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Mattawoman WWTP

Sewage treatment plant, major discharger, Charles County, Maryland. NPDES permit MD0021865, in force until Jul 31, 2029. Last 12 months: over a limit 5 times (last February 2026). Source: EPA ECHO, Oct 22, 2026.

Reports due
About 28 days after each period: outfall 001 form A monthly (40 values), outfall 101 form A1 monthly (5 values), outfall 102 form A monthly (2 values), outfall TRAD form E monthly (7 values)
Last report on file
August 2026
Oct 2024 – Sep 2025
8 values over a limit, 0 required values missing, 0 of 48 reports late

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

Period endingParameterReportedLimitOver by
February 2026Phosphorus, total [as P], maximum monthly average.256 mg/L≤ .18 mg/L42%
February 2026Phosphorus, total [as P], maximum weekly average.485 mg/L≤ .27 mg/L80%
February 2026Phosphorus, total [as P], maximum weekly average60.91 lb/d≤ 45 lb/d35%
February 2026Solids, total suspended, maximum weekly average46.157 mg/L≤ 34 mg/L36%
February 2026Solids, total suspended, maximum weekly average5976.49 lb/d≤ 5600 lb/d7%

Limits in force (62)

ParameterStatisticLimitMonthsOutfall
Oxygen, dissolved [DO]minimum weekly average≥ 6 mg/LFeb–May001
Oxygen, dissolved [DO]monthly average minimum≥ 5.5 mg/LJan, Jun, Jul, Aug, Sep, Oct, Nov, Dec001
Oxygen, dissolved [DO]instantaneous minimum≥ 5 mg/Lall year001
BOD, 5-day, 20 deg. Cmaximum monthly average≤ 23 mg/Lall year001
BOD, 5-day, 20 deg. Cmaximum weekly average≤ 34 mg/Lall year001
BOD, 5-day, 20 deg. Cmaximum monthly average≤ 3800 lb/dall year001
BOD, 5-day, 20 deg. Cmaximum weekly average≤ 5600 lb/dall year001
pHminimum≥ 6.3 SUall year001
pHmaximum≤ 8.5 SUall year001
Solids, total suspendedmaximum monthly average≤ 23 mg/Lall year001
Solids, total suspendedmaximum weekly average≤ 34 mg/Lall year001
Solids, total suspendedmaximum monthly average≤ 3800 lb/dall year001
Solids, total suspendedmonthly totalreport only (lb/mo)all year001
Solids, total suspendedmaximum weekly average≤ 5600 lb/dall year001
Solids, total suspendedannual maximum≤ 1400286 lb/yrall year001
Nitrogen, total [as N]monthly totalreport only (lb/mo)all year001
Nitrogen, total [as N]annual maximum≤ 243645 lb/yrall year001
Nitrogen, total [as N]annual totalreport only (lb/yr)Dec001
Nitrogen, total [as N]monthly averagereport only (mg/L)all year001
Nitrogen, organic total [as N]monthly averagereport only (mg/L)all year001
Nitrogen, ammonia total [as N]monthly average≤ 6.9 mg/LMay–Oct001
Nitrogen, ammonia total [as N]monthly averagereport only (mg/L)Jan, Feb, Mar, Apr, Nov, Dec001
Nitrogen, ammonia total [as N]maximum daily average≤ 11 mg/LMay–Oct001
Nitrogen, ammonia total [as N]daily maximumreport only (mg/L)Jan, Feb, Mar, Apr, Nov, Dec001
Nitrogen, ammonia total [as N]maximum monthly average≤ 1150 lb/dMay–Oct001
Nitrogen, ammonia total [as N]monthly averagereport only (lb/d)Jan, Feb, Mar, Apr, Nov, Dec001
Nitrogen, ammonia total [as N]maximum weekly average≤ 1835 lb/dMay–Oct001
Nitrogen, ammonia total [as N]daily maximumreport only (lb/d)Jan, Feb, Mar, Apr, Nov, Dec001
Nitrogen, Kjeldahl, total [as N]monthly averagereport only (mg/L)all year001
Nitrite + Nitrate total [as N]monthly averagereport only (mg/L)all year001
Phosphorus, total [as P]maximum monthly average≤ .18 mg/Lall year001
Phosphorus, total [as P]maximum weekly average≤ .27 mg/Lall year001
Phosphorus, total [as P]maximum monthly average≤ 30 lb/dall year001
Phosphorus, total [as P]monthly totalreport only (lb/mo)all year001
Phosphorus, total [as P]maximum weekly average≤ 45 lb/dall year001
Phosphorus, total [as P]annual totalreport only (lb/yr)Dec001
Phosphorus, total [as P]annual maximum≤ 10964 lb/yrall year001
Flow, in conduit or thru treatment plantmonthly averagereport only (MGD)all year001
Flow, in conduit or thru treatment plantmonthly maximumreport only (MGD)all year001
Chlorine, total residualdaily maximum≤ .1 mg/Lall year001
Enterococcimaximum≤ 35 MPN/100mLall year001
Phosphorous, in total orthophosphatemonthly averagereport only (mg/L)all year001
Bromide [as Br]valuereport only (mg/L)Mar, Jun, Sep, Dec001
Polychlorinated biphenyls [PCB] pg/Lquarterly totalreport only (g/g)Mar, Jun, Sep, Dec001
Polychlorinated biphenyls [PCB] pg/Lannual totalreport only (g/yr)Dec001
BOD, 5-day, percent removalminimum≥ 85 %all year001
Solids, suspended percent removalminimum≥ 85 %all year001
Flow, totalmonthly totalreport only (Mgal/mo)all year001
Turbidityvaluereport only (NTU)all year101
Chlorine, total residualmaximumreport only (mg/L)all year101
Flowmonthly averagereport only (MGD)all year101
Flowdaily maximumreport only (MGD)all year101
Flow, totalmonthly totalreport only (Mgal/mo)all year101
BOD, 5-day, 20 deg. Cmonthly averagereport only (mg/L)all year102
Solids, total suspendedmonthly averagereport only (mg/L)all year102
Solids, total suspendedcumulative totalreport only (lb/yr)all yearTRAD
Solids, total suspendedcumulative totalreport only (lb/yr)all yearTRAD
Nitrogen, total [as N]cumulative totalreport only (lb/yr)all yearTRAD
Nitrogen, total [as N]cumulative totalreport only (lb/yr)all yearTRAD
Phosphorus, total [as P]cumulative totalreport only (lb/yr)all yearTRAD
Phosphorus, total [as P]cumulative totalreport only (lb/yr)all yearTRAD
Flowyear-to-date totalreport only (Mgal/yr)all yearTRAD

How strict are these limits?

Cited limits by parameter: Maryland'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/MD0021865 · MCP: https://passage-data.com/mcp