Potosi-Tennyson Sewage Commission — NPDES permit WI0021547: limits, due date and EPA's record

Sewage treatment plant, Potosi, Wisconsin. NPDES permit WI0021547 expired Dec 31, 2023; its limits still apply. Last 12 months: over a limit once (last October 2025), 42 required values missing, 4 of 22 reports late. Source: EPA ECHO, Oct 22, 2026.

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

Period ending	Parameter	Reported	Limit	Over by
October 2025	Phosphorus, total [as P], monthly average	4.0053	≤ 2.8 mg/L	43%

Limits in force (19)

Parameter	Statistic	Limit	Months	Outfall
Oxygen, dissolved [DO]	daily minimum	≥ 4 mg/L	all year	001
BOD, 5-day, 20 deg. C	weekly average	≤ 30 mg/L	all year	001
BOD, 5-day, 20 deg. C	monthly average	≤ 20 mg/L	all year	001
pH	daily minimum	≥ 6 SU	all year	001
pH	daily maximum	≤ 9 SU	all year	001
Solids, total suspended	weekly average	≤ 30 mg/L	all year	001
Solids, total suspended	monthly average	≤ 20 mg/L	all year	001
Nitrogen, ammonia total [as N]	weekly average	≤ 35 mg/L	all year	001
Nitrogen, ammonia total [as N]	monthly average	≤ 15 mg/L	all year	001
Phosphorus, total [as P]	monthly average	≤ 2.8 mg/L	all year	001
Phosphorus, total [as P]	monthly average	report only (lb/d)	all year	001
Flow, in conduit or thru treatment plant	monthly average	report only (MGD)	all year	001
Flow, in conduit or thru treatment plant	daily maximum	report only (MGD)	all year	001
Coliform, fecal general	weekly geometric mean	≤ 656 #/100mL	May–Sep	001
Coliform, fecal general	geometric mean	≤ 400 #/100mL	May–Sep	001
BOD, 5-day, 20 deg. C	monthly average	report only (mg/L)	all year	701
BOD, 5-day, 20 deg. C	daily maximum	report only (mg/L)	all year	701
Solids, total suspended	monthly average	report only (mg/L)	all year	701
Solids, total suspended	daily maximum	report only (mg/L)	all year	701

How strict are these limits?

Your permit document is the final word. As JSON: /api/v1/permits/WI0021547 · MCP: https://passage-data.com/mcp