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Sewage treatment plant, major discharger, Spearfish, South Dakota. NPDES permit SD0020044 expired Sep 30, 2025; its limits still apply. Last 12 months: over a limit 2 times (last September 2026). Source: EPA ECHO, Oct 22, 2026.
| Period ending | Parameter | Reported | Limit | Over by |
|---|---|---|---|---|
| September 2026 | Toxicity [acute], Ceriodaphnia dubia, daily maximum | 2.12 toxic | < 1 toxic | 112% |
| September 2026 | Toxicity [chronic], Ceriodaphnia dubia, daily maximum | 2.12 tox chronic | < 1 tox chronic | 112% |
| Parameter | Statistic | Limit | Months | Outfall |
|---|---|---|---|---|
| Temperature, water deg. centigrade | 30-day average | report only (deg C) | all year | 001 |
| Temperature, water deg. centigrade | daily maximum | report only (deg C) | all year | 001 |
| Flow rate | 30-day average | report only (MGD) | all year | 001 |
| Flow rate | daily maximum | report only (MGD) | all year | 001 |
| Conductivity | 30-day average | report only (umho/cm) | all year | 001 |
| Conductivity | daily maximum | report only (umho/cm) | all year | 001 |
| Oxygen, dissolved [DO] | daily minimum | report only (mg/L) | all year | 001 |
| BOD, 5-day, 20 deg. C | 30-day average | ≤ 10 mg/L | all year | 001 |
| BOD, 5-day, 20 deg. C | daily maximum | ≤ 17.5 mg/L | all year | 001 |
| BOD, 5-day, 20 deg. C | 30-day average | report only (mg/L) | all year | 001 |
| pH | daily minimum | ≥ 6.5 SU | all year | 001 |
| pH | daily maximum | ≤ 8.8 SU | all year | 001 |
| Alkalinity, total [as CaCO3] | 30-day average | report only (mg/L) | all year | 001 |
| Alkalinity, total [as CaCO3] | daily maximum | report only (mg/L) | all year | 001 |
| Solids, total suspended | 30-day average | ≤ 10 mg/L | all year | 001 |
| Solids, total suspended | daily maximum | ≤ 17.5 mg/L | all year | 001 |
| Solids, total suspended | 30-day average | report only (mg/L) | all year | 001 |
| Oil and grease, hexane extr method | daily maximum | ≤ 10 mg/L | all year | 001 |
| Oil and grease, hexane extr method | daily maximum | ≤ 10 mg/L | all year | 001 |
| Nitrogen, total [as N] | 30-day average | report only (mg/L) | all year | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 3.5 mg/L | Apr | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 3.1 mg/L | Feb | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 3.1 mg/L | Jan | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 3.3 mg/L | Mar | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 3 mg/L | May | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 2.5 mg/L | Jun | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 2.1 mg/L | Jul | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 1.9 mg/L | Aug | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 2.4 mg/L | Sep | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 2.5 mg/L | Oct | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 3.2 mg/L | Nov | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 2.8 mg/L | Dec | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 9.3 mg/L | Apr | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 7.8 mg/L | Feb | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 7.8 mg/L | Jan | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 8.7 mg/L | Mar | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 8.1 mg/L | May | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 7.8 mg/L | Jun | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 7.8 mg/L | Jul | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 6.8 mg/L | Aug | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 8.1 mg/L | Sep | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 6.8 mg/L | Oct | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 8.1 mg/L | Nov | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 6.8 mg/L | Dec | 001 |
| Nitrogen, nitrate total [as N] | 30-day average | report only (mg/L) | all year | 001 |
| Nitrogen, nitrate total [as N] | daily maximum | report only (mg/L) | all year | 001 |
| Phosphorus, total [as P] | 30-day average | report only (mg/L) | all year | 001 |
| Cyanide, weak acid, dissociable | value | report only (ug/L) | all year | 001 |
| Cyanide, weak acid, dissociable | value | report only (ug/L) | all year | 001 |
| Cyanide, total [as CN] | value | report only (ug/L) | all year | 001 |
| Cyanide, total [as CN] | value | report only (ug/L) | all year | 001 |
| Hardness, total [as CaCO3] | value | report only (mg/L) | all year | 001 |
| Hardness, total [as CaCO3] | daily maximum | report only (mg/L) | all year | 001 |
| Arsenic, total recoverable | value | report only (ug/L) | all year | 001 |
| Arsenic, total recoverable | value | report only (ug/L) | all year | 001 |
| Selenium, total recoverable | value | report only (ug/L) | all year | 001 |
| Selenium, total recoverable | value | report only (ug/L) | all year | 001 |
| Thallium, total recoverable | value | report only (ug/L) | all year | 001 |
| Thallium, total recoverable | value | report only (ug/L) | all year | 001 |
| Beryllium, total recoverable [as Be] | value | report only (ug/L) | all year | 001 |
| Beryllium, total recoverable [as Be] | value | report only (ug/L) | all year | 001 |
| Nickel, total recoverable | value | report only (ug/L) | all year | 001 |
| Nickel, total recoverable | value | report only (ug/L) | all year | 001 |
| Silver total recoverable | 30-day average | report only (ug/L) | all year | 001 |
| Silver total recoverable | daily maximum | ≤ 7.06 ug/L | all year | 001 |
| Silver total recoverable | daily maximum | report only (ug/L) | all year | 001 |
| Zinc, total recoverable | value | report only (ug/L) | all year | 001 |
| Zinc, total recoverable | value | report only (ug/L) | all year | 001 |
| Aluminum, total recoverable | value | report only (ug/L) | all year | 001 |
| Aluminum, total recoverable | value | report only (ug/L) | all year | 001 |
| Cadmium, total recoverable | value | report only (ug/L) | all year | 001 |
| Cadmium, total recoverable | value | report only (ug/L) | all year | 001 |
| Lead, total recoverable | 30-day average | ≤ 5.16 ug/L | all year | 001 |
| Lead, total recoverable | daily maximum | report only (ug/L) | all year | 001 |
| Lead, total recoverable | daily maximum | report only (ug/L) | all year | 001 |
| Chromium, total recoverable | value | report only (ug/L) | all year | 001 |
| Chromium, total recoverable | value | report only (ug/L) | all year | 001 |
| Copper, total recoverable | value | report only (ug/L) | all year | 001 |
| Copper, total recoverable | value | report only (ug/L) | all year | 001 |
| Molybdenum, total recoverable | value | report only (ug/L) | all year | 001 |
| Molybdenum, total recoverable | value | report only (ug/L) | all year | 001 |
| Antimony, total recoverable | value | report only (ug/L) | all year | 001 |
| Antimony, total recoverable | value | report only (ug/L) | all year | 001 |
| Phenols | value | report only (ug/L) | all year | 001 |
| Phenols | value | report only (ug/L) | all year | 001 |
| E. coli, colony forming units [CFU] | 30-day geometric mean | ≤ 630 #/100mL | May–Sep | 001 |
| E. coli, colony forming units [CFU] | daily maximum | ≤ 1178 #/100mL | May–Sep | 001 |
| Toxicity [acute], Ceriodaphnia dubia | daily maximum | < 1 toxic | all year | 001 |
| Toxicity [chronic], Ceriodaphnia dubia | daily maximum | < 1 tox chronic | all year | 001 |
| Toxicity [acute], Pimephales promelas [Fathead Minnow] | daily maximum | < 1 toxic | all year | 001 |
| Toxicity [chronic], Pimephales promelas [Fathead Minnow] | daily maximum | < 1 tox chronic | all year | 001 |
| Mercury, total recoverable | 30-day average | ≤ .77 ug/L | all year | 001 |
| Mercury, total recoverable | daily maximum | ≤ 1.4 ug/L | all year | 001 |
| Mercury, total recoverable | daily maximum | report only (ug/L) | all year | 001 |
| BOD, carbonaceous [5 day, 20 C] | 30-day average | report only (mg/L) | all year | 001 |
| BOD, carbonaceous [5 day, 20 C] | daily maximum | report only (mg/L) | all year | 001 |
| BOD, 5-day, percent removal | monthly average minimum | ≥ 85 % | all year | 001 |
| Solids, suspended percent removal | monthly average minimum | ≥ 85 % | all year | 001 |
| Oil and grease visual | daily maximum | ≤ 0 N=0;Y=1 | all year | 001 |
| Temperature, water deg. centigrade | 30-day average | report only (deg C) | all year | 002 |
| Temperature, water deg. centigrade | daily maximum | report only (deg C) | all year | 002 |
| Flow rate | 30-day average | report only (MGD) | all year | 002 |
| Flow rate | daily maximum | report only (MGD) | all year | 002 |
| Conductivity | 30-day average | report only (umho/cm) | all year | 002 |
| Conductivity | daily maximum | report only (umho/cm) | all year | 002 |
| pH | daily minimum | report only (SU) | all year | 002 |
| pH | daily maximum | report only (SU) | all year | 002 |
| Nitrogen, ammonia total [as N] | 30-day average | report only (mg/L) | all year | 002 |
| Nitrogen, ammonia total [as N] | daily maximum | report only (mg/L) | all year | 002 |
| Nitrogen, nitrite total [as N] | 30-day average | report only (mg/L) | all year | 002 |
| Nitrogen, nitrite total [as N] | daily maximum | report only (mg/L) | all year | 002 |
| Nitrogen, nitrate total [as N] | 30-day average | report only (mg/L) | all year | 002 |
| Nitrogen, nitrate total [as N] | daily maximum | report only (mg/L) | all year | 002 |
| Nitrogen, Kjeldahl, total [as N] | 30-day geometric mean | report only (mg/L) | all year | 002 |
| Nitrogen, Kjeldahl, total [as N] | daily maximum | report only (mg/L) | all year | 002 |
| Phosphorus, total [as P] | 30-day average | report only (mg/L) | all year | 002 |
| Phosphorus, total [as P] | daily maximum | report only (mg/L) | all year | 002 |
| Sodium adsorption ratio | 30-day average | report only (Ratio) | all year | 002 |
| Sodium adsorption ratio | daily maximum | report only (Ratio) | all year | 002 |
| Chloride [as Cl] | 30-day average | report only (mg/L) | all year | 002 |
| Chloride [as Cl] | daily maximum | report only (mg/L) | all year | 002 |
| Sulfate, total [as SO4] | 30-day average | report only (mg/L) | all year | 002 |
| Sulfate, total [as SO4] | daily maximum | report only (mg/L) | all year | 002 |
| E. coli, colony forming units [CFU] | 30-day geometric mean | report only (#/100mL) | all year | 002 |
| E. coli, colony forming units [CFU] | daily maximum | report only (#/100mL) | all year | 002 |
| Flow, irrigation | monthly total | report only (Mgal/mo) | all year | 002 |
| Duration of Land Application | maximum 7-day average | report only (d) | all year | 002 |
| Solids, total dissolved | 30-day average | report only (mg/L) | all year | 002 |
| Solids, total dissolved | daily maximum | report only (mg/L) | all year | 002 |
Cited limits by parameter: South Dakota's rules and the federal ones.
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Your permit document is the final word. As JSON: /api/v1/permits/SD0020044 · MCP: https://passage-data.com/mcp