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Clean Water Act discharge permit · NPDES MA0103284

MWRA DEER ISLAND TREATMENT PLANT, Boston, MA: NPDES MA0103284 discharge permit, effluent exceedances, inspections, penalties

MWRA DEER ISLAND TREATMENT PLANT, held by MWRA - DEER ISLAND P O T W, holds NPDES permit MA0103284, which discharges to Atlantic Ocean (Boston Harbor). EPA’s file records it issued May 20, 1999 and expiring July 31, 2005. The status and dates are as EPA’s permit file stood when Velarion loaded it (September 15, 2026); EPA’s free Detailed Facility Report on ECHO carries the permit’s current standing.

Identity

Facility as filedMWRA DEER ISLAND TREATMENT PLANT
Permittee as filedMWRA - DEER ISLAND P O T W
NPDES IDMA0103284
Permit statusAdministratively continued (past its expiration date and still in force until reissued)
Permit typeIndividual permit
Discharger classMajor discharger
Facility typePublicly owned treatment works
ProgramPublicly owned treatment works
IssuedMay 20, 1999
Expiration dateJuly 31, 2005
AddressBoston, MA 02152
Receiving waterATLANTIC OCEAN (BOSTON HARBOR)
Receiving water impaired303(D) Listed
SubwatershedMystic River-Frontal Boston Harbor (HUC 010900010502)

Cited to the EPA ICIS-NPDES permit file (ECHO download).

Effluent limits and exceedances

An effluent exceedance is a discharge monitoring report value over the permit’s numeric limit (EPA’s violation code E90). A violation of any kind also counts a report not filed. Each row is EPA’s own count for that pollutant.

Pollutant or measureLimitsViolations, any kindEffluent exceedancesLatest exceedanceLargest exceedance, as filed
LC50 Static 48Hr Acute Menidia954June 30, 202599,999% over the limit
Coliform, fecal general3962April 30, 200411% over the limit
Solids, total suspended4242August 31, 200244% over the limit
NOEL Static 1Hr 20min Fert. Chronic Arbacia punctulata322September 30, 200599,999% over the limit
Chlorine, total residual3041December 31, 200043% over the limit
pH3031December 31, 2000
LC50 Static 48Hr Acute Americamysis bahia (formerly Mysidopsis bahia)921December 31, 202596% over the limit
Noael Statre 7Day Chronic Menidia321July 31, 200699,999% over the limit
Flow, total611October 31, 200523% over the limit
Flow, in conduit or thru treatment plant14350
LC50 Static 48Hr Acute D. Pulex660
LC50 Pass/Fail Static 24Hr Acute Ceriodaphnia450
LC50 Pass/Fail Static 24Hr Acute Pimephales promelas450
BOD, 5-day, 20 deg. C2440
Duration of discharge840
LC50 Static 48Hr Acute Ceriodaphnia dubia640
CBOD5+NH3-N1830
Bypass valve1230
Rainfall2420
Copper, total recoverable620
Mercury, total [as Hg]620
LC50 Pass/Fail Static 24Hr Acute Americamysis bahia (formerly Mysidopsis bahia)410
LC50 Pass/Fail Static 24Hr Acute Menidia menidia410
Nitrogen, ammonia total [as N]310
Nitrogen, nitrite total [as N]310
Nitrogen, nitrate total [as N]310
Nitrogen, Kjeldahl, total [as N]310
Solids, settleable600
Arsenic, total [as As]600
PCB-1016600
4,4'-DDT600
Aldrin600
Chlordane, .alpha.-, whole water600
Chlordane [tech mix. and metabolites]600
Dieldrin600
Heptachlor600
Heptachlor epoxide600
PCB-1221600
PCB-1232600
PCB-1242600
PCB-1248600
PCB-1254600
PCB-1260600
Polychlorinated biphenyls [PCBs]600
Hexachlorobenzene600
.gamma.-Chlordane, whole water600
Cyanide, total recoverable600
Volatile fraction organics [EPA 624]600
Chloride [as Cl]300
Coliform, fecal - % samples exceeding limit300
Copper, total [as Cu]200

Cited to the EPA ICIS-NPDES limits and effluent violations files (ECHO download); up to 60 rows shown, most exceedances first.

Inspections, violations and enforcement

DateWhat EPA recordedAgency
July 21, 2026Wet-weather unanticipated prohibited bypass discharge to waters of the U.S. - endangermentEP6
July 21, 2026Wet-weather unanticipated prohibited bypass discharge to waters of the U.S. - endangermentEP6
July 7, 2026Wet-weather unanticipated prohibited bypass discharge to waters of the U.S. - endangermentEP6
March 16, 2026Wet-weather unanticipated prohibited bypass discharge to waters of the U.S. - endangermentEP6
March 16, 2026Wet-weather unanticipated prohibited bypass discharge to waters of the U.S. - endangermentEP6
June 30, 2025PR: Failure of the Control Authority to publish for SNC (Level II - Other)EP6

Velarion’s copy of EPA’s ICIS-NPDES files does not include the inspections, formal enforcement actions and informal enforcement actions files, so this page shows none of them. EPA’s free Detailed Facility Report on ECHO lists this permit’s inspections, enforcement actions and penalties.

Cited to the EPA ICIS-NPDES violation, inspection and enforcement files (ECHO download); up to 50 rows of each shown, newest first.

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How we handle your data → Privacy

EPA publishes a free Detailed Facility Report for every permit on ECHO: its compliance status quarter by quarter, its inspections, and its enforcement actions and penalties. EPA also sends free notices of new inspections and enforcement actions through ECHO Notify; enter NPDES ID MA0103284 there.

Nearby on the register

Figures from EPA’s ICIS-NPDES download, loaded September 15, 2026.