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Silverton Town of

Sewage treatment plant, Silverton, Colorado. NPDES permit CO0020311 expired Jun 30, 2024; its limits still apply. Last 12 months: over a limit 3 times (last August 2026). Source: EPA ECHO, Oct 22, 2026.

Reports due
About 28 days after each period: outfall 001 form B monthly (21 values), outfall 001 form Q quarterly (14 values), outfall 300 form I monthly (10 values)
Last report on file
August 2026
Oct 2024 – Sep 2025
4 values over a limit, 0 required values missing, 0 of 28 reports late

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

Period endingParameterReportedLimitOver by
November 2025Chlorine, total residual, instantaneous maximum.69 mg/L≤ .5 mg/L38%
August 2026BOD, 5-day, 20 deg. C, 30-day average37.5 mg/L≤ 30 mg/L25%
August 2026pH, minimum4.62 SU≥ 6.5 SU—

Limits in force (72)

ParameterStatisticLimitMonthsOutfall
BOD, 5-day, 20 deg. C30-day average≤ 30 mg/Lall year001
BOD, 5-day, 20 deg. Cmaximum 7-day average≤ 45 mg/Lall year001
pHminimum≥ 6 SUJan001
pHminimum≥ 6 SUFeb001
pHminimum≥ 6.2 SUMar001
pHminimum≥ 6.5 SUApr001
pHminimum≥ 6.5 SUMay001
pHminimum≥ 6.5 SUJun001
pHminimum≥ 6.5 SUJul001
pHminimum≥ 6.5 SUAug001
pHminimum≥ 6.5 SUSep001
pHminimum≥ 6.5 SUOct001
pHminimum≥ 6.5 SUNov001
pHminimum≥ 6 SUDec001
pHmaximum≤ 9 SUJan001
pHmaximum≤ 9 SUFeb001
pHmaximum≤ 9 SUMar001
pHmaximum≤ 9 SUApr001
pHmaximum≤ 9 SUMay001
pHmaximum≤ 9 SUJun001
pHmaximum≤ 9 SUJul001
pHmaximum≤ 9 SUAug001
pHmaximum≤ 9 SUSep001
pHmaximum≤ 9 SUOct001
pHmaximum≤ 9 SUNov001
pHmaximum≤ 9 SUDec001
Solids, total suspended30-day average≤ 75 mg/Lall year001
Solids, total suspendedmaximum 7-day average≤ 110 mg/Lall year001
Nitrogen, ammonia total [as N]30-day average≤ 65 mg/Lall year001
Nitrogen, ammonia total [as N]daily maximum≤ 65 mg/Lall year001
Iron, total recoverable30-day averagereport only (ug/L)all year001
Iron, total recoverable30-day average≤ 1286 ug/LJul001
Iron, total recoverable30-day averagereport only (ug/L)Jan, Feb, Mar, Apr, May, Jun, Aug, Sep, Oct, Nov, Dec001
Iron, total recoverabledaily maximumreport only (ug/L)all year001
Aluminum, total recoverable30-day averagereport only (ug/L)all year001
Aluminum, total recoverabledaily maximumreport only (ug/L)all year001
Zinc, potentially dissolved30-day averagereport only (ug/L)all year001
Zinc, potentially dissolveddaily maximumreport only (ug/L)all year001
Copper, potentially dissolved30-day averagereport only (ug/L)all year001
Copper, potentially dissolveddaily maximumreport only (ug/L)all year001
Cadmium, potentially dissolvd30-day average≤ 1.1 ug/Lall year001
Cadmium, potentially dissolvddaily maximum≤ 3 ug/Lall year001
Lead, potentially dissolvd30-day averagereport only (ug/L)all year001
Lead, potentially dissolvd30-day averagereport only (ug/L)all year001
Lead, potentially dissolvd30-day average≤ 4.6 ug/Lall year001
Lead, potentially dissolvddaily maximumreport only (ug/L)all year001
Lead, potentially dissolvddaily maximumreport only (ug/L)all year001
Lead, potentially dissolvddaily maximumreport only (ug/L)all year001
Manganese, potentially dissolvd30-day averagereport only (ug/L)all year001
Manganese, potentially dissolvddaily maximumreport only (ug/L)all year001
Oil and greaseinstantaneous maximum≤ 10 mg/Lall year001
Flow, in conduit or thru treatment plant30-day average≤ .42 MGDall year001
Flow, in conduit or thru treatment plantdaily maximumreport only (MGD)all year001
Chlorine, total residualinstantaneous maximum≤ .5 mg/Lall year001
E. coli30-day geometric mean≤ 2000 #/100mLall year001
E. colimaximum 7-day geometric mean≤ 4000 #/100mLall year001
Solids, total dissolved30-day averagereport only (mg/L)all year001
Solids, total dissolveddaily maximumreport only (mg/L)all year001
Solids, total dissolved30-day averagereport only (mg/L)all year001
Solids, total dissolveddaily maximumreport only (mg/L)all year001
BOD, 5-day, percent removalmonthly average minimum≥ 85 %all year001
Oil and grease visualinstantaneous maximumreport only (abst=0;prst=1)all year001
Plant capacity fact. percent of capacity30-day averagereport only (%)all year300
Plant capacity fact. percent of capacity30-day averagereport only (%)all year300
BOD, 5-day, 20 deg. C30-day averagereport only (mg/L)all year300
BOD, 5-day, 20 deg. Cmaximum 7-day averagereport only (mg/L)all year300
BOD, 5-day, 20 deg. C30-day averagereport only (lb/d)all year300
BOD, 5-day, 20 deg. Cmaximum 7-day averagereport only (lb/d)all year300
Solids, total suspended30-day averagereport only (mg/L)all year300
Solids, total suspendedmaximum 7-day averagereport only (mg/L)all year300
Flow, in conduit or thru treatment plant30-day averagereport only (MGD)all year300
Flow, in conduit or thru treatment plantdaily maximumreport only (MGD)all year300

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

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On EPA ECHO: Facility report · DMR history

Your permit document is the final word. As JSON: /api/v1/permits/CO0020311 · MCP: https://passage-data.com/mcp