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Boston Harbor and Massachusetts Bay
MWRA Environmental Quality Department

The Neponset River

Boston Harbor Page Harbor Beaches Page Charles River Page Mystic River Page Neponset River Page
Boston Harbor Beaches Charles River Mystic River Neponset River


The Neponset River often fails to meet state bacterial water quality standards, except at the river mouth, where river water mixes with cleaner harbor water. Water quality does not consistently meet standards near Tenean Beach or the Commercial Point combined sewer overflow treatment facility outfall.

MWRA's Environmental Quality Department manages water quality data on bacteria, algae, water clarity, dissolved oxygen, nutrients, and suspended solids in Boston Harbor and its tributary rivers.

Neponset River  sampling map
See larger map with sampling locations

See all Harbor & river sampling locations

Water Quality Parameter

Historic Range for the Neponset*


Dissolved Oxygen

3.79 -  11.97 mg/L   Mean: 7.82

Download physical data

(1554 readings)


44.9 -  81.1 deg F   Mean: 64.4
(1552 readings)


0.12 -  32.71 PSU   Mean: 27.36
(1507 readings)


6.68 -  8.09   Mean: 7.76
(1463 readings)

secchi disk2.jpg

Secchi Disk Depth

0.3 -  2.7 m   Mean: 1.29

Download clarity data

(683 readings)
TSS 0.57 -  69.6 mg/L   Mean: 10.37
(190 readings)


Nutrient Chemistry

PO4: 0.05 -  1.5 umol/L   Mean: 0.66

Download nutrients data

(165 readings)

Chlorophyll & Phaeophytin

Chl a: 0.74 -  41.7 umol/l   Mean: 5.55
(164 readings)



0 -  27800 count/100 mL  Geo. mean: 5

Download bacteria data

(961 readings)

E. coli

52 -  3130 count/100 mL  Geo. mean: 178
(61 readings)

Fecal coliform

0 -  2340000 count/100 mL  Geo. mean: 22
(982 readings)


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