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National Park Service, Assateague Island National Seashore

Federal facility (Land, Mineral, Wildlife Conservation), Berlin, Maryland. NPDES permit MD0021091 expired Oct 31, 2024; its limits still apply. Last 12 months: over a limit 8 times (last May 2026), 10 required values missing, 2 of 12 reports late. Source: EPA ECHO, Oct 22, 2026.

Reports due
About 28 days after each period: form A monthly (34 values)
Last report on file
September 2026
Oct 2024 – Sep 2025
1 value over a limit, 0 required values missing, 0 of 12 reports late

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

Period endingParameterReportedLimitOver by
March 2026Solids, total suspended, maximum monthly average49.6 mg/L≤ 10 mg/L396%
March 2026Solids, total suspended, maximum weekly average1.63 lb/d≤ 1.5 lb/d9%
March 2026Solids, total suspended, maximum weekly average247.5 mg/L≤ 15 mg/L1550%
May 2026Phosphorus, total [as P], maximum monthly average1.62 mg/L≤ .3 mg/L440%
May 2026Phosphorus, total [as P], maximum weekly average.131 lb/d≤ .045 lb/d191%
May 2026Phosphorus, total [as P], maximum weekly average6.27 mg/L≤ .45 mg/L1293%
May 2026pH, maximum9 SU≤ 8.5 SU—
May 2026pH, minimum6.3 SU≥ 6.5 SU—

Limits in force (34)

ParameterStatisticLimitMonths
Oxygen, dissolved [DO]instantaneous minimum≥ 5 mg/Lall year
BOD, 5-day, 20 deg. Cmaximum monthly average≤ 10 mg/Lall year
BOD, 5-day, 20 deg. Cmaximum weekly average≤ 15 mg/Lall year
BOD, 5-day, 20 deg. Cmaximum monthly average≤ 1 lb/dall year
BOD, 5-day, 20 deg. Cmaximum weekly average≤ 1.5 lb/dall year
pHminimum≥ 6.5 SUall year
pHmaximum≤ 8.5 SUall year
Solids, total suspendedmaximum monthly average≤ 10 mg/Lall year
Solids, total suspendedmaximum weekly average≤ 15 mg/Lall year
Solids, total suspendedmaximum monthly average≤ 1 lb/dall year
Solids, total suspendedmaximum weekly average≤ 1.5 lb/dall year
Nitrogen, total [as N]maximum monthly average≤ 3 mg/Lall year
Nitrogen, total [as N]maximum weekly average≤ 4.5 mg/Lall year
Nitrogen, total [as N]maximum monthly average≤ .3 lb/dall year
Nitrogen, total [as N]maximum weekly average≤ .45 lb/dall year
Nitrogen, total [as N]monthly totalreport only (lb/mo)all year
Nitrogen, total [as N]annual maximum≤ 110 lb/yrall year
Nitrogen, total [as N]cumulative total≤ 55 lb/yrMay–Oct
Nitrogen, organic total [as N]monthly averagereport only (mg/L)all year
Nitrogen, ammonia 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]maximum monthly average≤ .3 mg/Lall year
Phosphorus, total [as P]maximum weekly average≤ .45 mg/Lall year
Phosphorus, total [as P]maximum monthly average≤ .03 lb/dall year
Phosphorus, total [as P]maximum weekly average≤ .045 lb/dall year
Phosphorus, total [as P]monthly totalreport only (lb/mo)all year
Phosphorus, total [as P]annual maximum≤ 11 lb/yrall year
Phosphorus, total [as P]cumulative total≤ 6 lb/yrMay–Oct
Phosphate, ortho [as P]monthly averagereport only (mg/L)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
Chlorine, total residualmaximum≤ .1 mg/Lall year
Coliform, fecal generalmonthly median≤ 14 MPN/100mLall year
Flow, totalmonthly totalreport only (Mgal/mo)all year

How strict are these limits?

Cited limits by parameter: Maryland'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/MD0021091 · MCP: https://passage-data.com/mcp