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Sewage treatment plant, major discharger, Oskaloosa, Iowa. NPDES permit IA0038521 expired Mar 31, 2026; its limits still apply. Last 12 months: no values over a limit, 4 required values missing. Source: EPA ECHO, Oct 22, 2026.
| Parameter | Statistic | Limit | Months | Outfall |
|---|---|---|---|---|
| Oxygen, dissolved [DO] | daily minimum | ≥ 5.2 mg/L | all year | 001 |
| BOD, 5-day, 20 deg. C | 30-day average | report only (mg/L) | all year | 001 |
| BOD, 5-day, 20 deg. C | daily maximum | report only (mg/L) | all year | 001 |
| BOD, 5-day, 20 deg. C | 30-day average | report only (lb/d) | all year | 001 |
| BOD, 5-day, 20 deg. C | daily maximum | report only (lb/d) | all year | 001 |
| pH | daily minimum | ≥ 6.5 SU | all year | 001 |
| pH | daily maximum | ≤ 9 SU | all year | 001 |
| pH | 30-day average | report only (SU) | all year | 001 |
| pH | daily maximum | report only (SU) | all year | 001 |
| Solids, total suspended | 30-day average | ≤ 30 mg/L | all year | 001 |
| Solids, total suspended | 7-day average | ≤ 45 mg/L | all year | 001 |
| Solids, total suspended | 30-day average | ≤ 563 lb/d | all year | 001 |
| Solids, total suspended | 7-day average | ≤ 844 lb/d | all year | 001 |
| Solids, total suspended | 30-day average | report only (mg/L) | all year | 001 |
| Solids, total suspended | daily maximum | report only (mg/L) | all year | 001 |
| Solids, total suspended | 30-day average | report only (lb/d) | all year | 001 |
| Solids, total suspended | daily maximum | report only (lb/d) | all year | 001 |
| Nitrogen, total [as N] | 30-day average | report only (mg/L) | all year | 001 |
| Nitrogen, total [as N] | daily maximum | report only (mg/L) | all year | 001 |
| Nitrogen, total [as N] | 30-day average | report only (lb/d) | all year | 001 |
| Nitrogen, total [as N] | daily maximum | report only (lb/d) | all year | 001 |
| Nitrogen, total [as N] | 30-day average | report only (mg/L) | all year | 001 |
| Nitrogen, total [as N] | daily maximum | report only (mg/L) | all year | 001 |
| Nitrogen, total [as N] | 30-day average | report only (lb/d) | all year | 001 |
| Nitrogen, total [as N] | daily maximum | report only (lb/d) | all year | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 2.5 mg/L | Dec | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 2.3 mg/L | Nov | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 4 mg/L | Feb | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 1.5 mg/L | Apr | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 1.3 mg/L | Jun | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 1.7 mg/L | May | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 3.4 mg/L | Mar | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 1 mg/L | Jul | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 1 mg/L | Aug | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 1.1 mg/L | Sep | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 1.6 mg/L | Oct | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 3.4 mg/L | Jan | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 10 mg/L | Dec | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 9.1 mg/L | Nov | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 14.2 mg/L | Feb | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 8.8 mg/L | Apr | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 6.4 mg/L | Jun | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 8.8 mg/L | May | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 12 mg/L | Mar | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 4.2 mg/L | Jul | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 4.8 mg/L | Aug | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 5.8 mg/L | Sep | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 10 mg/L | Oct | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 15 mg/L | Jan | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 46.4 lb/d | Dec | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 43.5 lb/d | Nov | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 74.2 lb/d | Feb | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 28.6 lb/d | Apr | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 24.6 lb/d | Jun | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 32.6 lb/d | May | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 63.9 lb/d | Mar | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 18.9 lb/d | Jul | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 17.9 lb/d | Aug | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 19.8 lb/d | Sep | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 29.2 lb/d | Oct | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | ≤ 63.9 lb/d | Jan | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 200 lb/d | Dec | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 171 lb/d | Nov | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 266.4 lb/d | Feb | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 165 lb/d | Apr | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 112.6 lb/d | Jun | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 165 lb/d | May | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 233 lb/d | Mar | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 73.2 lb/d | Jul | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 84.4 lb/d | Aug | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 103.2 lb/d | Sep | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 194 lb/d | Oct | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 277 lb/d | Jan | 001 |
| Nitrogen, Kjeldahl, total [as N] | 30-day average | report only (mg/L) | all year | 001 |
| Nitrogen, Kjeldahl, total [as N] | daily maximum | report only (mg/L) | all year | 001 |
| Nitrogen, Kjeldahl, total [as N] | 30-day average | report only (lb/d) | all year | 001 |
| Nitrogen, Kjeldahl, total [as N] | daily maximum | report only (lb/d) | all year | 001 |
| Phosphorus, total [as P] | 30-day average | report only (mg/L) | all year | 001 |
| Phosphorus, total [as P] | daily maximum | report only (mg/L) | all year | 001 |
| Phosphorus, total [as P] | 30-day average | report only (lb/d) | all year | 001 |
| Phosphorus, total [as P] | daily maximum | report only (lb/d) | all year | 001 |
| Phosphorus, total [as P] | 30-day average | report only (mg/L) | all year | 001 |
| Phosphorus, total [as P] | daily maximum | report only (mg/L) | all year | 001 |
| Phosphorus, total [as P] | 30-day average | report only (lb/d) | all year | 001 |
| Phosphorus, total [as P] | daily maximum | report only (lb/d) | all year | 001 |
| Toxicity [acute], Ceriodaphnia dubia | daily maximum | ≤ 1 N=0;Y=1 | all year | 001 |
| Toxicity [acute], Pimephales promelas [Fathead Minnow] | daily maximum | ≤ 1 N=0;Y=1 | all year | 001 |
| BOD, carbonaceous [5 day, 20 C] | 30-day average | ≤ 25 mg/L | all year | 001 |
| BOD, carbonaceous [5 day, 20 C] | 7-day average | ≤ 40 mg/L | all year | 001 |
| BOD, carbonaceous [5 day, 20 C] | 30-day average | ≤ 469 lb/d | all year | 001 |
| BOD, carbonaceous [5 day, 20 C] | 7-day average | ≤ 751 lb/d | all year | 001 |
| Nitrogen, total [as N] | 30-day average | report only (mg/L) | all year | 002 |
| Nitrogen, total [as N] | daily maximum | report only (mg/L) | all year | 002 |
| Nitrogen, total [as N] | 30-day average | report only (lb/d) | all year | 002 |
| Nitrogen, total [as N] | daily maximum | report only (lb/d) | 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 |
| Phosphorus, total [as P] | 30-day average | report only (lb/d) | all year | 002 |
| Phosphorus, total [as P] | daily maximum | report only (lb/d) | all year | 002 |
| Chlorine, total residual | daily minimum | ≥ .5 mg/L | all year | 002 |
Cited limits by parameter: Iowa'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/IA0038521 · MCP: https://passage-data.com/mcp