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Stillwater, City of

Sewage treatment plant, major discharger, Stillwater, Oklahoma. NPDES permit OK0027057, in force until Mar 31, 2028. Last 12 months: over a limit 3 times (last August 2026), 4 required values missing, 2 of 19 reports late. Source: EPA ECHO, Oct 22, 2026.

Reports due
About 50 days after each period: outfall 001 form A monthly (22 values), outfall TX1 form Q quarterly (19 values), outfall SLD form F yearly, outfall SLD form P yearly, outfall SLL form A yearly, outfall SLS form A yearly
Renewal application due
Oct 3, 2027 · 180 days before expiry; your permit may set another date
Last report on file
September 2026
Oct 2024 – Sep 2025
0 values over a limit, 0 required values missing, 4 of 20 reports late

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

Period endingParameterReportedLimitOver by
August 2026Nitrogen, ammonia total [as N], monthly average2.3 mg/L≤ 2 mg/L15%
August 2026Nitrogen, ammonia total [as N], weekly average4.9 mg/L≤ 3 mg/L63%
August 2026pH, minimum6.3 SU≥ 6.5 SU—

Limits in force (100)

ParameterStatisticLimitMonthsOutfall
Oxygen, dissolved [DO]minimum≥ 5 mg/Lall year001
pHminimum≥ 6.5 SUall year001
pHmaximum≤ 9 SUall year001
Solids, total suspendedmonthly average≤ 15 mg/Lall year001
Solids, total suspendedweekly average≤ 22.5 mg/Lall year001
Solids, total suspendedmonthly average≤ 1251 lb/dall year001
Nitrogen, ammonia total [as N]monthly average≤ 2 mg/LApr–Oct001
Nitrogen, ammonia total [as N]monthly average≤ 4 mg/LJan, Feb, Mar, Nov, Dec001
Nitrogen, ammonia total [as N]weekly average≤ 3 mg/LApr–Oct001
Nitrogen, ammonia total [as N]weekly average≤ 6 mg/LJan, Feb, Mar, Nov, Dec001
Nitrogen, ammonia total [as N]monthly average≤ 166.8 lb/dApr–Oct001
Nitrogen, ammonia total [as N]monthly average≤ 333.6 lb/dJan, Feb, Mar, Nov, Dec001
Arsenic, total [as As]monthly average≤ 180.14 ug/Lall year001
Arsenic, total [as As]daily maximum≤ 312.09 ug/Lall year001
Arsenic, total [as As]monthly average≤ 15.02 lb/dall year001
Selenium, total [as Se]monthly average≤ 4.74 ug/Lall year001
Selenium, total [as Se]daily maximum≤ 8.21 ug/Lall year001
Selenium, total [as Se]monthly average≤ .4 lb/dall 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
E. coligeometric mean≤ 126 CFU/100mLMay–Sep001
E. colidaily maximum≤ 406 CFU/100mLMay–Sep001
BOD, carbonaceous [5 day, 20 C]monthly average≤ 9 mg/LJan, Feb, Mar, Nov, Dec001
BOD, carbonaceous [5 day, 20 C]monthly average≤ 5 mg/LApr–Oct001
BOD, carbonaceous [5 day, 20 C]weekly average≤ 13.5 mg/LJan, Feb, Mar, Nov, Dec001
BOD, carbonaceous [5 day, 20 C]weekly average≤ 7.5 mg/LApr–Oct001
BOD, carbonaceous [5 day, 20 C]monthly average≤ 750.6 lb/dJan, Feb, Mar, Nov, Dec001
BOD, carbonaceous [5 day, 20 C]monthly average≤ 417 lb/dApr–Oct001
Toxicity characteristic leaching proceduremonthly average minimumreport only (pass=0;fail=1)all yearSLD
Ann. amt sludge disposed by other methodannual totalreport only (DMT/y)all yearSLD
Annual amt of sludge incineratedannual totalreport only (DMT/y)all yearSLD
Annual sludge production, totalannual totalreport only (DMT/y)all yearSLD
Annual amount of sludge land appliedannual totalreport only (DMT/y)all yearSLD
Annual amt. sludge disposed surface unitannual totalreport only (DMT/y)all yearSLD
Annual amt sludge disposed in landfillannual totalreport only (DMT/y)all yearSLD
Annual amt sludge transported interstateannual totalreport only (DMT/y)all yearSLD
Compliance w/part 258 sludge requirementvaluereport only (N=0;Y=1)all yearSLD
Arsenic, dry weightsingle samplereport only (mg/kg)all yearSLL
Arsenic, dry weightmaximum≤ 75 mg/kgall yearSLL
Arsenic, dry weightmaximum value≤ 41 kg/haall yearSLL
Selenium, dry weightsingle samplereport only (mg/kg)all yearSLL
Selenium, dry weightmaximum≤ 100 mg/kgall yearSLL
Selenium, dry weightmaximum value≤ 100 kg/haall yearSLL
Polychlorinated biphenyls [PCBs]annual maximum≤ 49.99 mg/kgall yearSLL
Copper, dry weightsingle samplereport only (mg/kg)all yearSLL
Copper, dry weightmaximum≤ 4300 mg/kgall yearSLL
Copper, dry weightmaximum value≤ 1500 kg/haall yearSLL
Cadmium, dry weightsingle samplereport only (mg/kg)all yearSLL
Cadmium, dry weightmaximum≤ 85 mg/kgall yearSLL
Cadmium, dry weightmaximum value≤ 39 kg/haall yearSLL
Annual whole sludge application ratemaximum valuereport only (met t/ha/yr)all yearSLL
Molybdenum, sludge, total, dry weight [as Mo]single samplereport only (mg/kg)all yearSLL
Molybdenum, sludge, total, dry weight [as Mo]maximum≤ 75 mg/kgall yearSLL
Molybdenum, sludge, total, dry weight [as Mo]maximum valuereport only (kg/ha)all yearSLL
Zinc, sludge, total, dry weight [as Zn]single samplereport only (mg/kg)all yearSLL
Zinc, sludge, total, dry weight [as Zn]maximum≤ 7500 mg/kgall yearSLL
Zinc, sludge, total, dry weight [as Zn]maximum value≤ 2800 kg/haall yearSLL
Lead, sludge, total, dry weight [as Pb]single samplereport only (mg/kg)all yearSLL
Lead, sludge, total, dry weight [as Pb]maximum≤ 840 mg/kgall yearSLL
Lead, sludge, total, dry weight [as Pb]maximum value≤ 300 kg/haall yearSLL
Nickel, sludge, total, dry weight [as Ni]single samplereport only (mg/kg)all yearSLL
Nickel, sludge, total, dry weight [as Ni]maximum≤ 420 mg/kgall yearSLL
Nickel, sludge, total, dry weight [as Ni]maximum value≤ 420 kg/haall yearSLL
Mercury, sludge, total, dry weight [as Hg]single samplereport only (mg/kg)all yearSLL
Mercury, sludge, total, dry weight [as Hg]maximum≤ 57 mg/kgall yearSLL
Mercury, sludge, total, dry weight [as Hg]maximum value≤ 17 kg/haall yearSLL
Pollutant table from 503.13valuereport only (table #)all yearSLL
Level of pathogen requirements achievedmaximum valuereport only (state class)all yearSLL
Description of pathogen option usedvaluereport only (alt #)all yearSLL
Vector attraction reduction alternative usedvaluereport only (alt #)all yearSLL
Arsenic, dry weightallowable concentrationreport only (mg/kg)all yearSLS
Arsenic, dry weightsingle samplereport only (mg/kg)all yearSLS
Unit w/liner/leachate collection systemvaluereport only (N=0;Y=1)all yearSLS
Unit boundary to property line distancevaluereport only (m)all yearSLS
Nickel, sludge, total, dry weight [as Ni]allowable concentrationreport only (mg/kg)all yearSLS
Nickel, sludge, total, dry weight [as Ni]single samplereport only (mg/kg)all yearSLS
Chromium, sludge, total, dry weight [as Cr]allowable concentrationreport only (mg/kg)all yearSLS
Chromium, sludge, total, dry weight [as Cr]single samplereport only (mg/kg)all yearSLS
Level of pathogen requirements achievedsingle samplereport only (state class)all yearSLS
Description of pathogen option usedvaluereport only (alt #)all yearSLS
Vector attraction reduction alternative usedvaluereport only (alt #)all yearSLS
pHdaily minimumreport only (SU)all yearTX1
pHdaily maximumreport only (SU)all yearTX1
Nitrogen, ammonia total [as N]daily minimumreport only (mg/L)all yearTX1
Nitrogen, ammonia total [as N]monthly averagereport only (mg/L)all yearTX1
Nitrogen, ammonia total [as N]daily maximumreport only (mg/L)all yearTX1
Whole Effluent Toxicity [WET] - C. dubia7-day minimum≥ 100 %all yearTX1
Whole Effluent Toxicity [WET] - P. promelas7-day minimum≥ 100 %all yearTX1
Pass/Fail Static Renewal 7 Day Chronic Ceriodaphnia dubia7-day minimumreport only (pass=0;fail=1)all yearTX1
Pass/Fail Static Renewal 7Day Chronic Pimephales promelas7-day minimumreport only (pass=0;fail=1)all yearTX1
%Mortality 7Day Chronic Ceriodaphnia dubia7-day minimumreport only (%)all yearTX1
%Mortality Static Renewal 7Day Chronic Pimephales Promelas7-day minimumreport only (%)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 Pimephales promelas7-day 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 Pimephales promelas7-day 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 Pimephales promelas7-day minimumreport only (%)all yearTX1
Coef Of Var Static Renewal 7Day Chronic Ceriodaphnia dubia7-day minimumreport only (%)all yearTX1
Coef Of Var Static Renewal 7Day Chronic Pimephales promelas7-day minimumreport only (%)all yearTX1

How strict are these limits?

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

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/OK0027057 · MCP: https://passage-data.com/mcp