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City of Wall Lake

Sewage treatment plant, Wall Lake, Iowa. NPDES permit IA0033065, in force until Jul 31, 2029. Last 12 months: over a limit 6 times (last June 2026), 1 of 12 reports late. Source: EPA ECHO, Oct 22, 2026.

Reports due: About 15 days after each period: form A monthly (10 values)
Last report on file: September 2026
Oct 2024 – Sep 2025: 6 values over a limit, 0 required values missing, 3 of 12 reports late

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

Period ending	Parameter	Reported	Limit	Over by
November 2025	BOD, carbonaceous [5 day, 20 C], 30-day average	29.2	≤ 25 mg/L	17%
April 2026	pH, daily maximum	9.01	≤ 9 SU	—
June 2026	BOD, carbonaceous [5 day, 20 C], 30-day average	40.6	≤ 25 mg/L	62%
June 2026	BOD, carbonaceous [5 day, 20 C], 7-day average	40.6	≤ 40 mg/L	2%
June 2026	Solids, total suspended, 30-day average	169	≤ 80 mg/L	111%
June 2026	Solids, total suspended, 7-day average	169	≤ 120 mg/L	41%

Limits in force (10)

Parameter	Statistic	Limit	Months
pH	daily minimum	≥ 6.5 SU	all year
pH	daily maximum	≤ 9 SU	all year
Solids, total suspended	30-day average	≤ 80 mg/L	all year
Solids, total suspended	7-day average	≤ 120 mg/L	all year
Chloride [as Cl]	30-day average	≤ 394 mg/L	all year
Chloride [as Cl]	daily maximum	≤ 630 mg/L	all year
Chloride [as Cl]	30-day average	≤ 3516 lb/d	all year
Chloride [as Cl]	daily maximum	≤ 5620 lb/d	all year
BOD, carbonaceous [5 day, 20 C]	30-day average	≤ 25 mg/L	all year
BOD, carbonaceous [5 day, 20 C]	7-day average	≤ 40 mg/L	all year

How strict are these limits?

pH, daily minimum at least 6.5 SU — stricter than 56% of 699 other minor POTWs in Iowa; 44% have the same limit
Chloride [as Cl], 30-day average 394 mg/L — stricter than 47% of 69 other minor POTWs in Iowa
Chloride [as Cl], daily maximum 630 mg/L — stricter than 40% of 69 other minor POTWs in Iowa; 6% have the same limit

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/IA0033065 · MCP: https://passage-data.com/mcp