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Twentymile Coal LLC

Bituminous Coal And Lignite - Surface, Oak Creek, Colorado. NPDES permit CO0036684 expired Apr 30, 2012; its limits still apply. Last 12 months: over a limit once (last December 2025). Source: EPA ECHO, Oct 22, 2026.

Reports due
About 28 days after each period: outfall 001 form A quarterly (26 values), outfall 001 form X quarterly (8 values), outfall 01Y form X quarterly (8 values), outfall MON form 1 quarterly (44 values)
Last report on file
June 2026
Oct 2024 – Sep 2025
0 values over a limit, 0 required values missing, 0 of 16 reports late

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

Period endingParameterReportedLimitOver by
December 2025Solids, settleable, daily maximum.53 mL/L≤ .5 mL/L6%

Limits in force (102)

ParameterStatisticLimitMonthsOutfall
pHminimum≥ 6.5 SUall year001
pHminimum≥ 6.5 SUall year001
pHmaximum≤ 9 SUall year001
pHmaximum≤ 9 SUall year001
Solids, total suspended30-day average≤ 35 mg/Lall year001
Solids, total suspended30-day average≤ 35 mg/Lall year001
Solids, total suspendeddaily maximum≤ 70 mg/Lall year001
Solids, total suspendeddaily maximum≤ 70 mg/Lall year001
Solids, settleable30-day averagereport only (mL/L)all year001
Solids, settleable30-day averagereport only (mL/L)all year001
Solids, settleabledaily maximum≤ .5 mL/Lall year001
Solids, settleabledaily maximum≤ .5 mL/Lall year001
Iron, total recoverable30-day average≤ 1000 ug/Lall year001
Iron, total recoverable30-day average≤ 1000 ug/Lall year001
Oil and greaseinstantaneous maximum≤ 10 mg/Lall year001
Oil and greaseinstantaneous maximum≤ 10 mg/Lall year001
Flow, in conduit or thru treatment plant30-day average≤ .46 MGDall year001
Flow, in conduit or thru treatment plant30-day average≤ .46 MGDall 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
Toxicity [chronic], Ceriodaphnia dubiaminimum valuereport only (tox chronic)all year001
Toxicity [chronic], Ceriodaphnia dubiamonthly average minimumreport only (tox chronic)all year001
Toxicity [chronic], Ceriodaphnia dubiaminimum valuereport only (tox chronic)all year001
Toxicity [chronic], Ceriodaphnia dubiaminimum valuereport only (tox chronic)all year001
Toxicity [chronic], Pimephales promelas [Fathead Minnow]monthly average minimumreport only (tox chronic)all year001
Toxicity [chronic], Pimephales promelas [Fathead Minnow]monthly average minimumreport only (tox chronic)all year001
Toxicity [chronic], Pimephales promelas [Fathead Minnow]minimum valuereport only (tox chronic)all year001
Toxicity [chronic], Pimephales promelas [Fathead Minnow]minimum valuereport only (tox chronic)all year001
Solids, total dissolvedquarterly averagereport only (mg/L)Mar, Jun, Sep, Dec001
Solids, total dissolvedquarterly averagereport only (mg/L)Mar, Jun, Sep, Dec001
Solids, total dissolveddaily maximumreport only (mg/L)Mar, Jun, Sep, Dec001
Solids, total dissolveddaily maximumreport only (mg/L)Mar, Jun, Sep, Dec001
Oil and grease visualinstantaneous maximumreport only (N=0;Y=1)all year001
Oil and grease visualinstantaneous maximumreport only (N=0;Y=1)all year001
%Effect Static Renewal 7 Day Chronic Ceriodaphnia dubiamonthly average minimumreport only (%)all year001
%Effect Static Renewal 7 Day Chronic Ceriodaphnia dubiamonthly average minimumreport only (%)all year001
%Effect Static Renewal 7 Day Chronic Ceriodaphnia dubiaminimum valuereport only (%)all year001
%Effect Static Renewal 7 Day Chronic Ceriodaphnia dubiaminimum valuereport only (%)all year001
%Effect Static Renewal 7Day Chronic Pimephales promelasmonthly average minimumreport only (%)all year001
%Effect Static Renewal 7Day Chronic Pimephales promelasmonthly average minimumreport only (%)all year001
%Effect Static Renewal 7Day Chronic Pimephales promelasminimum valuereport only (%)all year001
%Effect Static Renewal 7Day Chronic Pimephales promelasminimum valuereport only (%)all year001
Toxicity [chronic], Ceriodaphnia dubiamonthly average minimumreport only (tox chronic)all year01Y
Toxicity [chronic], Ceriodaphnia dubiamonthly average minimumreport only (tox chronic)all year01Y
Toxicity [chronic], Ceriodaphnia dubiaminimum valuereport only (tox chronic)all year01Y
Toxicity [chronic], Ceriodaphnia dubiaminimum valuereport only (tox chronic)all year01Y
Toxicity [chronic], Pimephales promelas [Fathead Minnow]monthly average minimumreport only (tox chronic)all year01Y
Toxicity [chronic], Pimephales promelas [Fathead Minnow]monthly average minimumreport only (tox chronic)all year01Y
Toxicity [chronic], Pimephales promelas [Fathead Minnow]minimum valuereport only (tox chronic)all year01Y
Toxicity [chronic], Pimephales promelas [Fathead Minnow]minimum valuereport only (tox chronic)all year01Y
%Effect Static Renewal 7 Day Chronic Ceriodaphnia dubiamonthly average minimumreport only (%)all year01Y
%Effect Static Renewal 7 Day Chronic Ceriodaphnia dubiamonthly average minimumreport only (%)all year01Y
%Effect Static Renewal 7 Day Chronic Ceriodaphnia dubiaminimum value≥ 100 %all year01Y
%Effect Static Renewal 7 Day Chronic Ceriodaphnia dubiamonthly average minimum≥ 100 %all year01Y
%Effect Static Renewal 7Day Chronic Pimephales promelasmonthly average minimumreport only (%)all year01Y
%Effect Static Renewal 7Day Chronic Pimephales promelasmonthly average minimumreport only (%)all year01Y
%Effect Static Renewal 7Day Chronic Pimephales promelasminimum value≥ 100 %all year01Y
%Effect Static Renewal 7Day Chronic Pimephales promelasminimum value≥ 100 %all year01Y
Arsenic, total [as As]30-day averagereport only (ug/L)all yearMON
Arsenic, total [as As]30-day averagereport only (ug/L)all yearMON
Arsenic, total [as As]daily maximumreport only (ug/L)all yearMON
Arsenic, total [as As]daily maximumreport only (ug/L)all yearMON
Zinc, potentially dissolved30-day averagereport only (ug/L)all yearMON
Zinc, potentially dissolved30-day averagereport only (ug/L)all yearMON
Zinc, potentially dissolveddaily maximumreport only (ug/L)all yearMON
Zinc, potentially dissolveddaily maximumreport only (ug/L)all yearMON
Silver, potentially dissolved30-day averagereport only (ug/L)all yearMON
Silver, potentially dissolved30-day averagereport only (ug/L)all yearMON
Silver, potentially dissolveddaily maximumreport only (ug/L)all yearMON
Silver, potentially dissolveddaily maximumreport only (ug/L)all yearMON
Copper, potentially dissolved30-day averagereport only (ug/L)all yearMON
Copper, potentially dissolved30-day averagereport only (ug/L)all yearMON
Copper, potentially dissolveddaily maximumreport only (ug/L)all yearMON
Copper, potentially dissolveddaily maximumreport only (ug/L)all yearMON
Cadmium, potentially dissolvd30-day averagereport only (ug/L)all yearMON
Cadmium, potentially dissolvd30-day averagereport only (ug/L)all yearMON
Cadmium, potentially dissolvddaily maximumreport only (ug/L)all yearMON
Cadmium, potentially dissolvddaily maximumreport only (ug/L)all yearMON
Chromium, trivalent, potentially dissolvd30-day averagereport only (ug/L)all yearMON
Chromium, trivalent, potentially dissolvd30-day averagereport only (ug/L)all yearMON
Chromium, trivalent, potentially dissolvddaily maximumreport only (ug/L)all yearMON
Chromium, trivalent, potentially dissolvddaily maximumreport only (ug/L)all yearMON
Lead, potentially dissolvd30-day averagereport only (ug/L)all yearMON
Lead, potentially dissolvd30-day averagereport only (ug/L)all yearMON
Lead, potentially dissolvddaily maximumreport only (ug/L)all yearMON
Lead, potentially dissolvddaily maximumreport only (ug/L)all yearMON
Manganese, potentially dissolvd30-day averagereport only (ug/L)all yearMON
Manganese, potentially dissolvd30-day averagereport only (ug/L)all yearMON
Manganese, potentially dissolvddaily maximumreport only (ug/L)all yearMON
Manganese, potentially dissolvddaily maximumreport only (ug/L)all yearMON
Nickel, potentially dissolvd30-day averagereport only (ug/L)all yearMON
Nickel, potentially dissolvd30-day averagereport only (ug/L)all yearMON
Nickel, potentially dissolvddaily maximumreport only (ug/L)all yearMON
Nickel, potentially dissolvddaily maximumreport only (ug/L)all yearMON
Selenium, potentially dissolvd30-day averagereport only (ug/L)all yearMON
Selenium, potentially dissolvd30-day averagereport only (ug/L)all yearMON
Selenium, potentially dissolvddaily maximumreport only (ug/L)all yearMON
Selenium, potentially dissolvddaily maximumreport only (ug/L)all yearMON
Mercury, total [as Hg]30-day averagereport only (ug/L)all yearMON
Mercury, total [as Hg]30-day averagereport only (ug/L)all yearMON
Mercury, total [as Hg]daily maximumreport only (ug/L)all yearMON
Mercury, total [as Hg]daily maximumreport only (ug/L)all yearMON

How strict are these limits?

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

Same industry: the 19 Coal Mining permits in Colorado.

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On EPA ECHO: Facility report · DMR history

Your permit document is the final word. As JSON: /api/v1/permits/CO0036684 · MCP: https://passage-data.com/mcp