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City of Dillon

Sewage treatment plant, Dillon, Montana. NPDES permit MT0021458 expired Jun 30, 2022; its limits still apply. Last 12 months: no values over a limit, 8 of 22 reports late. Source: EPA ECHO, Oct 22, 2026.

Reports due
About 28 days after each period: form A monthly (32 values), form UP monthly (4 values)
Last report on file
August 2026
Oct 2024 – Sep 2025
0 values over a limit, 0 required values missing, 0 of 24 reports late

Limits in force (39)

ParameterStatisticLimitMonths
Temperature, water deg. centigrademonthly averagereport only (deg C)all year
Temperature, water deg. centigradeweekly maximumreport only (deg C)all year
Temperature, water deg. centigrademonthly averagereport only (deg C)all year
Flow ratemonthly averagereport only (MGD)all year
pHdaily minimum≥ 6 SUall year
pHdaily maximum≤ 9 SUall year
pHminimumreport only (SU)all year
pHmaximumreport only (SU)all year
Solids, total suspendedmonthly average≤ 30 mg/Lall year
Solids, total suspendedmaximum weekly average≤ 45 mg/Lall year
Solids, total suspendedmonthly average≤ 188 lb/dall year
Solids, total suspendedmaximum weekly average≤ 281 lb/dall year
Solids, total suspendedmonthly averagereport only (mg/L)all year
Solids, total suspendedmonthly averagereport only (lb/d)all year
Oil and grease, hexane extr methodmonthly maximum≤ 10 mg/LJun, Dec
Nitrogen, total [as N]monthly averagereport only (mg/L)Jun–Sep
Nitrogen, total [as N]maximum weekly averagereport only (mg/L)Jun–Sep
Nitrogen, total [as N]monthly average≤ 145.4 lb/dJun–Sep
Nitrogen, total [as N]maximum weekly averagereport only (lb/d)Jun–Sep
Nitrogen, ammonia total [as N]monthly averagereport only (mg/L)all year
Nitrogen, ammonia total [as N]daily maximumreport only (mg/L)all year
Nitrogen, ammonia total [as N]daily maximumreport only (mg/L)Mar, Jun, Sep, Dec
Nitrogen, Kjeldahl, total [as N]monthly averagereport only (mg/L)all year
Nitrite + Nitrate total [as N]monthly averagereport only (mg/L)all year
Phosphorus, total [as P]monthly averagereport only (mg/L)Jun–Sep
Phosphorus, total [as P]monthly average≤ 19.4 lb/dJun–Sep
E. coli, MTEC-MFmonthly geometric mean≤ 630 CFU/100mLJan, Feb, Mar, Nov, Dec
E. coli, MTEC-MFmonthly geometric mean≤ 126 CFU/100mLApr–Oct
E. coli, MTEC-MFweekly maximum≤ 1260 CFU/100mLJan, Feb, Mar, Nov, Dec
E. coli, MTEC-MFweekly maximum≤ 252 CFU/100mLApr–Oct
BOD, carbonaceous [5 day, 20 C]monthly average≤ 25 mg/Lall year
BOD, carbonaceous [5 day, 20 C]maximum weekly average≤ 40 mg/Lall year
BOD, carbonaceous [5 day, 20 C]monthly average≤ 156 lb/dall year
BOD, carbonaceous [5 day, 20 C]maximum weekly average≤ 250 lb/dall year
BOD, carbonaceous [5 day, 20 C]monthly averagereport only (mg/L)all year
BOD, carbonaceous [5 day, 20 C]monthly averagereport only (lb/d)all year
BOD, carbonaceous, percent removalmonthly average minimum≥ 85 %all year
Solids, suspended percent removalmonthly average minimum≥ 85 %all year
Oil and grease visualvaluereport only (abst=0;prst=1)all year

How strict are these limits?

Cited limits by parameter: Montana'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/MT0021458 · MCP: https://passage-data.com/mcp