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Mammoth Spring, City of

Sewage treatment plant, Mammoth Spring, Arkansas. NPDES permit AR0023850, in force until Oct 31, 2028. Last 12 months: over a limit 34 times (last July 2026). Source: EPA ECHO, Oct 22, 2026.

Reports due
About 25 days after each period: form A monthly (21 values), form Q quarterly (6 values)
Renewal application due
May 4, 2028 · 180 days before expiry; your permit may set another date
Last report on file
August 2026
Oct 2024 – Sep 2025
8 values over a limit, 0 required values missing, 0 of 16 reports late

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

All 34 values over a limit
Period endingParameterReportedLimitOver by
January 2026Coliform, fecal general, 30-day geometric mean207 #/100mL≤ 200 #/100mL4%
January 2026Coliform, fecal general, 7-day geometric mean824 #/100mL≤ 400 #/100mL106%
February 2026Coliform, fecal general, 30-day geometric mean> 699 #/100mL≤ 200 #/100mL—
February 2026Coliform, fecal general, 7-day geometric mean> 2000 #/100mL≤ 400 #/100mL—
February 2026Nitrogen, ammonia total [as N], 7-day average12.2 mg/L≤ 10.3 mg/L18%
February 2026Nitrogen, ammonia total [as N], monthly average10.3 mg/L≤ 10 mg/L3%
February 2026Oxygen, dissolved [DO], instantaneous minimum7.15 mg/L≥ 7.4 mg/L3%
March 2026Coliform, fecal general, 7-day geometric mean440 #/100mL≤ 400 #/100mL10%
March 2026Nitrogen, ammonia total [as N], 7-day average13.5 mg/L≤ 10.3 mg/L31%
March 2026Nitrogen, ammonia total [as N], monthly average12.8 mg/L≤ 10 mg/L28%
March 2026Solids, total suspended, 7-day average30 mg/L≤ 23 mg/L30%
March 2026Solids, total suspended, monthly average18 mg/L≤ 15 mg/L20%
April 2026BOD, carbonaceous [5 day, 20 C], monthly average12.1 mg/L≤ 10 mg/L21%
April 2026Coliform, fecal general, 30-day geometric mean1116 #/100mL≤ 200 #/100mL458%
April 2026Coliform, fecal general, 7-day geometric mean1640 #/100mL≤ 400 #/100mL310%
April 2026Nitrogen, ammonia total [as N], 7-day average28.5 mg/L≤ 3.9 mg/L631%
April 2026Nitrogen, ammonia total [as N], monthly average19.2 mg/L≤ 3.9 mg/L392%
April 2026Nitrogen, ammonia total [as N], monthly average8.56 lb/d≤ 4.9 lb/d75%
April 2026Oxygen, dissolved [DO], instantaneous minimum6.69 mg/L≥ 7.4 mg/L10%
May 2026BOD, carbonaceous [5 day, 20 C], 7-day average22.6 mg/L≤ 15 mg/L51%
May 2026BOD, carbonaceous [5 day, 20 C], monthly average16.9 mg/L≤ 10 mg/L69%
May 2026Coliform, fecal general, 30-day geometric mean> 2000 #/100mL≤ 200 #/100mL—
May 2026Coliform, fecal general, 7-day geometric mean> 2000 #/100mL≤ 400 #/100mL—
May 2026Nitrogen, ammonia total [as N], 7-day average24.2 mg/L≤ 10.5 mg/L130%
May 2026Nitrogen, ammonia total [as N], monthly average22.1 mg/L≤ 7 mg/L216%
June 2026BOD, carbonaceous [5 day, 20 C], 7-day average15.8 mg/L≤ 15 mg/L5%
June 2026BOD, carbonaceous [5 day, 20 C], monthly average15.8 mg/L≤ 10 mg/L58%
June 2026Coliform, fecal general, 30-day geometric mean> 1876 #/100mL≤ 200 #/100mL—
June 2026Coliform, fecal general, 7-day geometric mean> 2000 #/100mL≤ 400 #/100mL—
June 2026Nitrogen, ammonia total [as N], 7-day average24.6 mg/L≤ 10.5 mg/L134%
June 2026Nitrogen, ammonia total [as N], monthly average23.6 mg/L≤ 7 mg/L237%
July 2026Coliform, fecal general, 7-day geometric mean510 #/100mL≤ 400 #/100mL28%
July 2026Nitrogen, ammonia total [as N], 7-day average13.9 mg/L≤ 10.5 mg/L32%
July 2026Nitrogen, ammonia total [as N], monthly average7.2 mg/L≤ 7 mg/L3%

Limits in force (34)

ParameterStatisticLimitMonths
Oxygen, dissolved [DO]instantaneous minimum≥ 7.4 mg/LJan, Feb, Mar, Apr, Nov, Dec
Oxygen, dissolved [DO]instantaneous minimum≥ 5 mg/LMay–Oct
pHminimum≥ 6 SUall year
pHmaximum≤ 9 SUall year
Solids, total suspendedmonthly average≤ 15 mg/Lall year
Solids, total suspended7-day average≤ 23 mg/Lall year
Solids, total suspendedmonthly average≤ 18.8 lb/dall year
Nitrogen, ammonia total [as N]monthly average≤ 7 mg/LMay–Oct
Nitrogen, ammonia total [as N]monthly average≤ 10 mg/LJan, Feb, Mar, Nov, Dec
Nitrogen, ammonia total [as N]monthly average≤ 3.9 mg/LApr
Nitrogen, ammonia total [as N]7-day average≤ 10.5 mg/LMay–Oct
Nitrogen, ammonia total [as N]7-day average≤ 10.3 mg/LJan, Feb, Mar, Nov, Dec
Nitrogen, ammonia total [as N]7-day average≤ 3.9 mg/LApr
Nitrogen, ammonia total [as N]monthly average≤ 8.8 lb/dMay–Oct
Nitrogen, ammonia total [as N]monthly average≤ 12.5 lb/dJan, Feb, Mar, Nov, Dec
Nitrogen, ammonia total [as N]monthly average≤ 4.9 lb/dApr
Nitrogen, Kjeldahl, total [as N]monthly averagereport only (mg/L)all year
Nitrogen, Kjeldahl, total [as N]7-day averagereport only (mg/L)all year
Nitrogen, Kjeldahl, total [as N]monthly averagereport only (lb/d)all year
Nitrite + Nitrate total [as N]monthly average≤ 10 mg/Lall year
Nitrite + Nitrate total [as N]7-day average≤ 10 mg/Lall year
Nitrite + Nitrate total [as N]monthly average≤ 12.5 lb/dall year
Phosphorus, total [as P]monthly averagereport only (mg/L)all year
Phosphorus, total [as P]7-day averagereport only (mg/L)all year
Phosphorus, total [as P]monthly averagereport only (lb/d)all year
Flow, in conduit or thru treatment plantmonthly averagereport only (MGD)all year
Flow, in conduit or thru treatment plantdaily maximumreport only (MGD)all year
Coliform, fecal general30-day geometric mean≤ 200 #/100mLall year
Coliform, fecal general7-day geometric mean≤ 400 #/100mLall year
Overflowsmonthly totalreport only (occur/mo)all year
Overflow volume [SS0 volume, CSO volume]monthly totalreport only (gal)all year
BOD, carbonaceous [5 day, 20 C]monthly average≤ 10 mg/Lall year
BOD, carbonaceous [5 day, 20 C]7-day average≤ 15 mg/Lall year
BOD, carbonaceous [5 day, 20 C]monthly average≤ 12.5 lb/dall year

How strict are these limits?

Cited limits by parameter: Arkansas'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/AR0023850 · MCP: https://passage-data.com/mcp