
Whole effluent toxicity - retest #1monthly average minimumreport only (pass=0;fail=1)all yearTX1
Whole effluent toxicity - retest #27-day minimumreport only (pass=0;fail=1)all yearTX1
Whole effluent toxicity - retest #2monthly average minimumreport only (pass=0;fail=1)all yearTX1
Low Flow Pass/Fail Survival Test Static Renewal 7 Day Chronic Ceriodaphnia dubia7-day minimumreport only (pass=0;fail=1)all yearTX1
Low Flow Pass/Fail Survival Test Static Renewal 7 Day Chronic Ceriodaphnia dubiamonthly average minimumreport only (pass=0;fail=1)all yearTX1
Low Flow Pass/Fail Survival Test Static Renewal 7 Day Chronic Pimephales promelas7-day minimumreport only (pass=0;fail=1)all yearTX1
Low Flow Pass/Fail Survival Test Static Renewal 7 Day Chronic Pimephales promelasmonthly average minimumreport only (pass=0;fail=1)all yearTX1
NOEC Lethal Static Renewal 7 Day Chronic Ceriodaphnia dubia7-day minimumreport only (%)all yearTX1
NOEC Lethal Static Renewal 7 Day Chronic Ceriodaphnia dubiamonthly average minimumreport only (%)all yearTX1
NOEC Lethal Static Renewal 7 Day Chronic Pimephales promelas7-day minimumreport only (%)all yearTX1
NOEC Lethal Static Renewal 7 Day Chronic Pimephales promelasmonthly average minimumreport only (%)all yearTX1
NOEC Sub-Lethal Static Renewal 7 Day Chronic Ceriodaphnia dubia7-day minimumreport only (%)all yearTX1
NOEC Sub-Lethal Static Renewal 7 Day Chronic Ceriodaphnia dubiamonthly average minimumreport only (%)all yearTX1
NOEC Sub-Lethal Static Renewal 7 Day Chronic Pimephales promelas7-day minimumreport only (%)all yearTX1
NOEC Sub-Lethal Static Renewal 7 Day Chronic Pimephales promelasmonthly average minimumreport only (%)all yearTX1
Pass/Fail Sub-Lethal Static Renewal 7 Day Chronic Ceriodaphnia dubia7-day minimumreport only (pass=0;fail=1)all yearTX1
Pass/Fail Sub-Lethal Static Renewal 7 Day Chronic Ceriodaphnia dubiamonthly average minimumreport only (pass=0;fail=1)all yearTX1
Pass/Fail Sub-Lethal Static Renewal 7 Day Chronic Pinephales promelas7-day minimumreport only (pass=0;fail=1)all yearTX1
Pass/Fail Sub-Lethal Static Renewal 7 Day Chronic Pinephales promelasmonthly average minimumreport only (pass=0;fail=1)all yearTX1
LOEC Lethal Survival Static Renewal 7 Day Chronic Ceriodaphnia dubia7-day minimumreport only (%)all yearTX1
LOEC Lethal Survival Static Renewal 7 Day Chronic Ceriodaphnia dubiamonthly average minimumreport only (%)all yearTX1
LOEC Lethal Survival Static Renewal 7 Day Chronic Pimephales promelas7-day minimumreport only (%)all yearTX1
LOEC Lethal Survival Static Renewal 7 Day Chronic Pimephales promelasmonthly average minimumreport only (%)all yearTX1
LOEC Sub-Lethal Reproduction Static Renewal 7 Day Chronic Ceriodaphnia dubia7-day minimumreport only (%)all yearTX1
LOEC Sub-Lethal Reproduction Static Renewal 7 Day Chronic Ceriodaphnia dubiamonthly average minimumreport only (%)all yearTX1
LOEC Sub-Lethal Reproduction Static Renewal 7 Day Chronic Pimephales promelas7-day minimumreport only (%)all yearTX1
LOEC Sub-Lethal Reproduction Static Renewal 7 Day Chronic Pimephales promelasmonthly average minimumreport only (%)all yearTX1
Whole effluent toxicity - retest #1single samplereport only (pass=0;fail=1)all yearTXA
Whole effluent toxicity - retest #2single samplereport only (pass=0;fail=1)all yearTXA
LC50 Pass/Fail Static 24Hr Acute D. Pulexsingle samplereport only (pass=0;fail=1)all yearTXA
LC50 Pass/Fail Static 24Hr Acute Pimephales promelassingle samplereport only (pass=0;fail=1)all yearTXA

How strict are these limits?

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

Same industry: the 13 Primary Metal Industries permits in Texas.

Check this month's numbers Email me before each report is due

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On EPA ECHO: Facility report · DMR history

Your permit document is the final word. As JSON: /api/v1/permits/TX0139629 · MCP: https://passage-data.com/mcp